Sundowning syndrome in demented patients without neuroleptic therapy.

Characterisation of sundowning syndrome, defined as 'an exacerbation of symptoms indicating increased arousal or impairment in late afternoon, evening or at night, among elderly demented individuals', is complicated by neuroleptic therapy and frequent failure to specify the nature of the associated dementia. Screening by a memory disorders unit of an institutionalized population of 30 neuroleptic-free demented patients revealed 8 sundowners, with diagnoses of probable Alzheimer's disease (n = 5), frontal lobe dementia (n = 1), Lewy body disease (n = 1), and sequelae of herpes encephalitis (n = 1). Sundowners did not differ from non-sundowners in age, Mini Mental State score, degree of temporal and spatial disorientation or perceptual delusion. Sundowning was related to restlessness (P < 0.0001), sleep disorder (P < 0.003) and a history of hypotension lipothymia (P < 0.08). These results provide further evidence for a chronobiological explanation of sundowning syndrome.