Implication of Fast Activities of Spectral Analysis in Subjective Sleep Complaints of Elderly Women.

OBJECTIVE: In elderly patients, women have better qualities of sleep than men in objective parameters; however, women subjectively complain more about sleep disturbances than men. We performed visual scoring and spectral analysis of sleep electroencephalograms to explain these gender differences in the degree of arousal, the most representative marker in insomnia. METHODS: A total of 354 participants (≥60 years old) were recruited from a Korean community underwent nocturnal polysomnography (NPSG). A Fast Fourier transform was used for the spectral analysis of the NPSG data. Relative power was calculated as absolute power of each band divided by total absolute power. Difference in total sleep time (D_TST) is obtained by subtracting the total sleep time reported in Pittsburgh Sleep Quality Index (PSQI) from the TST measured by the NPSG. RESULTS: A total of 75 participants (women, 51) were finally analyzed. Women had higher PSQI, longer sleep latencies, sleep inefficiencies, and daytime dysfunctions compared to men. The percentage of stage 1 sleep was higher in men versus in women, whereas percentage of stage 3 sleep was higher in women than in men ( P = .001; P = .001). Women had higher relative alpha and beta powers than men during nonrapid eye movement (NREM) sleep ( P = .017; P = .015). During NREM sleep, beta power was negatively correlated with D_TST ( R = -0.250, P = .033), and relative alpha power in stage 3 sleep was positively correlated with sleep latency in PSQI ( R = 0.267, P = .022). CONCLUSION: Spectral analysis showed that women had more disturbed sleep than men. The result from the spectral analysis may explain hyperarousal in elderly women.

Progression of cognitive impairments in idiopathic REM sleep behaviour disorder.

BACKGROUND: Idiopathic REM (rapid eye movement) sleep behaviour disorder (iRBD) has been implicated in cognitive impairments, but there is little evidence about progression of cognitive dysfunction in iRBD. METHODS: A retrospective follow-up study with patients with iRBD was performed. Conversion to neurodegenerative disorders was analysed by Kaplan-Meier survival analysis. Neuropsychological test results at baseline were compared between patients with iRBD and healthy controls. 57 patients with iRBD were successfully followed up for changes of cognitive performance over time (follow-up duration 50.84±25.38 months; range 12-108 months). Factors affecting cognitive decline were evaluated with multiple regression analysis and the subgroup analysis for groups with and without conversion was carried out. RESULTS: Among 84 patients with iRBD, conversion occurred in 18 patients and conversion rates were estimated to be 9%, 18% and 35% at 3, 5 and 6 years from diagnosis of iRBD. Individuals with iRBD showed lower z-scores at baseline than controls in Mini-Mental Status Examination, Trail Making Test A, constructional praxis and Executive Clock Drawing Task (CLOX2). Patients with non-converting iRBD showed significant performance decline in memory (p=0.003, Digit span forward) and a worsening tendency of executive functions (p=0.007, frontal assessment battery; p=0.012, Stroop test) at follow-up tests. Cognitive decline was associated with disease duration or follow-up duration, and lower executive function at baseline increased conversion risk (p=0.031). CONCLUSIONS: Patients with iRBD have cognitive impairments at baseline and progressive cognitive decline over time. Even in idiopathic cases without development of any neurodegenerative disease, degenerative changes in cognition seem to be under way.