Showing posts with label dendritic spine. Show all posts
Showing posts with label dendritic spine. Show all posts

Friday, 1 June 2018

Autism, Power Outages and the Starving Brain?

There are certain Critical Periods in the development of the human brain and these are the most vulnerable times to any genetic or environmental insult.  Critical Periods (CPs) will be the subject of post appearing shortly.

Another power outage waiting to happen

 Have you wondered why autism secondary to mitochondrial disease (regressive autism) almost always seem to occur before five years of age, and usually much earlier?  Why does it not happen later? Why is it's onset often preceded by a viral infection?
I think you can consider much of this in terms of the brain running out of energy. Humans have evolved to require a huge amount of energy to power their developing brains, a massive 40% of the body’s energy is required by the brain in early childhood.  If your overload a power grid it will end in a blackout.
We know many people with autism have a tendency towards mitochondrial dysfunction, they lack some key enzyme complexes. This means that the process of OXPHOS (Oxidative phosphorylation), by which the body converts glucose to usable energy (ATP), is partially disabled. 

We saw in earlier posts how the supply of glucose and oxygen to the brain can be impaired in autism because there is unstable blood flow.

It is just like in your house, all your electrical appliances might mean you need a 25KW supply, because you do not use them all at the same time. Just to be on the safe side you might have a 40KW limit. What if the power company will only give you a 20 KW connection? If you turn on the clothes drier, the oven, the air conditioning and some other things all of a sudden you blow the main fuse and perhaps damage the hard drive of your old computer.
So, in the power-hungry brain of a three-year-old, you add a viral infection and all of a sudden you exceed the available power supply from the mitochondria, that have soldered on for 3years with impaired supply of complex 1 and imperfect cerebral blood flow. By the sixth year of life, the peak power requirement from the brain would have fallen to within the safe limit of the mitochondria and its impaired supply of complex 1.  Instead of blowing the fuse, which is easy to reset, you have blown some neuronal circuitry, which is not so easy to repair.    

Too Many Synapses?
We know that it is the synapses in the brain that are the big energy users and we also know that in most autism there are too many synapses. So, in that group of autism there is an even bigger potential energy demand.

Note that in Alzheimer’s type dementia (AD in the above chart) you see a severe loss of synapses/spines as atrophy takes place. This occurs at the same time as a loss of insulin sensitivity occurs (type 3 diabetes). Perhaps the AD brain is also starved of energy, it does seem to respond to ketosis (ketones replacing glucose as the fuel) and it responds to Agmatine (increasing blood flow via eNOS).
We also know that adolescent synaptic pruning is dysfunctional in autism and we even know why. Interestingly by modifying GABAA function with bumetanide we may indeed allow the brain to eliminate more synapses (a good thing), so possibly an unexpected benefit from Ben Ari’s original idea.

"Working with a mouse model we have shown that, at puberty, there is an increase in inhibitory GABA receptors, which are targets for brain chemicals that quiet down nerve cells. We now report that these GABA receptors trigger synaptic pruning at puberty in the mouse hippocampus, a brain area involved in learning and memory." The report, published by eLife, "Synaptic pruning in the female hippocampus is triggered at puberty by extrasynaptic GABAA receptors on dendritic spines."            
These findings may suggest new treatments targeting GABA receptors for "normalizing" synaptic pruning in diseases such as autism and schizophrenia, where synaptic pruning is abnormal. Research has suggested that children with autism may have an over-abundance of synapses in some parts of the brain.

Synaptic pruning in the female hippocampus is triggered at puberty by extrasynaptic GABAA receptors on dendritic spines

Adolescent synaptic pruning is thought to enable optimal cognition because it is disrupted in certain neuropathologies, yet the initiator of this process is unknown. One factor not yet considered is the α4βδ GABAA receptor (GABAR), an extrasynaptic inhibitory receptor which first emerges on dendritic spines at puberty in female mice. Here we show that α4βδ GABARs trigger adolescent pruning. Spine density of CA1 hippocampal pyramidal cells decreased by half post-pubertally in female wild-type but not α4 KO mice. This effect was associated with decreased expression of kalirin-7 (Kal7), a spine protein which controls actin cytoskeleton remodeling. Kal7 decreased at puberty as a result of reduced NMDAR activation due to α4βδ-mediated inhibition. In the absence of this inhibition, Kal7 expression was unchanged at puberty. In the unpruned condition, spatial re-learning was impaired. These data suggest that pubertal pruning requires α4βδ GABARs. In their absence, pruning is prevented and cognition is not optimal.

