Summary

A clinical diagnosis of dementia of Lewy body type (DLT) was made in 10% of referrals to a clinical service providing psychogeriatric care to a locality based population of 18,000 people aged >65 years. Thirty per cent of referrals received a diagnosis of Alzheimer's disease and 22% of multi-infarct dementia. Inter-rater agreement for the three different diagnoses was equally good (kappa = 0.67) and the profile of differential diagnosis was stable in two consecutively sampled years. We suggest that a cluster of symptoms exists which we can reliably define in clinical practice as dementia of Lewy body type. It may be useful to view a person with any three of the following features, cognitive impairment, extrapyramidal symptoms, fluctuating confusion and visual hallucinations, as most likely having DLT, regardless of coexisting cerebrovascular disease or other physical illnesses, both to avoid potentially hazardous treatments such as conventional neuroleptics and to select patients for future beneficial interventions.

Introduction

Does Lewy body dementia* exist in clinical practice? Can it be recognized in the routine work of an old age psychiatry service? In whom do we recognize Lewy body dementia, and what character does it have? Our own interest in these questions began in the late 1980s when we were looking at cases of presumed Charles Bonnet syndrome. At the same time, colleagues in Newcastle were describing senile dementia of Lewy body type. We soon found the second diagnosis subsumed the first. In this chapter, we report on our subsequent experiences with the diagnosis of Lewy body dementia and attempt to answer our questions from the perspective of the sole service for elderly people with mental health problems within a geographically limited area.