Baron-Cohen has conducted extensive studies [1,2] examining the prevalence of autism spectrum conditions (ASCs) and mathematical or scientific ability. Most of these studies, however, have focused mostly on (Cambridge) undergraduates or winners of the UK Mathematics Olympiad.
In one study, Baron-Cohen found in [2] that Olympiad winners scored the highest in the AQ test ($\mathrm{AQ}\colon 24.5,\mathrm{ SD}\colon 5.7$), with the second highest scoring group being the mathematics students ($\mathrm{AQ}\colon 21.5,\mathrm{ SD}\colon 6.4$).$^1$ This leads one to conjecture that autistic traits may be more prominent among individuals with higher mathematical ability.
Question: What is the population evidence$^2$ around autism/autistic traits in mathematics? If possible, at the postgraduate level in professional mathematicians?
Disclaimer: There is a another question focused on the postgraduate maths skill set: Is there any evidence for the distinction between undergrad and postgrad mathematics?.
$^1$Note however that the sample is small: $n=16$ for UK Olympiad winners, $n=85$ for mathematics students.
$^2$As in measuring the average AQ of mathematicians against other groups, such as graduate students, undergraduates, and controls.
References
[1] Baron-Cohen, Simon, Sally Wheelwright, Amy Burtenshaw, and Esther Hobson. "Mathematical talent is linked to autism." Human nature 18, no. 2 (2007): 125-131.
[2] Baron-Cohen, Simon, Sally Wheelwright, Richard Skinner, Joanne Martin, and Emma Clubley. "The autism-spectrum quotient (AQ): Evidence from Asperger syndrome/high-functioning autism, males and females, scientists and mathematicians." Journal of autism and developmental disorders 31, no. 1 (2001): 5-17.