Evaluation of the Age-related and Gender-related Differences in Patients with Primary Insomnia by Fractional Amplitude of Low-frequency Fluctuation: A Resting-state Functional Magnetic Resonance Imaging Study

Insomnia patients with different gender and age usually had different sleep experience. Primary insomnia (PI) has been considered to be a disorder of hyper-arousal in the physiologic, emotional, or cognitive network. Although the hyper-arousal brain regions can be shown by comparing the brain activity of PI patients with normal people at rest, whether the brain activity of PI patients varied according to age and gender and whether age and gender could affect the distribution of hyper-arousal brain regions are still worthy of further exploration. Hence, a resting state functional magnetic resonance imaging study (No. NCT02448602) was designed to observe the brain activity of thirty PI patients and 15 healthy controls (HCs). The brain activity in resting state was measured by calculating the fractional amplitude of low-frequency fluctuations (fALFF), which reflected the idiopathic activity level of neurons. Multiple regression was performed to investigate the age and gender-related differences of brain activity in PI patients (P < .001, Family Wise Error (FWE) correct P = .05, cluster size >50) with age and gender as covariates. The hyper-arousal brain regions were measured by comparing the fALFF of PI patients and HCs. Multiple regression (P < .001, FWE correct P = .05, cluster size >50) was also performed for PI patients and HCs with group, age, and gender as covariates.The results suggested that the gender-related difference of brain activity mainly existed in superior temporal gyrus, cerebellum posterior lobe, middle frontal gyrus, and the age-related difference mainly existed in cerebellum anterior lobe, superior temporal gyrus, brainstem, parahippocampa gyrus, anterior cingulate, cingulate gyrus. In addition, the altered fALFF regions between PI and HCs mainly existed in superior temporal gyrus, posterior cingulate, anterior cingulate, cingulate gyrus, middle frontal gyrus. Furthermore, the gender factor could not influence the distribution of the altered regions. While the age factor could affect the distribution of the altered regions.