Severe agitation—restlessness, wandering, or screaming—may accompany late-life psychosis or dementia, with particularly high prevalence rates in nursing homes. Aggression and assaultiveness may also occur as a consequence of the delusions or hallucinations of late-life psychosis from dementia, depression, or a combination of these factors. Behavioral and psychiatric symptoms develop in as many as 60% of community-dwelling dementia patients (Lyketsos et al. 2000; Ryu et al. 2005; Tractenberg et al. 2003; Wragg and Jeste 1988). The lifetime risk of behavioral complications of dementia approaches 100% (Lyketsos et al. 2000). Rates of physical aggression range from 11% to 46% among community-dwelling dementia patients and from 31% to 42% among patients in institutional settings (Billig et al. 1991; Brodaty et al. 2003; Cohen-Mansfield et al. 1995; Peabody et al. 1987; Wragg and Jeste 1988; Zimmer et al. 1984). The etiology of agitation and aggression in late-life psychosis or dementia is unknown, although environmental and biological factors, such as drug toxicity, medical illness, pain, frustration, loneliness, reduced sensory input, new surroundings, diminished nutritional status, and altered central nervous system (CNS) function, alone or in combination, may play important roles (Mintzer and Brawman-Mintzer 1996).