Strange Patterns of Growth
Longitudinal studies are when researchers collect the same data over long period of years. Most autism research is just based on a single snapshot in time.
One observation of mine is that some people with strictly defined autism (SDA) are born at the 90+ percentile for height, but then fall back to something like the 20 percentile. Body growth has dramatically slowed. Was this because energy has been diverted to the overgrowing brain? 
A five-year old’s brain is an energy monster. It uses twice as much glucose (the energy that fuels the brain) as that of a full-grown adult, a new study led by Northwestern University anthropologists has found.
It was previously believed that the brain’s resource burden on the body was largest at birth, when the size of the brain relative to the body is greatest. The researchers found instead that the brain maxes out its glucose use at age 5. At age 4 the brain consumes glucose at a rate comparable to 66 percent of the body’s resting metabolic rate (or more than 40 percent of the body’s total energy expenditure). 

“The mid-childhood peak in brain costs has to do with the fact that synapses, connections in the brain, max out at this age, when we learn so many of the things we need to know to be successful humans,” Kuzawa said.

“At its peak in childhood, the brain burns through two-thirds of the calories the entire body uses at rest, much more than other primate species,” said William Leonard, co-author of the study. “To compensate for these heavy energy demands of our big brains, children grow more slowly and are less physically active during this age range. Our findings strongly suggest that humans evolved to grow slowly during this time in order to free up fuel for our expensive, busy childhood brains.” 

Full paper: -

The high energetic costs of human brain development have been hypothesized to explain distinctive human traits, including exceptionally slow and protracted preadult growth. Although widely assumed to constrain life-history evolution, the metabolic requirements of the growing human brain are unknown. We combined previously collected PET and MRI data to calculate the human brain’s glucose use from birth to adulthood, which we compare with body growth rate. We evaluate the strength of brain–body metabolic trade-offs using the ratios of brain glucose uptake to the body’s resting metabolic rate (RMR) and daily energy requirements (DER) expressed in glucose-gram equivalents (glucosermr% and glucoseder%). We find that glucosermr% and glucoseder% do not peak at birth (52.5% and 59.8% of RMR, or 35.4% and 38.7% of DER, for males and females, respectively), when relative brain size is largest, but rather in childhood (66.3% and 65.0% of RMR and 43.3% and 43.8% of DER). Body-weight growth (dw/dt) and both glucosermr% and glucoseder% are strongly, inversely related: soon after birth, increases in brain glucose demand are accompanied by proportionate decreases in dw/dt. Ages of peak brain glucose demand and lowest dw/dt co-occur and subsequent developmental declines in brain metabolism are matched by proportionate increases in dw/dt until puberty. The finding that human brain glucose demands peak during childhood, and evidence that brain metabolism and body growth rate covary inversely across development, support the hypothesis that the high costs of human brain development require compensatory slowing of body growth rate. 

To quantify the metabolic costs of the human brain, in this study we used a unique, previously collected age series of PET measures of brain glucose uptake spanning birth to adulthood (32), along with existing MRI volumetric data (36), to calculate the brain’s total glucose use from birth to adulthood, which we compare with body growth rate. We estimate total brain glucose uptake by age (inclusive of all oxidative and nonoxidative functions), which we compare with two measures of whole-body energy expenditure: RMR, reflecting maintenance functions only, and daily energy requirements (DER), reflecting the combination of maintenance, activity, and growth. We hypothesized that ages of peak substrate competition (i.e., competition for glucose) between brain and body would be aligned developmentally with the age of slowest childhood body growth, and more generally that growth rate and brain glucose use would covary inversely during development, as is predicted by the concept of a trade-off between brain metabolism and body growth in human life-history evolution. 

Daily glucose use by the brain peaks at 5.2 y of age at 167.0 g/d and 146.1 g/d in males and females, respectively. These values represent 1.88- and 1.82-times the daily glucose use of the brain in adulthood (Fig. 1 A and B and SI Appendix, Fig. S2), despite the fact that body size is more than three-times as large in the adult.

Glucose use of the human brain by age. (A) Grams per day in males. (B) Grams per day in females; dashed horizontal line is adult value (A and B). (C) Glucosermr% (solid line) and glucoseder% (dashed line) in males. (D) Glucosermr% (solid line) and glucoseder% (dashed line) in females.

The most relevant data is the line highlighted in yellow below, showing brain consumption of glucose peaks at 40% (of total body consumption) around 5 years old and drops to 20% in adulthood.

Our findings agree with past estimates indicating that the brain dominates the body’s metabolism during early life (31). However, our PET-based calculations reveal that the magnitude of brain glucose uptake, both in absolute terms and relative to the body’s metabolic budget, does not peak at birth but rather in childhood, when the glucose used by the brain comprises the equivalent of 66% of the body’s RMR, and roughly 43% of total expenditure. These findings are in broad agreement with past clinical work showing that the body’s mass-specific glucose production rates are highest in childhood, and tightly linked with the brain’s metabolic needs (40). Whereas past attempts to quantify the contribution of the brain to the body’s metabolic expenditure suggested that the brain accounted for a continuously decreasing fraction of RMR as the brain-to-body weight ratio declined with age (25, 31), we find a more complex pattern of substrate trade-off. Both glucosermr% and glucoseder% decline in the first half-year as a fast but decelerating pace of body growth established in utero initially outpaces postnatal increases in brain metabolism. Beginning around 6 mo, increases in relative glucose use are matched by proportionate decreases in weight growth, whereas ages of declining brain glucose uptake in late childhood and early adolescence are accompanied by proportionate increases in weight growth. The relationships that we document between age changes in brain glucose demands and body-weight growth rate are particularly striking in males, who maintain these inverse linear trends despite experiencing threefold changes in brain glucose demand and body growth rate between 6 mo and 13 y of age. In females, an earlier onset of pubertal weight gain leads to earlier deviations from similar linear inverse relationships.

