Organic psychoses. Delusional disorders and secondary mania.

Organic delusional disorders and secondary mania are clinical syndromes produced by neurologic diseases and toxic-metabolic disorders. Delusional disorders are associated primarily with limbic system lesions and basal ganglia dysfunction. These two groups of structures are united into a single system involved in the assessment of ongoing perception and experience, and dysfunction in these structures may explain the presence of psychosis. Lesions producing delusional disorders involve dopaminergic projections considered important in idiopathic schizophrenia, and involvement of similar anatomic and biochemical systems may explain the identity of symptoms noted in both disorders. Secondary mania is associated with deep midline lesions and with pharmacologic agents affecting monoaminergic function. Midline lesions may involve reward-system nuclei and euphoriant enkephalins to produce an elevated mood and hypothalamic nuclei to produce alterations in sleep, appetite, and libido. Mania appears to be more common with right-sided than with left-sided lesions. Lesions, metabolic disturbances, and drugs causing mania may disturb serotonergic and noradrenergic transmitters implicated in idiopathic bipolar disease. Study of the organic psychoses is providing insight into the neurophysiologic basis of idiopathic psychotic disorders. Clinically, greater awareness of the organic psychoses may lead to the discovery of additional cases of secondary mania and organic delusional disorders with potentially treatable neuromedical causes.