Principles of neuropsychiatry: Towards a neuropsychiatric epistemology

Depression, mania, obsessive-compulsive behavior, psychosis and personality changes are common manifestations of brain disorders. These neuropsychiatric syndromes exhibit rule-bound relationships to brain dysfunction and occur most commonly with lesions of the limbic system or frontal-subcortical circuits. They reflect disruption of mechanisms mediating fundamental functions such as mood, emotion, motivation, self-protection and social affiliation. Lesional factors (i.e. size and location of lesion, disruption of transmitter systems) as well as host-related non-lesional factors (i.e. family history of psychiatric illness, age of onset of neurological condition, gender) contribute to determining which patients with specific neurological conditions develop associated neuropsychiatric disturbances. Investigations of the psychiatric aspects of neurological disease and the neurobiology of psychiatric disorders indicate that similar anatomical regions are involved when these conditions have the same symptoms. These principles comprise the basis of an evolving neuropsychiatric epistemology.