The Brain Activation And Emotional Responses Of Postpartum Depression Patients During Resting And Task State

Postpartum depression (PPD) is a common perinatal mental illness occurred in puerperium mainly suffering from depression. So far, the study of the disease remains on the social and psychological factors and hormones levels, the pathogenesis mechanism of PPD especially in brain is still not clear. The rapid development of brain science and functional imaging technology in the last decade makes us study its neuropathy basis possible.Using functional magnetic resonance(fMRI), scale, and endocrine measurement methods, this study investigated the brain function of PPD on resting and task-state.The study comprised three parts:(1) The study of the fMRI differences between the postpartum group and the maternal control group under resting state.(2) The study of PPD’s negativity bias and its brain mechanisms.(3) The study of PPD’s subjective stress evaluation, cortisol levels and brain mechanisms under stress.Through the studies of PPD’s brain function under the resting state under the state, we desired to provide a theoretical and experimental basis for pathological mechanism of PPD.Experimental methods:(1)12patients with postpartum depression and11maternal control subjects accepted functional MRI scans for six minutes under resting state, the imaging datas were analyzed using regional homogeneity (Reho) method, compared the Reho differences between postpartum depression group and maternal control group.(2)11patients with postpartum depression and11maternal control subjects accepted functional MRI scans for nine minutes under positive and negative music, using SAM scale to evaluate the pleasure valence during hearing the music, compared the pleasure levels and the brain function differences between postpartum depression group and the maternal control group.(3)10PPD patients and10maternal control subjects were scanned on three levels of mental arithmetic stress, using stress scale assessed the subjective stress levels, using enzyme-linked immunosorbent assay measured saliva cortisol levels, compared the subjective stress level, cortisol and brain function differences between the postpartm patients and the maternal controls. The data were dealt with analysis of variance, t test, chi-square test etc. After detailed analysis and discussion; the study reached following conclusions:Abnormal Reho was found in PPD patients in resting-state state. The Reho of left and right posterior cingulate gyrus, right anterior cingulate gyrus, right anterior prefrontal lobe was significantly increased in PPD patients compared with maternal controls. The Reho of right superior temporal gyrus, middle temporal gyrus, and inferior temporal gyrus, left and right insula significantly decreased in PPD patients compared with maternal controls. These abnormal brain regions were mostly located in the brain default network, suggesting that the default networks of postpartum depression patients was abnormal.(2)We found negative bias in PPD patients. To positive music, PPD patients showed significantly increased right caudate nucleus, inferior parietal lobule, left inferior temporal gyrus etc. activation in PPD patients compared with maternal controls, and showed decreased positive emotion. To negative music, PPD patients showed significantly increased bilateral hippocampus, right insula, right caudate, right putamen, left inferior parietal lobule and left inferior temporal gyrus, etc. and showed increased negative emotion. To negative music, correlational analyses revealed were negative correlation between the pleasures levels and the music-related right hippocampus activity in depressed mothers. The abnormal activation of these brain regions may be the brain pathology basis of negative bias.(3) The PPD patients showed no different subjective stress evaluation to low level arithmetic stress with maternal control, but showed increased subjective stress level to middle and high level of mental arithmetic. With the mental arithmetic level increasing, this difference appeared more apparent. The PPD patients showed higher cortisol baseline than the maternal control, but under stress, the elevated cortisol was lower than the maternal control group. Under stress, the PPD patients showed increased bilateral putamen, left hippocampus, left prefrontal lobe (BA44,45) etc.brain activation compared with the maternal control. And correlational analyses revealed positive correlation between the subjective stress levels and the stress-related left putamen activity in depressed mothers.The abnormal psychological, endocrine and brain dysfunction may play a role in the disease’s pathology.(4)The abnormal brain function changes and emotional response of postpartum depression patients during resting and task-state were not entirely consistent with the general depression, suggesting that postpartum depression has a different brain functional feature.