What the researchers then did was to see how the growth rate of the brain is correlated to the growth rate of the body. In effect that what they found was that the growth of the body has to slow down to allow the energy hungry brain to develop.  One the brain has passed its peak energy requirement at about 5 years old, body growth can then gradually accelerate. 
The brain is the red line, the body is blue. The chart on the left is males and the one on the right is females. 
So, we might suspect that in 2 to 4-year olds who seem not to be growing as fast as we might expect, the reason is that their brain is over-growing, a key feature of classic autism.

Glucoseder% and body-weight growth rate. Glucoseder% and weight velocities plotted as SD scores to allow unitless comparison. (A) Glucoseder% (red dots) and dw/dt (blue dots) by age in males. (B) Glucoseder% (red dots) and dw/dt (blue dots) by age in females

Brain Overgrowth in Autism
As has been previous commented on in this blog, Eric Courchesne has pretty much figured out what goes wrong in the growth trajectory of the autistic brain; that was almost 15 years ago.

Brain development in autism: early overgrowth followed by premature arrest of growth.

Author information


Due to the relatively late age of clinical diagnosis of autism, the early brain pathology of children with autism has remained largely unstudied. The increased use of retrospective measures such as head circumference, along with a surge of MRI studies of toddlers with autism, have opened a whole new area of research and discovery. Recent studies have now shown that abnormal brain overgrowth occurs during the first 2 years of life in children with autism. By 2-4 years of age, the most deviant overgrowth is in cerebral, cerebellar, and limbic structures that underlie higher-order cognitive, social, emotional, and language functions. Excessive growth is followed by abnormally slow or arrested growth. Deviant brain growth in autism occurs at the very time when the formation of cerebral circuitry is at its most exuberant and vulnerable stage, and it may signal disruption of this process of circuit formation. The resulting aberrant connectivity and dysfunction may lead to the development of autistic behaviors. To discover the causes, neural substrates, early-warning signs and effective treatments of autism, future research should focus on elucidating the neurobiological defects that underlie brain growth abnormalities in autism that appear during these critical first years of life.

Research from 2017: -

A record of children’s height and weight and even head circumference is usually collected by their doctor. In an earlier post I did ask why they bother if nobody is checking this data. If a child falls from the 90th percentile in height to the 20th, something clearly is going on.
When I discussed this with a pediatric endocrinologist a few years ago, we then measured bone-age and IGF-1. If you have low IGF-1 and retarded bone age you might opt for some kind of growth hormone therapy.
In what is broadly defined as autism, I think we have some distinctly different things possibly happening: -

Group AMD
Energy conversion in the brain is less efficient than it should be due to a combination of impaired vascular function and impaired mitochondrial enzyme complex production. No symptoms are apparent and developmental milestones are achieved.  As the brain creates more synapses it energy requirement grows until the day when the body has some external insult like a viral infection, and the required power is not available, triggering a “power outage” which appears as the regression into autism. In biological terms there has been death of neurons and demyelination.

Group Sliding Down the Percentiles 
This group looks like a sub-set of classic autism. The brain grows too rapidly in the first two years after birth and this causes the expected slowing of body growth to occur much earlier than in typical children. This manifests itself in the child tumbling down the percentiles for height and weight.
The brain then stops growing prematurely, reducing energy consumption and allowing body growth to accelerate and the child slowly rises back up the height/weight percentiles.

Perhaps all those excessive synapses that were not pruned correctly are wasting glucose and so delay the growth of the rest of the body?   
In the sliding down the growth percentiles group, does this overgrowing brain ever exceed maximum available power? Maybe it just grows too fast and so mal-develops, as suggested by Courchesne, or maybe it grows too fast and cannot fuel correct development?  What happens if you increase maximum available power in this group, in the way some athletes use to enhance their performance/cheat?
All I know for sure is that in Monty, aged 14 with autism, increasing eNOS (endothelial nitric oxide synthase) using agmatine seems to make him achieve much more, with the same daily glucose consumption. I wonder what would happen if Agmatine was given to very young children as soon as it was noted that they were tumbling down the height percentiles?  This is perhaps what the pediatric endocrinologists should be thinking about, rather than just whether or not to administer growth hormones/IGF-1.
If you could identify Group AMD before the “power outage” you might be able to boost maximum power production or reduce body growth slightly and hence avoid the brain ever being starved of energy. That way you would not have most regressive autism.

