Suspected REM Sleep Behavior Disorder in an Older Adult
A 68-year-old man is brought by his wife because of 2 years of "acting out dreams." He kicks, punches, and shouts during sleep, occasionally injuring himself or his wife, and he recalls vivid dreams of being chased. Episodes occur in the second half of the night. He has no daytime sleepiness, no snoring, and no leg discomfort. Neurologic exam is normal except for mild hyposmia and subtle slowed finger tapping. He takes sertraline for depression. His wife asks whether this is just "normal aging" and whether he needs a sleep study.
1. What is the leading diagnosis and the key differential, and how does his medication complicate interpretation?
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The leading diagnosis is probable REM sleep behavior disorder (RBD): dream-enactment behaviors in the second half of the night with injury and dream recall, in an older man. The differential includes non-REM parasomnias (confusional arousals, sleepwalking-usually earlier in the night), nocturnal seizures, obstructive sleep apnea with confusional arousals, and trauma. SSRIs such as sertraline can cause or unmask RBD-like behaviors, so medication-related RBD must be considered; however, his hyposmia and subtle motor signs raise concern for an underlying synucleinopathy. The combination of RBD features plus prodromal neurologic signs warrants neurologic follow-up.
2. Does he need a polysomnogram, and what would you look for?
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Yes-an in-laboratory video-polysomnogram with REM sleep without atonia (RSWA) assessment is appropriate to confirm RBD, exclude mimics such as OSA or NREM parasomnia, and evaluate for seizures if the history is atypical. Look for elevated chin and limb EMG tone during REM, dream-enactment behaviors captured on video, and any apnea/hypopnea. Note that antidepressants can increase RSWA, so the study should be interpreted in that context. A negative study does not fully exclude RBD, and repeat testing may be considered.
3. How would you counsel him about prognosis and management?
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Explain that RBD is strongly associated with future development of a synucleinopathy (Parkinson disease, dementia with Lewy bodies, multiple system atrophy), though conversion takes years and not everyone converts. Recommend neurologic follow-up and discussion of research or biomarker options if available. For safety: remove weapons or dangerous objects from the bedroom, use a bed rail or separate beds if needed, and consider melatonin as first-line pharmacotherapy, with clonazepam as an alternative in selected patients (caution in older adults and those with OSA or falls). Review whether sertraline is contributing and coordinate with his psychiatrist before any change.