## 2 Materials and Methods  
The processed data are part of a larger prospective 8-week follow-up study [20]. Hence, 52 initial patients with MDD who addressed or were referred to the '[PERSON]' Psychiatry Clinic Timisoara for psychiatric assistance, were invited to take part in the present study. Of these, two patients subsequently declined to attend all assessment during distinct moments of study. The inclusion criteria were to fulfill Diagnostic and Statistical Manual of Mental Disorders IV \"text revision\" TR (DSM-IV-TR) (American Psychiatric Association, 2000) criteria for Major Depressive Disorder, single or multiple episode, based on Romanian version of Structured Clinical Interview for DSM-IV-TR Axis I Disorders Manual-IV-TR SCID-I [21], aged 18 or above, providing written informed consent. The exclusion criteria were presence of DSM-IV-TR Axis I major psychiatric disorder other than Major Depressive Disorder, presence of pregnancy, the participant is unable to provide informed consent, presence of acute inflammatory disease. The sampling method was by convenience. The recruitment period was between April 2016 and September 2019. At baseline, all patients were assessed for depressive symptoms by administering the 17-item Hamilton Depression Rating Scale (HAM-D) by trained psychiatrists. Also, CRP and IL-6 were measured in blood serum. All sociodemographic, case history and clinical data were collected in the same standardized and unitary manner. The study was approved by the Local Ethics Committee for Scientific Research registration number: 7/01.02.2016 of the Timisoara County Emergency Hospital where the patients were recruited, all subjects providing written informed consent, also respecting the Helsinki Declaration of 1975 regarding research on human subjects. The severity of depressive symptoms was measured by using the 17-item Hamilton Depression Rating Scale (HAM-D). The HAM-D, a clinician-administered depression assessment scale, consists of 17 items pertaining to symptoms of depression experienced over the past week. A score ranging from 0 to 7 is generally accepted to be within the normal or in clinical remission, while a score of 20 or higher is considered indicating at least moderate severity. In our study, the resulted scores were only treated from a quantitative perspective without using a cut-off score [22]. Type D personality (TDP) was surveyed by applying the Type D Scale-14 DS 14 that comprises of 14 items, which is a Likert scale where each item can be scored between 0 = false to 4 = true. Furthermore, the DS-14 scale consists of two subscales representing two distinct dimensions of TDP already described in the introduction section; one is Negative Affectivity evaluated by seven items, and the other is Social Inhibition, which is measured by the other seven items. The total score on each subscale is between 0 and 28. The use of the DS 14 scale is dichotomic, requiring a score \(\geq\) 10 on both subscales to fulfill the D personality condition [23]. Furthermore, based on an extensive cross-cultural equivalence analysis that included 22 European countries and English-speaking countries, the DS14 had good reliability with [PERSON]'s \(\alpha\) between 0.80 and 0.90 for NA and between 0.74 and 0.89 for SI in all countries, except for Russia [24]. For measurement of C-reactive protein (CRP) and interleukin 6 (IL-6), fasting blood was drawn by venipuncture in clot activator vactainer tubes for serum separation. Blood processing and CRP and IL-6 determination in serum was performed in a certified clinical laboratory (Bioclinica Laboratories, Timisoara, Romania). CRP was determined by a latex-enhanced immunoblotting method using the Atellica CH Wide Range C-Reactive Protein assay (Siemens Healthineers, Munich, Germany) according to the manufacturer's recommendations in an Atellica CH Analyzer (Siemens Healthineers). Serum IL-6 levels were determined using a sandwich ELISA method with the Cobas Elecsys IL-6 assay (Roche Diagnostics, Rotkreuz, Switzerland) according to the manufacturer's instructions.