Change of fractional amplitude of low frequency fluctuation in untreated primary insomnia patients: a resting state functional magnetic resonance imaging

Abstract

Objective The aim of this study is to understand the impairment and compensation mechanism of brain function in untreated primary insomnia (PI) patients. The approach of fractional amplitude of low frequency fluctuation (fALFF) is used to analyze raw data between the PI patients and the normal control group in resting state using functional magnetic resonance imaging (fMRI). Methods Fifty-nine PI patients, admitted to our hospital from November 2015 to November 2016, and 47 age-, education-, and gender- matched normal healthy subjects were chosen in our study. Pittsburg sleep quality index (PSQI), insomnia severity index (ISI) were employed to evaluate the sleep quality. Self-rating anxiety scale (SAS) and self-rating depression scale (SDS) were employed to evaluate the emotion. Resting state fMRI and fALFF analyses were used to compare the functional regional activities. The correlations of fALFF data with PSQI, SAS and SDS scores were analyzed. Results In PI patients, 2 had mild to moderate insomnia, 41 had moderate insomnia, and 16 had serious insomnia. ISI scores in the normal healthy subjects were less than 7. The PSQI, SAS, SDS and ISI scores in the PI patients were significantly higher than those in the normal healthy subjects (P<0.05). As compared with the control group, the PI group had significantly increased fALFF value in the right hippocampus (HIP), right parahippocampa gyrus, right amygdala, and bilateral thalamus. The fALFF value was positively correlated PSQI, SAS and SDS scores (r=0.582, P=0.000; r=0.617, P=0.000; r=0.653, P=0.000). Conclusion Some brain regions in the PI patients are abnormal in the resting state, which can reflex functional regional activities of PI patients. Key words: Primary insomnia; Resting state; Functional magnetic resonance imaging; Fractional amplitude of low frequency fluctuation