Thursday, 27 July 2017

Targeting Dendritic Spines to Improve Cognitive Function and Behavior in Autism; plus Hair Loss/Graying

I have written several posts about dendritic spines and their varying shapes (morphology).  This sounds like a rather obscure subject, but it looks like it may be a key area where both behavior and cognition can be modified, even later in life.

Homer Simson after using a Wnt Activator 

Dendritic spines

In a typical neuron (brain cell) you have dendrites at one end and so-called axon terminals at the other. When neurons connect with each other, an axon terminal connects with a dendritic spine from another close by neuron.  Axons transmit electrochemical signals from one neuron to the dendrites of other neurons.  The junction formed between a dendritic spine and an axon terminal is called a synapse.

One neuron can have as many as 15,000 spines, some of which are picking up signals from axon terminals of other neurons.
The number and shape of these spines is constantly changing and not surprisingly defects in this process affect both cognition and behavior.
The other end of the neuron, with the axon terminals is much less studied.  The myelin sheath deserves a mention. This protective coating is constantly being repaired in a process called remyelination. MS (Multiple Sclerosis) is caused by damage to the myelin coating that does not self repair. A newly identified feature of autism is an abnormally thin layer of myelin. A lack of insulation along the axon will affect the flow of electrical signals.
Many factors are involved in dendritic spine morphology and plasticity. Many of the same factors are known to be disturbed in autism and other related dysfunctions (schizophrenia, bipolar, ADHD etc).
Recall that within autism there are two broad groups; the larger group has “too many” dendritic spines and the smaller group has “too few”. I am writing about the larger group. My post is a simplification of a complex subject.
Factors that influence dendritic spine morphology and plasticity include:- 

·        BDNF  (want less)

·        Estrogen  (want more)

·        Reelin (want more)

·        BCL2 (want more)

·        PAK1 (want less)

·        GSK3 beta (want more)

·        PTEN (want more)

All the above seem to work via

·        Wnt signaling (want less) 

BDNF is a growth factor within the brain, which tends to be elevated in most autism.
The female hormone estrogen seems to be reduced in male autism and this will have many effects via something called ROR alpha. There is also reduced expression of estrogen receptor beta.
Reelin is a protein that is critical in brain development and maintenance. Reelin is implicated in most brain diseases, including autism. It stimulates dendritic spine development. Reelin is found to be reduced in autism.
BCl2 is a very well-known cancer gene/protein. BCL2 is part of a broader family of genes/proteins that control cell growth/death. BCL2 is anti-apoptotic, meaning it encourages growth rather than cell death. You will find elevated BCL2 in cancers.  BCL2 is implicated in both schizophrenia and autism.
Bax is another key member of the BCL2 family. The BCL2 protein duels with Bax, its counteracting twin. When Bax is in excess, cells execute a death command. When BCL2 dominates, the program is inhibited and cells survive. In cancer you want more Bax.
Modulating BCL2/Bax has been proposed as an autism therapy in Japan.
BCL2 is found to be reduced in autism.
The Japanese proposed the use of Navitoclax, a drug responsible for inhibiting BCL2 production for the treatment of cancer. I think they want to activate BCL2 production. 
I covered PAK1 in some lengthy posts. This was what the Japanese Nobel Laureate at MIT was working on. In summary, a PAK1 inhibitor should be helpful in autism, schizophrenia and some cancer.  Some people with a condition called neurofibromatosis, where non-cancerous tumors grow, use a special kind of bee propolis that contains a substance called CAPE (caffeic acid phenethyl ester), that is a mild PAK1 inhibitor.

GSK3 beta plays a role in several key signaling pathways. Abnormal expression of GSK3 beta is associated with Bipolar disorder. One role played by GSK3 beta is in Wnt signaling, which then affects dendritic spines. A GSK3 beta inhibitor, like lithium, is a Wnt activator which will increase the number of dendritic spines.
PTEN is a tumor suppressor gene/protein that is also an autism gene.
PTEN deficiency results in abnormal arborization and myelination in humans. PTEN-deficient neurons in brains of animal models have increased synaptic spine density.
People with autism and PTEN mutations have large heads because they lacked enough PTEN to reign in cell growth (and head growth).  You would expect them to have increased synaptic spine density.
Note than in both autism/cancer genes (BCL2 and PTEN) the balance is shifted towards growth, which fits in with the broad concept of autism as a growth dysfunction.
Wnt signaling is a complex and only partially understood subject, that has been previously discussed in this blog.  The short version is that most people with autism and particularly the ones with large heads will likely have too much Wnt signaling as the result of their various metabolic “disturbances”. The best way to inhibit their Wnt signaling might be to counter their particular metabolic disturbances, so if you are one of the 2% of autism with a PTEN mutation, then increase your PTEN levels.  If this is not possible than any other way to inhibit Wnt might be effective.
In Bipolar, where GSK3 beta is a known risk gene, you want more dendritic spines and so you want a GSK3 beta inhibitor like lithium. 
I think lithium will have a negative effect on most autism. Within children diagnosed with autism, a minority may well better fit a diagnosis of bipolar.


