REM sleep behavior disorder--psychiatric presentations: a case series from the United Kingdom.

Rapid eye movement sleep behavior disorder (RBD) has rarely been associated with a psychiatric condition. We report a series of cases of RBD presenting as psychiatric disorders. These patients were assessed at a specialist sleep disorders center and investigated using polysomnography and, where appropriate, magnetic resonance imaging of the brain and neuropsychological tests. These cases of RBD highlight the varying presentations and causes of RBD that may involve psychiatrists, sleep specialists, and primary care physicians. These include idiopathic RBD presenting as depression, antidepressant-induced RBD, and a patient with undiagnosed Parkinson disease presenting with RBD. There is an increasing body of knowledge about RBD. At least 10% of patients with RBD are likely to present with psychiatric symptoms. It is essential that the condition is recognised and distinguished from other causes of sleep interruption. After recognizing the disorder, it is essential that the clinician undertake a thorough assessment, including a sleep history and formal investigation of sleep patterns at a specialized unit.