Summary

Hallucinations are one of the defining features of the clinical syndrome associated with cortical Lewy body pathology. However, it is not clear whether the time course of hallucinations in Lewy body dementia is different from that in other dementias. We therefore studied the natural history of hallucinations in dementia. Since neuroleptics may be used to treat hallucinations and may have deleterious effects, we also examined the impact of neuroleptic use on cognitive decline. Ninety-eight patients with dementia were assessed every 4 months on a median of eight occasions. Fifty-one patients came to autopsy. Our longitudinal study shows that hallucinations beginning within the first three years of dementia are associated with cortical Lewy body pathology and reduced life expectancy. Patients with cortical Lewy body pathology were more likely to have persistent as opposed to fleeting hallucinations. This information could be incorporated into operational clinical criteria for Lewy body dementia. We did not find an increased mortality amongst those with cortical Lewy body pathology who took neuroleptics. However, men who took neuroleptics had a more rapid rate of cognitive decline than those who did not. This association was not apparent in women. We did not find evidence of increased fluctuation in cognitive ability in the Lewy body group.

Introduction

The appearance of hallucinations in the context of dementia has implications for diagnosis, prognosis and management. The possibility that hallucinations occur as part of a clinical syndrome is suggested by the findings that hallucinations co-occur more commonly than would be expected with fluctuating cognitive impairment (Ballard et al., 1993) and with extrapyramidal symptoms in patients having a clinical diagnosis of Alzheimer's disease (Mayeux et al., 1985).