The neuropsychiatry of multiple sclerosis.

This review describes the many neuropsychiatric abnormalities associated with multiple sclerosis (MS). These may be broadly divided into 2 categories: disorders of mood, affect, and behaviour and abnormalities affecting cognition. With respect to the former, the epidemiology, phenomenology, and theories of etiology are described for the syndromes of depression, bipolar disorder, euphoria, pathological laughing and crying, and psychosis attributable to MS. The section discussing cognition reviews the prevalence and nature of cognitive dysfunction, with an emphasis on abnormalities affecting multiple domains of memory, speed of information processing, and executive function. The detection, natural history, and cerebral correlates of cognitive dysfunction are also discussed. Finally, treatment pertaining to all these disorders is reviewed, with the observation that translational research has been found wanting when it comes to providing algorithms to guide clinicians. Guidelines derived from general psychiatry still largely apply, although they may not always be most effective in patients with neurologic disorders. The importance of future research addressing this imbalance is emphasized, for neuropsychiatric sequelae add significantly to the morbidity associated with MS.