Low-frequency Amplitude Study Of Brain Activity In Different Phases Of Bipolar Disorder

Purpose:Bipolar disorder(BD)is a group of chronic psychiatric disorders with both manic or hypomanic episodes and depressive episodes.Since the symptoms are relatively mild during the mild manic episode and the impairment of social function is not obvious,patients and family members may easily overlook it and lead to the missed diagnosis.Therefore,it is meaningful to look for the biological characteristics of the different phases to identify BD.The low frequency fluctuation in resting-state functional magnetic resonance imaging(rs-f MRI)mainly comes from neurons and reflects the state of intrinsic brain function activity,in which the amplitude of low frequency fluctuation(ALFF)reflects the state of the brain function.ALFF reflects the intensity(energy)of neural activity and is a common method to study biological properties.Therefore,the observation of ALFF in BD with different phases(depressive phase and hypomania phase)and healthy controls can provide a reference basis for BD diagnosis and intervention.Methods:24 patients with depressive episodes and 21 patients with hypomania episodes who met the bipolar disorder diagnostic criteria of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders,Fifth Edition,were selected for the study,and 25 healthy individuals were used as the control group.Resting-state functional MRI data were collected and calculated ALF on the conventional frequency band(0.01-0.08Hz)and five frequency bands(slow-6:0-0.01 Hz,slow-5:0.01-0.027 Hz,slow-4:0.027-0.073 Hz,slow-3:0.073-0.198 Hzand slow-2:0.198-0.25Hz).(1)Obtain mALFF maps and perform one-sample t-test to observe the functional brain activity of BD patients in different time phases;observe the difference between groups by two-sample t-test.(2)One-sample t-test was performed to observe the significant spatial distribution within groups in different frequency bands;then a two-way repeated measures ANOVA was used to obtain significant interaction effects between groups and frequency bands,and a t-test was performed to observe the differences between groups for the mean ALFF values of the three groups in different frequency bands.(3)Correlation analysis was used to analyze the correlation between clinical symptoms,age and frequency bands.Results:(1)Changes in brain function in different phases.The depressive phase showed altered brain function in the anterior,medial,and paracentral cingulate,superior frontal gyrus,precuneus,and insula;the hypomanic phase showed altered brain regions in the medial cingulate,superior frontal gyrus,and inferior frontal gyrus.(2)Differences in brain activity from different phases.Bilateral inferior frontal gyrus and left precuneus depressive phase showed significant brain activity alteration;significant brain function alteration in hypomania was shown in bilateral middle frontal gyrus,bilateral inferior frontal gyrus and left paracentral lobule;no significant difference between depressive phase and hypomania.(3)Group frequency band and the interaction of group and frequency band.1)In the depressive phase,the significant effects of group were mainly concentrated in the postcentral gyrus,middle frontal gyrus,precuneus and other regions;the significant regions of the significant effects of frequency band were in the brain regions of inferior parietal marginal angular gyrus,precuneus and angular gyrus;the significant brain regions of the interaction effects of group and frequency band were only shown in the right superior frontal gyrus,where age was correlated with slow-6(r=0.416,P<0.05);2)The analysis of light mania showed that the significant effect brain areas of group were mainly distributed in the posterior cingulate gyrus,medial superior frontal gyrus,inferior orbital frontal gyrus,and supplementary motor area;the significant effect of frequency band was mainly concentrated in the superior limbic gyrus,angular gyrus,superior parietal gyrus,precuneus,and middle occipital gyrus;while significant group and frequency interaction effects were observed in the right inferior frontal gyrus,right precentral gyrus,and left anterior cingulate gyrus.(3)No frequency specificity was found in the depressive phase group compared with the light manic group in each frequency band.(4)BRMS within the light manic phase correlated with ALFF.(r=0.451,P=0.04).Conclusions:(1)The frontal-limbic system plays an important role in BD emotion regulation.(2)We found a frequency dependence by observing ALFF in different frequency bands.