Behavioral disturbances are a prevalent and important aspect of dementia of the Alzheimer type, but they have been relatively neglected by researchers. To characterize patients as having dementia, at least two goals should be addressed: first, determining a reliable definition and categorical diagnosis of dementia using such criteria as the Diagnostic and Statistical Manual of Mental Disorders (DSM)–IV and the International Classification of Diseases (ICD)–10; second, establishing a reliable and valid measurement of the severity of cognitive and noncognitive impairment by means of rating scales. DSM-IV and ICD-10 do not provide definitions of behavioral disturbance, whereas more than 100 geriatric rating scales exist that include some measurement of behavioral disturbances of dementia. There is a need for consensus on the term for these noncognitive symptoms. Some authors prefer the subdivisions of (a) psychiatric and noncognitive symptomatology into psychiatric symptoms, or syndromes and behavioral distrubances; and (b) cognitive syndromes. Given the frequency and clinical significance of behavioral and psychiatric disturbances in dementia, a standardized assessment procedure is needed for reliably and comprehensively describing psychiatric phenomena and behavioral disturbances in patients with dementia.