Children with autism spectrum disorder (ASD) have higher rates of comorbid psychiatric disorders, including mood disorders, than the general child population. Although children with ASD may experience irritability (aggression, self-injury, and tantrums), a portion also experience symptoms that are typical of a mood disorder, such as euphoria/elevated mood, mania, hypersexuality, paranoia, or decreased need for sleep. Despite lithium's established efficacy in controlling mood disorder symptoms in the neurotypical population, lithium has been rarely studied in children with ASD.


We performed a retrospective chart review of 30 children and adolescents diagnosed with ASD by the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text Revision (DSM-IV-TR) criteria who were prescribed lithium in order to assess target symptoms, safety, and tolerability. Clinical Global Impressions - Improvement (CGI-I) ratings were performed by two board-certified child psychiatrists with expertise in ASD. CGI-I scores were dichotomized into "improved" (CGI-I score of 1 or 2) or "not improved" (CGI-I score ≥3).


Forty-three percent of patients who received lithium were rated as "improved" on the CGI-I. Seventy-one percent of patients who had two or more pretreatment mood disorder symptoms were rated as "improved." The presence of mania (p=0.033) or euphoria/elevated mood (p=0.041) were the pretreatment symptoms significantly associated with an "improved" rating. The mean lithium blood level was 0.70 mEq/L (SD=0.26), and the average length of lithium treatment was 29.7 days (SD=23.9). Forty-seven percent of patients were reported to have at least one side effect, most commonly vomiting (13%), tremor (10%), fatigue (10%), irritability (7%), and enuresis (7%).


This preliminary assessment of lithium in children and adolescents with ASD suggests that lithium may be a medication of interest for those who exhibit two or more mood disorder symptoms, particularly mania or euphoria/elevated mood. A relatively high side effect rate merits caution, and these results are limited by the retrospective, uncontrolled study design. Future study of lithium in a prospective trial with treatment-sensitive outcome measures may be indicated.

Hair Growth and Graying 
One surprising observation is the apparent connection between dendritic spine modification and modifying growth/color of human hair.
The same pathway is involved in signaling growth and coloring in the hair on your head and growing the dendritic spines on the neurons inside your head. I have mentioned this once before in a previous post. It is relevant because if a substance is potent enough to affect your dendritic spines you would expect it also to have a visible effect on the hair, of at least some people.
For example one reader of this blog uses a PAK1 inhibitor to treat her case of autism and she found that it has a hair graying effect.

EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling

Pigmented hair regeneration requires epithelial stem cells (EpSCs) and melanocyte stem cells (McSCs) in the hair follicle.

Thus far, only a handful of signals that regulate McSCs have been identified, including extrinsic signals, such as transforming growth factor beta (TGFB) and Wnts, which are provided by the epithelial niche. Wnt signaling induces activation of EpSCs to drive epithelial regeneration while coordinately inducing McSCs to proliferate and differentiate to pigment regenerating hair follicle

One known but uncommon side effect of my current favourite Wnt inhibitor, Mebendazole, is hair loss. Hair follicles require Wnt signaling and if there is too little Wnt signaling you will lose some hair.
BCL2 is a very important cancer gene/protein but it also plays a role in autism and in dendritic spine morphology.  Low levels of the protein BCl2 leads to premature graying.

The team then looked at what would happen if they 'knocked out' a gene in mice that is known to be important for cell survival.
Mice lacking this Bcl2 gene went grey shortly after birth.

The scientists believe the same principle might apply in humans, which would explain why some people - such as TV presenter Philip Schofield - go grey in their 20s, while others keep their dark locks into retirement.

BCL2 is known to be reduced in the reduced in the brains of people with autism, as is another substance called Reelin.  Both Reelin and Bcl-2 are needed for dendritic spines to develop correctly.  

