Investigation of the effects of depression and vitamin d effects on the eye vessels

Introduction and Aim: Although the etiology of depression is not yet fully understood, the causes of depression are based on psychosocial, genetic and biological factors.The inflammatory processes involved in the etiopathogenesis of depression and cytokines affect neurotransmitter metabolism, neuroendocrine functions and synaptic plasticity in the brain.Demonstration of pathological processes in depression by various neuroimaging methods is very important in explaining both etiopathogenesis of depression and monitoring early diagnosis / treatment response. We used optical coherence tomography (OCT), allowing non-invasive imaging of the retina, which is considered to be an extension of the brain in our study.In this study we aimed to investigate: a)whether there is any difference in terms of Vitamin D between major depressive individuals and healthy control groups, b) whether vitamin D deficiency in depressive episodes has an inflammatory effect and an effect on OCT measurements c)whether there is anyincrease in inflammatory processes in major depressed individuals compared to the healthy control group d)whether there is any neurovascular and neurodegenerative changes in major depressed individuals compared to healthy controls which can be demonstrated by the OCT method e) whether there is any difference in terms of inflammatory parameters and OCT measurements between first attack and recurrent depressive patients f) whether the severity of the depressive episode has an effect on the inflammatory parameters and OCT measurements. Method: 24 healthy control groups and 42 drug free major depressed patients matched for age, sex and eye measurements ( axial and spherical equvalans) were compared in terms of vitamin D, CRP and OCT parameters. The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), Hospital Anxiety Depression Scale (HAD), Perceived Stress Scale (ASO), and Global Functional Assessment Scale (IGD) were used to assess disease severity. Findings and Results:The vitamin D level in the major depression group was significantly lower than the healthy control group. CRP levels in the major depression group were significantly higher than in the healthy control group.Choroidal thickness in the major depression group is significantly higher than the healthy control group and the ganglion cell layer is significantly lower than the healthy control.There was no difference in CRP between vitamin D sufficient andVitamin D deficient majör depressive patients.There was no difference between the OCT parameters of vitamin D sufficient and vitamin D deficient major depression groups.In the first episode of major depression, choroidal thickness was higher compared to recurrent major depression, but this difference disappeared when age was controlled.IPL and nasal retinal thickness of patients with male major depressive patients were significantly higher than those of female major depressive patients. In major depressive patients, negative correlation was found between the current episode duration and GCL volume and RET.N. There was also a positive correlation between depression severity and CRP.Negative correlation was found between HADD and HAMA-psychic and GCL volume in major depressives.Low level of education predicted being a depressive patient and a higher HAMD score in regression analysis in all participants. CRP level was predicted by depressive episode duration and low level of Vitamin D in all participants. In majör depressive patients, RFNLG was predicted by age in a positive way. CRP level in majör depressive patients was predicted by lower funcitonality and longer depressive episode duration. Discussion: CRP levels in major depressive patients were significantly higher than healthy control group, supporting the previous studies showing that major depression is associated with inflammation. In addition, vitamin D levels were found to be significantly lower in major depressive patients than healthy controlswith a negative correlation between depression severity and vitamin D level. These findings indicate the importance of Vitamin D replacement in major depressive patients. Choroidal thickness was significantly higher than healthy control group ,indicating an increase in retinal blood flow due to inflammatory processes in the major depression. Also, in major depressive patients,ganglion cell layer volume is reduced compared to the healthy control group, which may indicate neurodegeneration in the major depressive disorder. Negative correlation between current attack duration and GCL volume and RET.N in major depressive patients and negative correlation between HADD and GCL volume may show the effect of disease duration and severity on neurodegeneration. Conclusion: It has been shown that major depression is a disease which neuroinflammatory and neurodegenerative processes are observed with OCT and CRP measurements and the long duration of untreated disease, increased disease severity and low vitamin D level negatively affects these processes. OCT measurements are influenced by factors such as age, sex, so it may be more useful to conduct future studies as a follow-up study controlling these factors. Key words: major depression, Vitamin D, CRP, optical coherence tomography