Late-onset obsessive-compulsive disorder associated with left cerebellar lesion.

The onset of obsessive-compulsive disorder (OCD) after age 50 is rare and generally related to an organic etiology. An involvement of fronto-striatal circuits has been strongly suggested, whereas cerebellum remains so far scarcely explored. We present here the description of a "pure" late-onset OCD associated with a cerebellar lesion, neither comorbid with other mental disorders nor with neurological syndromes. To our knowledge, this condition was not previously described in literature. The patient is a 62-year-old woman who developed a late-onset OCD associated with a left cerebellar lesion due to an arachnoid cyst in the left posterior fossa. We debate the possible role of the cerebellar lesion in favoring a transition from a predisposing liability (namely an obsessive-compulsive personality disorder and a depressive status) to the onset of OCD in this woman.