Relation of major depression with reward related learning

Gürcan A., Relation of Major Depression with Reward Related Learning. Hacettepe University, Faculty of Medicine, Department of Psychiatry, Dissertation Thesis, Ankara, 2017. Objectives: Anhedonia is the one of the core symptoms of depression. The anhedonia has influences in the progress and response to treatment of major depression and it's investigated in different dimensions in the context of reward processes in recent years. In this study it was aimed to investigate different dimensions of anhedonia by using scales and a behavioral task with assess reward related learning and relation of these dimensions and other features of depression. Method: Seventy eight outpatients diagnosed with major depression and whose lifelong diagnosis was confirmed by Structured Clinical Interview for DSM-IV (SCID-I) and followed by Hacettepe University Hospital Psychiatry Polyclinic were recruited. Patients who didn't have symptoms which fulfill the criteria of major depression constituted 'Remitted Major Depression' group (RMD, n=40), and patients who had still symptoms which fulfill the criteria of major depression constituted the 'Major Depression' group (MD, n=38). Control Group (C) consisted of healthy individuals who were never diagnosed with any psychiatric disorder. Thirty eight patients who had still symptoms which fulfill the criteria of major depression constituted the Major Depression (MD) group and other forty patients constituted the Remitted Major Depression (RMD) group. Comorbid Axis I mental diagnosis other than remitted anxiety disorders were excluded. Depression severity was evaluated with Beck Depression Inventory (BDI), trait like physical anhedonia was evaluated with Chapman Physical Anhedonia Scale (PAS), trait like social anhedonia was evaluated with Chapman Social Anhedonia Scale (SAS), state like anhedonia was evaluated with Clinician Administrated Snaith Hamilton Pleasure Scale Turkish Version (SHAPS-C-TR), state anxiety was evaluated with State-Trait Anxiety Inventory (STAI) state anxiety subscale, subthreshold bipolarity was evaluated with Hypomania Checklist-32-Revised Version (HCL-32-R) and symptoms of attention deficit hyperactivity disorder were evaluated with Wender Utah Rating Scale(WURS). Reward related learning was evaluated with Probabilistic Reward Task (PRT) which is a behavioral task. While analyzing the data of PRT, quality of the data, depression severity and evaluations about attentions deficit hyperactivity disorder were considered. Data were analyzed with T test, Mann-Whitney U test, Welch ANOVA, Kruskal Wallis test, Pearson test, Spearman test, ANOVA and ANCOVA by using SPSS Statistics 22.0. Significance level was set as p <0.05. Results: Clinician administrated SHAPS-C-TR anhedonia scores of MD group was higher than RMD and C groups. This score which shows state-like anhedonia wasn't correlated. On the other hand, only item of BDI which evaluates loss of pleasure was correlated with SHAPS-C-TR anhedonia score. These results suggested that SHAPS-C-TR is evaluated state-like anhedonia (hedonic capacity). The items of SHAPS-C-TR which were applied to evaluate anticipatory dimension of anhedonia were found invalid. Some participants' PRT data which evaluates reward related learning were excluded by considering BDI and WURS scores and technical quality of the data for PRT. The correlations between scores of anhedonia which evaluated by clinical scales and variables related to response bias weren't moderate or more. For variation of the response bias, there was block effect for all participants (MD n=15, RMD n=35, C n=37) but the groups weren't significantly different. When the whole sample divided by using SHAPS-C-TR anhedonia scores (threshold set as 4) as anhedonics (n=12) and non-anhedonics (n=75) no difference determined between groups. But non-anhedonics group's response bias of block 1 significant different than response bias of block 2 and block 3 group, and in anhedonics group. On the other hand in anhedonic group there was no difference between response bias for following . Conclusion: The results of the study suggest that in major depression, consummatory anhedonia showed state like characteristics, and reward related learning wasn't different from C group. This results need replication with bigger sample sizes. And it showed that impairment in reward related learning might have stronger relations between anhedonia which is evaluated by scales more than diagnosis or history depression. Keywords: Major depression, anhedonia, reward related learning This study was supported by Turkish Psychiatric Association as a part of 21. Turkish Psychiatric Association Annual Meeting and Clinical Education Symposium, 'Research Incentive Award' (Antalya, 19-22 April 2017).