We studied an 84-year-old man with a 20-year history of nocturnal viol
ent behavior during sleep, but no other clinically evident neuropsychi
atric disorders. Polysomnographic investigations confirmed that he suf
fered from REM sleep behavior disorder (RED). Histopathologic examinat
ion revealed that he had Lewy body disease with a marked decrease of p
igmented neurons in the locus ceruleus and substantia nigra. These his
tologic findings represent the first documented evidence of a loss of
brainstem monoaminergic neurons in clinically idiopathic RED and sugge
st that Lewy body disease might provide an explanation for idiopathic
RED in the aged.