MRI Study Of Cerebral Blood Flow Differences In Patients With BD-Ⅰ In Depression And BD-Ⅱ In Depression By Using The Technique Of Arterial Spin Labeling

Background:Little is known about the neural differences about bipolar disorder type Ⅰ (BD-Ⅰ) and bipolar disorder type Ⅱ (BD-Ⅱ). Some studies have found that different phases in bipolar disorder (BD) present different changes in cerebral blood flow (CBF). Changes in the CBF may reflect the differences between the two subtypes of BD. Studies of positron emission tomography (PET) and single photon emission computed tomography (SPECT) have shown neuropathological changes in the CBF of BD. Arterial spin labeling (ASL) imaging is a noninvasive technique to detect CBF that has been broadly used in depression studies and may become an effective way to illustrate the neural mechanism of bipolar disorder type Ⅰ in depression (BD-Ⅰ-D) and bipolar disorder type Ⅱ in depression (BD-Ⅱ-D).Objectives:Using the technique of ASL to confirm the differences of CBF between BD-Ⅰ-D and BD-Ⅱ-D and to provide biological evidence to differentiate BD-Ⅰ and BD-Ⅱ as well.Methods:The current study was conducted in 45 patients with bipolar depression diagnosed by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR) and 23 healthy controls, including 21 bipolar disorder type Ⅰ patients in depression (BD-Ⅰ-D) and 24 bipolar disorder type Ⅱ patients in depression (BD-Ⅱ-D). All subjects were scanned by 3D T1 and ASL sequences. Two sample t-test was applied to compare the CBF maps of the two subtypes and healthy controls separately, as well as between the two subtypes. For patients groups, the results of the CBF maps of the three groups were analyzed and multiple regression analysis was used to correlate CBF changes in the caudate, the anterior cingulate cortex (ACC) and the prefrontal cortex (PFC) separately with age, education years, Mood Disorder Questionnaire (MDQ) scores and Hamilton Rating Scale for Depression (HAMD) scores.Results:Compared to healthy controls, BD-I-D patients show a higher CBF in the two-sided caudate head while there was no significant difference between BD-Ⅱ-D patients and healthy controls (P>0.05). BD-Ⅰ-D patients had a higher CBF in the left caudate and the ACC than BD-Ⅱ-D patients (P<0.05, corrected by AlphaSim, cluster size>248). By using multiple regression analysis, we found significantly negative correlation between changes of CBF in the caudate and the ACC with HAMD scores in bipolar disorder patients (P<0.05), which suggested that HAMD scores may be the only one predictor for CBF change of caudate (a-R2=0.113, P=0.014) and the ACC (a-R2=0.082, P=0.032). However, we found no significant correlation between CBF changes in both the caudate, the ACC and the PFC VS (age, education years and MDQ scores) (P>0.05), as well as the HAMD scores with the change of CBF of the PFC.Conclusions:ASL is sensitive to distinguish BD-Ⅰ and BD-Ⅱ, as well as BD-I patients from healthy controls; it could help the identification of CBF as a biomarker to differentiate BD-Ⅰ from BD-Ⅱ. The degree of depression may influence the CBF.