Autism is a severe neurodevelopmental disorder with potential genetic and environmental causes. Cerebellar pathology including Purkinje cell atrophy has been demonstrated previously. We hypothesized that cell migration and apoptotic mechanisms may account for observed Purkinje cell abnormalities. Reelin is an important secretory glycoprotein responsible for normal layering of the brain. Bcl-2 is a regulatory protein responsible for control of programmed cell death in the brain. Autistic and normal control cerebellar corteces matched for age, sex, and post-mortem interval (PMI) were prepared for SDS-gel electrophoresis and Western blotting using specific anti-Reelin and anti-Bcl-2 antibodies. Quantification of Reelin bands showed 43%, 44%, and 44% reductions in autistic cerebellum (mean optical density +/- SD per 30 microg protein 4.05 +/- 4.0, 1.98 +/- 2.0, 13.88 +/- 11.9 for 410 kDa, 330 kDa, and 180 kDa bands, respectively; N = 5) compared with controls (mean optical density +/- SD per 30 microg protein, 7.1 +/- 1.6, 3.5 +/- 1.0, 24.7 +/- 5.0; N = 8, p < 0.0402 for 180 kDa band). Quantification of Bcl-2 levels showed a 34% to 51% reduction in autistic cerebellum (M +/- SD per 75 microg protein 0.29 +/- 0.08; N = 5) compared with controls (M +/- SD per 75 microg protein 0.59 +/- 0.31; N = 8, p < 0.0451). Measurement of beta-actin (M +/- SD for controls 7.3 +/- 2.9; for autistics 6.77 +/- 0.66) in the same homogenates did not differ significantly between groups. These results demonstrate for the first time that dysregulation of Reelin and Bcl-2 may be responsible for some of the brain structural and behavioral abnormalities observed in autism.  


The development of distinct cellular layers and precise synaptic circuits is essential for the formation of well-functioning cortical structures in the mammalian brain. The extracellular protein Reelin through the activation of a core signaling pathway including the ApoER2 and VLDLR receptors and the adapter protein Dab1, controls the positioning of radially migrating principal neurons, promotes the extension of dendritic processes in immature forebrain neurons, and affects synaptic transmission. Here we report for the first time that the Reelin signaling pathway promotes the development of postsynaptic structures such as dendritic spines in hippocampal pyramidal neurons. Our data underscore the importance of Reelin as a factor that promotes the maturation of target neuronal populations and the development of excitatory circuits in the postnatal hippocampus. These findings may have implications for understanding the origin of cognitive disorders associated with Reelin deficiency.

While not everything relating to dendritic spines is variable, and hence potentially can be modified, much seems to be.
Rather like in this blog it took a few years to get a comprehensive view of the factors involved in neuronal chloride and extend the list of potential therapies, getting to the bottom of fine tuning dendritic spin morphology for improved behavior and cognition will be a complex task.
Much is already known.
Our reader AJ is busy looking at GSK3 beta inhibitors.
GSK3 beta is best known as a bipolar gene/protein, but it is becoming seen as an autism gene.

GSK3 is one of the few signaling mediators that play central roles in a diverse range of signaling pathways, including those activated by Wnts, hedgehog, growth factors, cytokines, and G protein-coupled ligands. Although the inhibition of GSK3-mediated β-catenin phosphorylation is known to be the key event in Wnt-β-catenin signaling, the mechanisms which underlie this event remain incompletely understood. The recent demonstration of GSK3 involvement in Wnt receptor phosphorylation illustrates the multifaceted roles that GSK3 plays in Wnt-β-catenin signaling. In this review, we will summarize these recent results and offer explanations, hypotheses, and models to reconcile some of these observations.
Recent advances indicate that GSK3 also plays a positive role in Wnt signal transduction by phosphorylating the Wnt receptors low density lipoprotein receptor-related protein (LRP5/6) and provide new mechanisms for the suppression of GSK3 activity by Wnt in β-catenin stabilization. Furthermore, GSK3 mediates crosstalk between signaling pathways and β-catenin-independent downstream signaling from Wnt.

it is known that glycogen synthase kinase 3β (GSK-3β) regulates both synaptic plasticity and memory. 
GSK-3β overexpression led to a general reduction in the number of dendritic spines. In addition, it caused a slight reduction in the percentage, head diameter and length of thin spines, whereas the head diameter of mushroom spines was increased.

Over the past 2 decades, neuroscientists have built a body of evidence that links not only bipolar disease, but other psychiatric disorders including autism and schizophrenia to abnormal brain development. In particular, they have found abnormalities in the numbers of synapses and in the shape of neurons at the points where they form synapses. Their studies have often implicated abnormal signaling in a brain pathway called Wnt, which is involved both in early brain development and later, more complex, refining of brain connections. The role of Wnt could help explain why lithium is effective: It blocks an enzyme called GSK-3 β, which is an inhibitor on the Wnt pathway. By boosting Wnt signaling, lithium could produce a therapeutic effect in psychiatric diseases in which the Wnt pathway is underpowered.

They then treated the mutant mice with lithium. Although the researchers acknowledge that rodents are an imperfect proxy for human mood disorders, they did observe that the animals’ symptoms markedly improved; studies of their brains also revealed normal numbers of spines. “That’s the key finding,” Cheyette says. “It suggests that lithium could have its well-known therapeutic effect on patients with bipolar disorder by changing the stability of spines in the brain.”

GSK3 has numerous effects.

