The present study is the first clear demonstration of EEG changes during REM sleep in iRBD patients in whom EEG power spectrum seems to be characterized by a lower degree of difference from that of stage 2 (vs. normal controls) and by a higher degree
of instability. Moreover, chronic treatment with clonazepam seems to be able to revert only partially these changes.
Fantini et al. were the first to report that, compared with controls, untreated iRBD patients had a lower spectral EEG power in the beta band, over the occipital regions during REM sleep. However, the observed effects were of marginal statistical significance
and some methodological flaws affected their results because their beta1 band included some sigma band frequencies, with the remaining sigma band frequencies included in the alpha band. Iranzo et al. tried to replicate the study by Fantini et al. and extended the analysis to untreated iRBD patients with mild cognitive impairment but used the same frequency bands. These authors only found, in REM sleep, small increases in power of the theta and beta2 bands in iRBD patients versus controls, in the C4 EEG channel,
but a decrease in the beta 1 band in the O1 lead. More significant changes were found for iRBD with mild cognitive impairment.
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