Comparision of hippocampus volumes between early onset recurrent major depressive disorder patients with high genetic risk and healthy controls

INTRODUCTION: MDD is the most common affective disorder in society which can cause severe morbidity and even mortality. It is known that both genetic and environmental factors play role in MDD but the whole pathophysiology has not been clarified yet. In neuroimaging studies it has been shown that the most volume reduction occurs in hippocampus. It is supposed that clear information about pathophysiology would be reached by clarifying the changes in the whole brain, especially in hippocampus. In a study done by our research group, comparison of hippocampus volume in control group and a group of women who have high genetic risk for MDD. As a result, it has been shown that there is no difference in total hippocampus volume but some differences attract attention which are thought to be related to premorbid genetic predisposition. In this study, comparisons of hippocampus volume and hippocampus subsection volume have been done in two groups, one of them is a group of women whose ages are between 19 and 25, who have high genetic risk for MDD and have at least two MDD episodes and one of these episodes must occur under age 19, and the second group is control group. METHOD: 27 patients, with at least two MDD episodes, at least one episode under age of 19, with depressed mothers and 19-25 years of age and 29 healthy controls equal to the patient group in terms of age and education level have beeen included in this study. Informed consent form has been signed and detailed psychiatric examination has been done to the volunteers who agree with the criteria and agree to participate in the study. In addition to psychiatric examination, Structured Clinical Interview for DSM IV (SCID-I), Hamilton Depression Rating Scale(HAM-D-17), Beck Depression Inventory, Beck Anxiety Inventory, State Trait Anxiety Inventory (STAI) and Childhood Trauma Questionnaire (CTQ) have been conducted. Subsequently MR images have been obtained by using 3 Tesla MR devices and images obtained with 3D T1 weighted MP-RAGE sequences have been used for region of interest analysis. Volumes of hippocampus and hippocampus subsection have been measured with FreeSurfer software package. CONCLUSION: There has been no significant difference in left and right total hippocampus volume and hippocampus proper volume between depression group and control group. Right HPV has tended to shrink in depression group. Effects of age, education level, total intracranial volume and group on all volumes have been evaluated by using general linear model. The volume of the right CA1 body region has been found significantly lower in patient group comparing to control group (F(1,51)=7,160 p=0,010). Both total and body volumes of right presubiculum have been found significantly higher in patient group (F(1,51)=5,222 p=0,026; F(1,51)=4,099 p=0,048). Total volume of right CA2/3 region has been found significantly lower in patient group ( F(1,51)= 4,190 p=0,046), in addition to this body region has tended to shrink ( F(1,51)=4,000 p=0,051).Other subsection volumes has not been significantly different between groups. Regression analysis has been performed with the factors thought to be effective for the regions determined to be different and according to analysis HAM-D score (p = 0.012, r2 = 0.131) and TIV (p = 0.016, r2 = 0.97) have been significantly effective on right CA1 body volume; TIV (p = 0.004; r2 = 0.1117) and CTQ (p = 0.06; r2 = 0.123) have been significantly effective for the right presubiculum body volume; TIV (p <0,01, r2 = 0,340) and age (p = 0,047, r2 = 0,051) have been significantly effective for total volume of CA3. DISCUSSION AND CONCLUSION: It is believed that our study has contributed to literature not only by clarifying pathopysiology and improving our knowledge about MDD which has high disease burden, but also by developing methods which can predict which treatment work in which patient. Long-term follow-up studies with wider sampling in multiple centers should be done so as to get more precise information, explain cause-result relations and reduce the impact of recall factor.