Synaptic Density and Autism, explained

….or at a podcast with at least an attempt at an explanation of what synaptic density is and how it is affected in brains of people with autism. This week we review three convergent lines of evidence – whole brain, brain cell then genes within those brain cells – that show that the autistic brain has a decrease in cell-to-cell communication in multiple brain regions, leading to social communication impairments.

https://www.science.org/doi/pdf/10.1126/science.adh2602?casa_token=bjtbuFi5U88AAAAA:_ffcE-pGCPxh4re24ix_xDgenAS1cAgDHLIMJJQCCG_1LvxaJKrGwEb9LFuMNsTYhvtGqRwro1A1Smc

https://academic.oup.com/cercor/article-abstract/34/13/121/7661138?redirectedFrom=fulltext&login=false#no-access-message

https://pubmed.ncbi.nlm.nih.gov/39367053

More about the environmental influences in autism

New research points to a previously understudied but fascinating mechanism by which environmental factors may lead to autism: it’s called the “GABA/glutamate switch” which is a critical period in development when certain cells turn from turning on cell activity to turning them off. These environmental factors may delay this process leading to long term effects on the developing brain consistent with autism. While this data on the mechanism is brand new, the topic of the environment in autism was inspired by a recent effort at NIEHS which is developing an interactive database for people to access information about what environmental exposures have been studied and how in autism.

https://www.niehs.nih.gov/news/events/aware

https://www.pnas.org/doi/epub/10.1073/pnas.2406928121

Research for the end of Autism Action Month

In honor of the last week of Autism Awareness/Acceptance Month, we review two new scientific findings that call for more awareness and action, and less acceptance of the status quo. First: sex differences in autism are not well understood, and as it turns out, the influences on a diagnosis are different. Males have a higher rate of heritability compared to females. Second, those with rare genetic disorders have very few options for treatment, but a new study promises hope for more personalized approaches. The researchers use Timothy Syndrome as an example of how cells can start to function properly through a targeted approach which focuses on a small part of a gene. This is potentially life saving for individuals with this disorder.

https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/38630491/

https://www.nature.com/articles/s41586-024-07310-6

Little Brains Answer Big Questions

This week we talk to Sergiu Pasca from Stanford University. He has revolutionized the field of understanding the field of brain development in neurodevelopmental disorders and just published a new study which examined the genetic influence of brain assembly. The way he does this is quite remarkable. His lab uses assembloids, which are many many many stem cells which form into a tiny brain. He explains what an interneuron is, why it is important for brain function, and how genetics can influence how these neurons work. This way the development of the brain from the first cell can be tracked and even manipulated to understand what happens in autism, and what therapies might be the most helpful to target these interneurons. Thank you Dr. Pasca.

Open access! https://pubmed.ncbi.nlm.nih.gov/37758944/

Top reasons to study the autistic brain

There are dozens of good reasons why scientists need to study the brains of people with autism. One is to understand what happens in the brain as people with autism get older and see how the brain changes over time. Another is to identify mechanisms of autism to help all neuroscientists figure out how the brain works. A third is improve medicine by determining what helps what people at what age. Scientists @UCDavis, @Penn and @UCLA examined the individual brain cells of people with autism to address these three questions, revealing that the autistic brain shows some similarities to brains of people with Alzheimer’s Disease. In addition, inflammation seen in the brain may be caused by too much activity of cells talking to each other. Studying the brains of people with autism is essential to better understanding and is made possible by families who are committed to research. www.autismbrainnet.org.

https://pubmed.ncbi.nlm.nih.gov/36862688/

The molecular signature of the autism brain

Is there a specific “signature’ that make the autism brain unique? Can there be a common set of findings that certain gene expression goes up and another go down and where? And is it linked to behavior? This week, Dr. Michael Gandal at University of Pennsylvania (formerly UCLA) explains his recent findings that looks at the largest number of brain tissue samples so far from multiple brain regions to show a common up regulation of immune genes in the brain and a common down regulation of genes which control synapse formation and neuronal communication. It is most pronounced in areas involved in sensory processing of the brain. You can listen to the podcast today and read the whole paper here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9668748/pdf/41586_2022_Article_5377.pdf

Environmental factors as both causes and interventions?

Environmental exposures, including toxic chemicals, can contribute to the causes of ASD. But how do other environmental factors, like behavioral supports, work in the brain to improve behaviors associated with ASD? For this, you need a broad interpretation of the term “environmental” and an animal model so you can see the mechanism involved. Studies show while environmental factors can contribute, they can also provide modifications in cellular and molecular function which support learning and improved developmental trajectory. Finally, on a different topic, are autistic adults more likely to be involved in a crime compared to other groups? No, they are not, but there are factors which affect the risk of being involved with the criminal justice system, at least in the UK. Read more in the studies below.

https://pubmed.ncbi.nlm.nih.gov/34972219/

https://pubmed.ncbi.nlm.nih.gov/35259351/

https://pubmed.ncbi.nlm.nih.gov/35261275/

What the h**l is an induced pluripotent stem cell?

The words “induced pluripotent stem cell” refer to a group of cells that are gathered from a person with a disorder, like autism, then changed or “induced” from a skin cell into an embryonic “stem” cell, and can be then made into baby brain cells, or baby heart cells or baby bone cells. This makes them “pluripotent”. This tool has been used in neurodevelopment disorders to help illustrate when the wiring of the brain starts to go off course. Things start to happen very early after conception and one of the only ways to study these things is by using either embryonic cells or these induced embryonic “stem cells”. The latter is more cost effective and more precise. This technology has an incredibly high potential in understanding autism, but it may never be used as a treatment. Nevertheless, knowing how and when brain development deviates is essential for understanding people with ASD.

https://link.springer.com/content/pdf/10.1007%2F978-3-030-45493-7.pdf

The latest on marijuana and autism across the globe

Since the ASF policy statement on marijuana for the treatment of ASD was published this summer, there have been some new scientific studies that may be of interest to families.  As it turns out CBD has opposite effects in the brains of people with autism compared to those without autism, meaning that it is absolutely essential that more research is done specifically in people across the spectrum in ASD.  Also, early studies in Israel and Brazil are showing some positive effects on behavior, but they are open label non controlled compassionate use basis studies, which in encouraging, but the science needs to be more rigorous and more studies need to be done in people with autism using standardized autism assessments if any progress is to be made.  Luckily a new study at NYU is enrolling for just that approach.  Please contact Latoya.King@nyulangone.edu if you want to learn more about that.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6732821/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6784992/

https://www.ncbi.nlm.nih.gov/pubmed/31736860

https://www.ncbi.nlm.nih.gov/pubmed/30382443

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336869/