Glycogen synthase kinase-3 (GSK-3) is a cytoplasmic serine/threonine protein kinase that phosphorylates and inhibits glycogen synthase, thereby inhibiting glycogen synthesis from glucose. However, this serine/threonine kinase is now known to regulate numerous cellular processes through a number of signaling pathways important for cell proliferation, stem cell renewal, apoptosis and development. Because of these diverse roles, malfunction of this kinase is also known to be involved in the pathogenesis of human diseases, such as nervous system disorders, diabetes, bone formation, inflammation, cancer and heart failure. Therefore, GSK-3 is recognized as an attractive target for the development of new drugs. The present review summarizes the roles of GSK-3 in the insulin, Wnt/β-catenin and hedgehog signaling pathways including the regulation of their activities. The roles of GSK-3 in the development of human diseases within the context of its participation in various signaling pathways are also summarized. Finally, the possibility of new drug development targeting this kinase is discussed with recent information about inhibitors and activators of GSK-3.  


The present study demonstrates that estradiol may trigger formation of new dendritic spines by activation of a cAMPregulated CREB phosphorylation. Induction of the CREB response requires activation of NMDA receptors, increased intracellularcalciumconcentrationsandcAMP-activatedPKA.These systems together then contribute to the CREB response, which in turn leads to the morphological changes seen with estradiol—i.e., spine formation. The biochemical and cellular routes leading from activated CREB to the morphological change in dendritic spine density are still uncharted.

Dendritic spines of the medial amygdala: plasticity, density, shape, and subcellular modulation by sex steroids.

The medial nucleus of the amygdala (MeA) is a complex component of the "extended amygdala" in rats. Its posterodorsal subnucleus (MePD) has a remarkable expression of gonadal hormone receptors, is sexually dimorphic or affected by sex steroids, and modulates various social behaviors. Dendritic spines show remarkable changes relevant for synaptic strength and plasticity. Adult males have more spines than females, the density of dendritic spines changes in the course of hours to a few days and is lower in proestrous and estrous phases of the ovarian cycle, or is affected by both sex steroid withdrawal and hormonal replacement therapy in the MePD. Males also have more thin spines than mushroom-like or stubby/wide ones. The presence of dendritic fillopodia and axonal protrusions in the MePD neuropil of adult animals reinforces the evidence for local plasticity. Estrogen affects synaptic and cellular growth and neuroprotection in the MeA by regulating the activity of the cyclic AMP response element-binding protein (CREB)-related gene products, brain-derived neurotrophic factor (BDNF), the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and the activity-regulated cytoskeleton-related protein (Arc). These effects on signal transduction cascades can also lead to local protein synthesis and/or rearrangement of the cytoskeleton and subsequent numerical/morphological alterations in dendritic spines. Various working hypotheses are raised from these experimental data and reveal the MePD as a relevant region to study the effects of sex steroids in the rat brain.


CNS deletion of Pten in the mouse has revealed its roles in controlling cell size and number, thus providing compelling etiology for macrocephaly and Lhermitte-Duclos disease. PTEN mutations in individuals with autism spectrum disorders (ASD) have also been reported, although a causal link between PTEN and ASD remains unclear. In the present study, we deleted Pten in limited differentiated neuronal populations in the cerebral cortex and hippocampus of mice. Resulting mutant mice showed abnormal social interaction and exaggerated responses to sensory stimuli. We observed macrocephaly and neuronal hypertrophy, including hypertrophic and ectopic dendrites and axonal tracts with increased synapses. This abnormal morphology was associated with activation of the Akt/mTor/S6k pathway and inactivation of Gsk3β. Thus, our data suggest that abnormal activation of the PI3K/AKT pathway in specific neuronal populations can underlie macrocephaly and behavioral abnormalities reminiscent of certain features of human ASD.  

Mutations in phosphatase and tensin homolog deleted on chromosome ten (PTEN) are implicated in neuropsychiatric disorders including autism. Previous studies report that PTEN knockdown in neurons in vivo leads to increased spine density and synaptic activity. To better characterize synaptic changes in neurons lacking PTEN, we examined the effects of shRNA knockdown of PTEN in basolateral amygdala neurons on synaptic spine density and morphology using fluorescent dye confocal imaging. Contrary to previous studies in dentate gyrus, we find that knockdown of PTEN in basolateral amygdala leads to a significant decrease in total spine density in distal dendrites. Curiously, this decreased spine density is associated with increased miniature excitatory post-synaptic current frequency and amplitude, suggesting an increase in number and function of mature spines. These seemingly contradictory findings were reconciled by spine morphology analysis demonstrating increased mushroom spine density and size with correspondingly decreased thin protrusion density at more distal segments. The same analysis of PTEN conditional deletion in dentate gyrus demonstrated that loss of PTEN does not significantly alter total density of dendritic protrusions in the dentate gyrus, but does decrease thin protrusion density and increases density of more mature mushroom spines. These findings suggest that, contrary to previous reports, PTEN knockdown may not induce de novo spinogenesis, but instead may increase synaptic activity by inducing morphological and functional maturation of spines. Furthermore, behavioral analysis of basolateral amygdala PTEN knockdown suggests that these changes limited only to the basolateral amygdala complex may not be sufficient to induce increased anxiety-related behaviors. 

