MOTOR AND COGNITIVE FUNCTION IN LEWY BODY DEMENTIA - COMPARISON WITH ALZHEIMERS AND PARKINSONS DISEASES

Objective-Motor and cognitive function were compared in patients with Lewy body dementia, Parkinson's disease, or Alzheimer's disease, to id entify features that may be clinically useful in differentiating Lewy body dementia from Alzheimer's disease and Parkinson's disease. Method s-A range of neuropsychological function and extrapyrimidal signs (EPS ) was assessed in 16 patients with Lewy body dementia, 15 with Parkins on's disease, 25 with Alzheimer's disease, and 22 control subjects. Re sults-The severity of total motor disability scores increased in the f ollowing order: controls approximate to Alzheimer's disease much less than Parkinson's disease < Lewy body dem:entia. Compared with patients with Parkinson's disease, patients with Lewy body dementia had greate r scores for rigidity and deficits in the finger tapping test, but res t tremor and left/right asymmetry in EPS were more evident in Parkinso n's disease. Patients with Lewy body dementia were also less likely to present with left/right asymmetry in EPS at the onset of their parkin sonism. ''Sensitivity'' to neuroleptic drugs was noted in 33% of patie nts with Lewy body dementia. Alzheimer's disease and Lewy body dementi a groups had greater severity of dementia compared with the Parkinson' s disease group and controls. Neuropsychological evaluation disclosed severe but similar degrees of impaired performances in tests of attent ion (digit span), frontal lobe function (verbal fluency, category, and Nelson card sort test) and motor sequencing in both Lewy body dementi a and Alzheimer's disease groups, than Parkinson's disease and control s. In the clock face test, improved performance was noted in the ''cop y'' compared to ''draw'' part of the test in controls, patients with A lzheimer's disease, and those with Parkinson's disease, bur: not in th e patients with Lewy body dementia, who achieved equally poor scores i n both parts of the test. Conclusions-EPS in Lewy body dementia resemb le those seen in idiopathic Parkinson's disease, although less rest tr emor and left/right asymmetry but more severe rigidity favours a diagn osis of Lewy body dementia. The unique profile of patients with Lewy b ody dementia seen in the clock face test suggests that this simple and easy to adminster test may be useful in the clinical setting to diffe rentiate Lewy body dementia and Alzheimer's disease.