Anatomy and aging of the amygdala and hippocampus in autism spectrum disorder: an in vivo magnetic resonance imaging study of Asperger syndrome.
Adults with Asperger syndrome carry a persistently larger amygdala and no age-linked growth—expect heightened emotion and watch for later memory decline.
01Research in Context
What this study did
Griffith et al. (2012) scanned adults with Asperger syndrome and matched controls. They measured the size of two brain areas: the amygdala and the hippocampus.
The team wanted to know if these areas age differently in Asperger adults compared with typical adults.
What they found
Adults with Asperger syndrome had larger amygdalae than controls.
The Asperger group also lacked the normal age-related amygdala growth seen in controls. Hippocampal size was the same in both groups.
How this fits with other research
Gandhi et al. (2022) followed autistic adults for 2–3 years and saw faster hippocampal shrinkage and memory decline. Griffith et al. (2012) only took one-time pictures, so they missed this later loss.
Lange et al. (2015) tracked ASD brains from childhood to adulthood. They found early over-growth, then decline. Griffith et al. (2012) captured the adult endpoint, showing the amygdala stays large while other areas start to shrink.
Mason et al. (2021) found that larger amygdala size in autistic children strengthens the link between anxiety and fear responses. Griffith et al. (2012) give us the structural reason: the amygdala is already enlarged in Asperger adults.
Why it matters
When you see strong emotional reactions or anxiety in adults with Asperger syndrome, remember their amygdala is larger and does not grow with age. This stable size may keep emotional circuits on high alert. Pair your behavior plans with anxiety tools and monitor for memory changes as clients reach middle age.
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02At a glance
03Original abstract
It has been proposed that people with autism spectrum disorder (ASD) have abnormal morphometry and development of the amygdala and hippocampus (AH). However, previous reports are inconsistent, perhaps because they included people of different ASD diagnoses, ages, and health. We compared, using magnetic resonance imaging, the in vivo anatomy of the AH in 32 healthy individuals with Asperger syndrome (12-47 years) and 32 healthy controls who did not differ significantly in age or IQ. We measured bulk (gray + white matter) volume of the AH using manual tracing (MEASURE). We first compared the volume of AH between individuals with Asperger syndrome and controls and then investigated age-related differences. We compared differences in anatomy before, and after, correcting for whole brain size. There was no significant between group differences in whole brain volume. However, individuals with Asperger syndrome had a significantly larger raw bulk volume of total (P<0.01), right (P<0.01), and left amygdala (P<0.05); and when corrected for overall brain size, total (P<0.05), and right amygdala (P<0.01). There was a significant group difference in aging of left amygdala; controls, but not individuals with Asperger syndrome, had a significant age-related increase in volume (r = 0.486, P<0.01, and r = 0.007, P = 0.97, z = 1.995). There were no significant group differences in volume or age-related effects in hippocampus. Individuals with Asperger syndrome have significant differences from controls in bulk volume and aging of the amygdala.
Autism research : official journal of the International Society for Autism Research, 2012 · doi:10.1002/aur.227