Aberrant regulation of WNT/β-catenin signaling has a crucial role in the onset and progression of cancers, where the effects are not always predictable depending on tumor context. In melanoma, for example, models of the disease predict differing effects of the WNT/β-catenin pathway on metastatic progression. Understanding the processes that underpin the highly context-dependent nature of WNT/β-catenin signaling in tumors is essential to achieve maximal therapeutic benefit from WNT inhibitory compounds. In this study, we have found that expression of the tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alters the invasive potential of melanoma cells in response to WNT/β-catenin signaling, correlating with differing metabolic profiles. This alters the bioenergetic potential and mitochondrial activity of melanoma cells, triggered through regulation of pro-survival autophagy. Thus, WNT/β-catenin signaling is a regulator of catabolic processes in cancer cells, which varies depending on the metabolic requirements of tumors.

A meta-analysis of blood BDNF in 887 patients with ASD and 901 control subjects demonstrated significantly higher BDNF levels in ASD compared to controls with the SMD of 0.47 (95% CI 0.07-0.86, p = 0.02). In addition subgroup meta-analyses were performed based on the BDNF specimen. The present meta-analysis study led to conclusion that BDNF might play role in autism initiation/ propagation and therefore it can be considered as a possible biomarker of ASD.

Dendritic spines are major sites of excitatory synaptic transmission and changes in their numbers and morphology have been associated with neurodevelopmental and neurodegenerative disorders. Brain-derived Neurotrophic Factor (BDNF) is a secreted growth factor that influences hippocampal, striatal and neocortical pyramidal neuron dendritic spine density. However, the mechanisms by which BDNF regulates dendritic spines and how BDNF interacts with other regulators of spines remain unclear. We propose that one mechanism by which BDNF promotes dendritic spine formation is through an interaction with Wnt signaling. Here, we show that Wnt signaling inhibition in cultured cortical neurons disrupts dendritic spine development, reduces dendritic arbor size and complexity, and blocks BDNF-induced dendritic spine formation and maturation. Additionally, we show that BDNF regulates expression of Wnt2, and that Wnt2 is sufficient to promote cortical dendrite growth and dendritic spine formation. Together, these data suggest that BDNF and Wnt signaling cooperatively regulate dendritic spine formation.

Other Wnt inhibitors

Yet another anti-parasite drug, Niclosamide,  turns out to be a Wnt inhibitor. 

Not surprisingly, Niclosamide is now a candidate drug to treat several different types of cancer.  It is also thought to have great potential in suppressing the metastatic process of prostate cancer. Another extremely cheap drug, not available in the US.
Even the flavonoid quercetin can inhibit Wnt. 

Therapeutic Avenues

There certainly are many potential ways to fine tune dendritic spine morphology.
Some readers of this blog are already doing just that, perhaps not all realizing it. 
·        BDNF  (want less - TrkB inhibitor)

·        Estrogen 

·        Reelin (want more – statin via RAS activation)

·        BCL2 (want more – statin)

·        PAK1 (want less – PAK inhibitor, BIO30)

·        GSK3 beta (want more – GSK3 activator)

·        PTEN (want more – statin)

All the above seem to work via

·        Wnt signaling (want less – Mebendazole/Niclosamide etc)

If you inhibit GSK3 beta you activate Wnt. You need get things the right way around. 
Statins promote RAS signaling which appears to increase Reelin expression. 


Fine tuning dendritic spine morphology seems like a good target for those with MR/ID and also those with any kind of neurological disorder.
There appear to be many ways to achieve this.
It seems a plausible idea and in many ways seems more credible than the idea of a diuretic (bumetanide) raising some people’s IQ.
The big issue is which substances have sufficient potency, once they have crossed the blood brain barrier, to do anything at all.  This is an issue with all therapies targeting the brain, including bumetanide.
At least substances that can affect hair growth and color are making it through to the bloodstream, which is a start.
Does this mean that tuning your dendritic spines will inevitably make your hair turn grey or begin to thin?  I don’t think so. I think this will happen in people who have low to normal Wnt signaling to start with.
Do some people with naturally premature graying, or thinning, hair have low levels of Wnt signaling? Quite possibly. Are they more likely to have traits of bipolar/creativity? Look for actors with gray or thinning hair.
Do people with autism tend to have full heads of thicker hair, as well as bigger heads?
Do the minority of people with autism and small heads have thinning hair?
Some readers of this blog are already using statins to treat autism. As has been pointed out in earlier posts, other than lowing cholesterol, statins have potent anti-inflammatory effects and they also affect expression of RAS, PTEN and BCL2, all of which are implicated in autism and all affect dendritic spines. It seems plausible that these readers are already modifying dendritic spine morphology.