Deficiency of hexosaminidase A causes the GM2 gangliosidosis known as
Tay-Sachs disease. It is now known that this condition has several late-
onset variants that cause numerous neuropsychiatric disturbances. Early
recognition is important because treatment with phenothiazines and
heterocyclic antidepressants may worsen the course. The authors report two
cases with several new findings, including prominent psychiatric symptoms
without psychosis early in the course of the illness.