Autism is a complex disease with a diverse phenotype and it is often described as a spectrum disorder due to this behavioral heterogeneity. While autism’s etiology is still unknown, some patients with the disease display excessive early growth of the brain. This paper investigates the secreted amyloid precursor protein-alpha (sAPPα), a protein also involved in Alzheimer’s disease, and finds a link between elevated levels of the protein and severe autism. The authors postulate that sAPPα leads to overgrowth in the brain of autistic patients by contributing to the anabolic environment. Other brain disorders such as schizophrenia and Alzheimer’s are associated with decreases in brain volume. How much overlap in the biochemical pathways and biomarkers is there in the literature (or would you expect) for these diverse cognitive disorders?