Excessive blood vessel growth

When we think of autism we tend to focus on the differences in our brains as compared to neurotypicals. A favourite fact of mine about the autistic brain is that while no two brains are alike, neurotypical brains are all quite similar, whereas autistic brains show a lot of variation not only in relation to neurotypical brains, but other autistic brains as well. You can read about that here:

Autistic brain differences pt. 1 – Connectivity

As it turns out research is now showing that we are unique in other body systems too, like our blood vessels.

Blood vessel growth

Both autistic mice* and human autopsies of autistic people show a greater amount of blood vessel growth—called angiogenesis—compared to neurotypicals.^[1]Persistent Angiogenesis in the Autism Brain: An Immunocytochemical Study of Postmortem Cortex, Brainstem and Cerebellum

In the images below, you can see that while the density of blood vessels decreases slightly in autistic subjects as they get older, it remains fairly consistent; whereas in neurotypicals the blood vessel growth was only seen at a young age.^[2]Persistent Angiogenesis in the Autism Brain: An Immunocytochemical Study of Postmortem Cortex, Brainstem and Cerebellum

Julie Ouellette, a graduate student working in Lacoste Lab (run by Dr. Baptiste Lacoste) at the University of Ottawa, said:

We can’t just look at neurons; the vessels are developing
and growing with the neurons in parallel, so it would make
sense that both of them are closely related.^[3]Study links changes in blood flow to autism | Spectrum

• These mice underwent an autism-linked deletion in chromosome 16 (a deletion of 16p11.2 to be exact), resulting in a mutation that produces autism-like behavior in mice, including hyperactivity and excessive/obsessive grooming.^[4]Study links changes in blood flow to autism | Spectrum

Blood flow

Brain imaging studies also show differences in blood flow between autistics and non-autistics, which are linked to neural activity.^[5]Study links changes in blood flow to autism | Spectrum

Autistic mice show a better distribution of blood flow. When their little whiskers are tickled with an electric toothbrush, their neurons (brain cells) are activated, and their blood flow shows differences compared with non-autistic mice. Julie Ouellette states:

The vascular response to neural activity is not normal.^[6]Study links changes in blood flow to autism | Spectrum

Researchers noted an irregularity in blood flow that was not due to a change in blood pressure, nor a change in heart rate.

Other changes of the blood vessels in autistics include that drugs that make blood vessels contract or relax do not have any effect on some major brain blood vessels, in particular the middle cerebral artery.^[7]Study links changes in blood flow to autism | Spectrum

Blood vessel cells

The blood vessel cells themselves—the so-called endothelium—are constructed uniquely. One could say that they are asocial, as they do not form branches that connect with other blood vessel cells.

On a personal note, I think it is pretty cool that the cells don’t respond the same way nor reach out to connect with each other. I also wonder if the reason for the greater blood flow is due to many of us being autodidacts, and needing extra nutrients and oxygen to support the way our fantastic brains work.

This yet unpublished research was presented on November 7, 2018, at the
2018 Society for Neuroscience annual meeting in San Diego, California.