Obsessive compulsive disorder--a neuropsychiatric illness.

Until recently, obsessive compulsive disorder (OCD) was thought to be a rare condition. Once viewed predominantly as a manifestation of psychodynamic conflict, OCD is now considered a model neuropsychiatric disorder. While clear differences exist between OCD patients and normal controls, there are more similarities between OCD and Tourette's Syndrome than most other neurotic disorders in neurological signs, electrophysiology and neuropsychology. These include a lack of laterality, bilateral or dominant (left) frontal lobe dysfunction, shortened REM latency in sleep electroencephalogram, shortened latency of N200 and P300 components in visual evoked potentials, abnormal glucose metabolism in the caudate nucleus, and greater ventricle to brain ratios in OCD patients. Neuropharmacological and neuroendocrinological researches have increasingly shown that serotonin plays an important role in the complex aetiology in OCD. Finally, psychopharmacological trials have consistently demonstrated the effectiveness of the selective serotonin reuptake inhibitors in the treatment of OCD.