Temporal pattern of cognitive decline and incontinence is different in Alzheimer's disease and diffuse Lewy body disease

Incontinence is a hallmark of dementia, but little is known about its inception in different types of dementing disease. We recorded the dates of onset of dementia and of urinary incontinence in 73 demented patients followed for 5.6 +/- 2.5 years. The pathologic diagnosis was Alzheimer's disease (AD) in 29 cases, diffuse Lewy body disease (DLBD) in 11 cases, AD with Lewy bodies (AD+LB) in 13 cases, and AD with vascular lesions (AD+VL) in 20 cases. The onset of urinary incontinence was significantly earlier in DLBD cases (3.2 +/- 1.4 years after dementia onset) than in AD (5.9 +/- 2.5), AD+LB (5.8 +/- 2.4), and AD+VL (6.5 +/- 2.3) (p < 0.01). At the onset of bladder incontinence, the mean score in the Extended Dementia Scale was significantly higher (i.e., cognition was better) in DLBD cases (109.3 +/- 70.8) than in AD (21.3 +/- 40.4), AD+LB (45.6 +/- 45.1), and AD+VL (39.2 +/- 54.9) cases (p < 0.01). Urinary incontinence is associated with severe cognitive decline in pure AD but usually precedes severe mental failure in DLBD cases. This temporal pattern of cognitive decline and incontinence could be useful in differentiating these two dementing illnesses.