Brain Imaging, Genetics and Treatment for Major Depression

Objective: Major depressive disorder (MDD) is a serious, debilitating, life-shortening illness that affects many persons of all ages and backgrounds. Although many patients suffering from MDD can expect improvement with antidepressant treatment, only a minority experience full remission, and little is known about the basis for individual differences in treatment outcome. The rationale for this study follows from the findings that treatment response in major depression is associated with: 1) variation in the genes encoding the serotonin 2A receptor (HTR2A) and the KA1 subunit of the glutamate-kainate receptor (GRIK4); and 2) increases in prefrontal glutamate/glutamine (glx) concentration measured by \[+H\] magnetic resonance spectroscopy (MRS). The central hypothesis is that genes associated with citalopram treatment outcome modulate glutamate concentrations in prefrontal brain (PFB) and thus facilitate response to citalopram treatment. Such information is important because it would ultimately allow the development of better treatments for MDD. Study population: A total of 104 moderate to severe MDD outpatients aged 25-55 with a baseline 17-item Hamilton Depression Rating Scale (HDRS) score of greater than or equal to18 who meet DSM-IV criteria for non-psychotic major depressive disorder (MDD) will be enrolled in the course of the study. Design: Subjects will be screened with an on-site research psychiatric evaluation using a structured interview (MINI plus). After screening, participants will provide a DNA sample, which will be analyzed to determine the patient s genotype at several relevant loci. All patients will then complete an eight-week period of citalopram treatment, during which time they will be evaluated bi-weekly with self-report questionnaires and clinician ratings to determine change of MDD symptoms. Participants will also undergo pre- and post-treatment MRS scans to determine glutamate concentration in the prefrontal brain. Treatment outcome measures: The Quick Inventory of Depressive Symptomatology - Clinician-Rated (QIDS-C16) will be the primary clinical outcome measure and will be collected at baseline and at each treatment visit. Additionally, levels of glutamate in the prefrontal regions of the brain will be measured by MRS. Clinical response will be defined as a decrease of 50 percent or greater in QIDS-C16 score from baseline, and remission will be defined as a QIDS-C16 score of less than 6. This proposal is part of a K99 training grant and has undergone extensive external review (K99MH085098-01A2).