**4. Secondary rapid eye movement sleep behavior disorder (non-synucleinopathy)**

Other causes of RBD include neurologic disorders stemming from structural lesions such as pontine stroke or multiple sclerosis plaques. This can also rarely occur in the setting of progressive supranuclear palsy, Alzheimer's disease, and Huntington disease among others. RBD can coexist with narcolepsy in 50% of patients. Medications that can precipitate RBD include antidepressants such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclics, and monoamine oxidase inhibitors (MAOi). Some beta blockers have also been identified as culprits.
