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

Bladder and bowel incontinence frequently appears in the late stages of dementia, ^[1,2] probably due to loss of prefrontal control over the voiding reflexes. ^[1,3] Loss of sphincter control is considered to be a hallmark of moderate or severe dementia and is an item included in many functional assessment tools. ^[4,5] However, the relationship between cognitive decline and incontinence is not simple, ^[6] and little is known about their temporal pattern of evolution in different types of dementing illnesses.

Urinary incontinence is a marker of early vascular dementia, ^[7] and it is a secondary item in the two recent proposals of criteria for the clinical diagnosis of vascular dementia, ^[8,9] and in the clinical criteria of ``Binswanger's disease.'' ^[10] However, early incontinence could be also present in Alzheimer's disease (AD) with associated vascular lesions or in other dementing illnesses and could mislead in the identification of vascular dementia.

Urinary incontinence is a conspicuous and troublesome event ^[11] and may represent a general marker for the staging of dementia. It could be used as an end point in clinical and therapeutic longitudinal studies, provided it was determined that the development of incontinence relates to cognitive decline in a well-defined way.

We addressed these issues in a series of demented patients from a longitudinal prospective study followed until their death, whose onset of bladder incontinence was clearly specified in clinical records and in whom we obtained a definite pathologic diagnosis. We studied the time of urinary incontinence in several types of dementias and the relationship between cognitive performance and loss of bladder control. We anticipated that cognitive decline and incontinence would have different patterns of evolution in separate dementing illnesses.

Methods.