Some years ago, I received an email from Jane Pickett, director of brain resources and data for what was then the Autism Tissue Program (now Autism BrainNet). Jane was excited: She had collected a brain weighing well over 1,700 grams — notably larger than that of the average adult.
“It could shed light on the nature of macrocephaly in autism,” she said. Macrocephaly, or a large head, sometimes accompanies autism. Although I hated to disappoint her, I explained that the increased size was likely due to a postmortem artifact: After death, the molecular pump that maintains the cell’s balance of electrolytes shuts down. In this state, inappropriate handling of the brain allows water to diffuse freely into cells, causing the brain to swell. The observed macrocephaly, which was not apparent during this person’s life, was therefore not a likely consequence of autism, but a change that affected the tissue after death.
These sorts of artifacts are pervasive in postmortem brain samples. Brain weight, for example, can be affected by many variables, including the individual’s cause of death, the duration of a terminal illness and the method of tissue fixation1.
The rest of the blog can be read: bit.ly/analyze_caution