Alterations in CACNA1C are associated with impaired working memory and function of the dorsolateral prefrontal cortex (dlPFC),1,2 and increased risk of schizophrenia, bipolar disorder, posttraumatic stress disorder, and Alzheimer disease (AD).1,2,3,4,5,6,7 All of these disorders are worsened by stress exposure8,9 and involve dysfunction of the recently evolved dlPFC, which subserves working memory, top-down control, and abstract reasoning.10 However, it is not known why this specific calcium channel is so important to dlPFC functioning. This evidence concerns the gene CACNA1C and Alzheimer disease.