Brain perfusion anomalies in rapid eye movement sleep behavior disorder with mild cognitive impairment

Rapid eye movement (REM) sleep behavior disorder is an important risk factor for Parkinson's disease and dementia with Lewy bodies. Approximately 50% of patients with REM sleep behavior disorder have mild cognitive impairment. Our objective was to investigate brain perfusion changes associated with mild cognitive impairment in REM sleep behavior disorder. Twenty patients with REM sleep behavior disorder, including 10 patients with mild cognitive impairment and 10 patients without mild cognitive impairment, and 20 healthy controls underwent a complete neuropsychological assessment and single-photon emission computerized tomography using (99mc) Tc-Ethylene Cysteinate Dimer. Compared with controls, both REM sleep behavior disorder groups had hypoperfusion in the frontal regions. In addition, patients with REM sleep behavior disorder and mild cognitive impairment showed cortical hypoperfusion in the occipital, temporal, and parietal regions compared with controls and patients with REM sleep behavior disorder without mild cognitive impairment. Both REM sleep behavior disorder groups had hyperperfusion in the right hippocampus and parahippocampal gyri. However, patients with REM sleep behavior disorder and mild cognitive impairment showed more pronounced anomalies in the right hippocampus and had increased perfusion in the putamen and the left paracentral gyrus. This study showed specific patterns of posterior cortical hypoperfusion and hyperperfusion in some brain areas in patients with REM sleep behavior disorder and mild cognitive impairment, similar to those found in Parkinson's disease dementia and dementia with Lewy bodies. This suggests the presence of an identifiable neuroimaging marker of synucleinopathy in REM sleep behavior disorder with mild cognitive impairment. © 2012 Movement Disorder Society.