Classification of psychotic symptoms in dementia sufferers.

Little attention has been payed to the classification of psychotic symptoms in dementia sufferers. This article compares the etiology of delusions, visual hallucinations and delusional misidentification and examines the value of factors generated from principal components analysis as a possible classificatory system in a group of 125 patients with DSM-III-R dementia in contact with clinical services who were prospectively evaluated using standardized instruments to describe in detail individual psychotic symptoms. The assessment also included the Geriatric Mental State Schedule, the History and Aetiology Schedule and the CAMCOG. Delusions and visual hallucinations had a distinct cognitive profile as did delusions and delusional misidentification, although there was an overlap between visual hallucinations and delusional misidentification. Four factors were generated from principal components analysis. Three of these closely mirrored the 3 symptom groups delusions, visual hallucinations and delusional misidentification, although the phantom-boarder delusion was correlated with the visual hallucination factor and not delusional misidentification. The fourth factor included visual hallucinations of relatives and delusions that relatives were in the house. This factor was strongly inversely associated with emotional distress and could perhaps best be seen as a comfort phenomena. The pattern of cognitive deficits and etiological associations of each of the factors were independent of one another, supporting the notion that it is useful to consider them as separate entities.