THE CLINICAL-DIAGNOSIS AND MISDIAGNOSIS OF SENILE DEMENTIA OF LEWY BODY TYPE (SDLT)

Background. Current clinical classifications do not contain specific d iagnostic categories for patients with senile dementia of the Lewy bod y type (SDLT), recently proposed as the second commonest neuropatholog ical cause of dementia in the elderly. This study determines how exist ing clinical diagnosis systems label SDLT patients and suggests how su ch patients may be identified. Method. A range of clinical diagnostic criteria for dementia were applied to case notes of autopsy-confirmed SDLT (n = 20), dementia of Alzheimer type (DAT; n = 21) and multi-infa rct dementia (MID; n = 9) patients who had received psychogeriatric as sessment. The predictive validity of each set of clinical criteria was calculated against the external criterion of neuropathological diagno sis. Results. Many SDLT patients erroneously met criteria for MID (35% with Hachinski scores greater than or equal to 7) or for DAT (15% by NINCDS 'probable AD', 35% by DSM-III-R DAT and 50% by NINCDS 'possible AD'). Up to 85% of SDLT cases could be correctly identified using rec ently published specific criteria. Conclusions. SDLT usually has a dis cernible clinical syndrome and existing clinical classifications may n eed revision to diagnose correctly such patients.