This review provides a comprehensive overview of currently available treatments for psychogeriatric disorders, summarizing the efficacy of various treatment approaches based on research evidence. The severe mental illnesses in geriatric age-groups can be classified into the following groups: delirium, dementia, depression, mania, psychotic disorders, and anxiety disorders. There are specific disorders requiring specific treatments within each group. Effective treatments exist for most disorders. Effective treatment for delirium consists of identifying and treating an underlying cause, and the judicious use of medications for specific symptoms. Treatment for the dementias involves two considerations: (1) treatment of the cognitive symptoms; and (2) treatment of the behavioral symptoms. There are no currently FDA-approved, or generally acknowledged as effective, medications for the cognitive symptoms. Some medications marketed for other purposes may be used by some clinicians for treating cognitive symptoms. One medication, tacrine, is available under a treatment IND for patients with Alzheimer's disease (AD). Behavioral symptoms such as agitation, hallucinations, and delusions occur in a majority of patients some time during their illness. The treatment of behavioral symptoms involves behavioral management, environmental manipulations, and the use of medication for control of specific syndromes. The few medications assessed in randomized trials include neuroleptics and benzodiazepines. Neuroleptics such as haloperidol or thioridazine are modestly effective for some symptoms and are probably the treatments of choice for the acute, short-term. Benzodiazepines may be somewhat less effective, have cognitive-impairing side effects, are associated with increased falls, and, therefore, are less preferred. Many other medications have been suggested based largely on clinical experience. They include carbamazepine, trazodone, buspirone, and others. Treatment for depression involves consideration of acute and maintenance treatment, and of the type and severity of illness. For an acute depressive disorder of great severity, or with melancholia or psychosis either electroconvulsive therapy or the combination of antidepressant and neuroleptics may be required. Treatment requires adequate prescribing, patient education, and regular patient monitoring for compliance, symptom change, side effects, and intercurrent medical disorders which may complicate antidepressant therapy. Both antidepressant medications and brief structured psychotherapies, such as interpersonal or cognitive psychotherapies, have efficacy in the acute treatment of elderly depressed outpatients with major unipolar, nondelusional depression. Maintenance treatments are important, however, to prevent relapses or repeated episodes. Treatment recommendations are discussed. The mainstay of treatment for psychotic disorders such as late-onset schizophrenia and late-onset delusional disorder are neuroleptics. Clinical course is variable; maintenance treatments are required. Neuroleptic side effects occur with greater frequency than in younger patients.(ABSTRACT TRUNCATED AT 400 WORDS)