Comparison of interval timing judgement abilities, executive functions and time perception in drug naive first episode major depressive disorder patients and healthy individuals

Introduction: Although there isn't a diagnostic criterion of major depressive disorder (MDD) about change in time perception, depressed patients usually report to perceive time as going by slowly. In addition to changes in subjective time perception, some differences in time interval judgement abilities in MDD are reported. It is suggested that these changes may be related to the effect of patients' internal clock functions. Some authors have suggested that there may be a relationship between changes in subjective time perception and timing abilities in MDD. However, there is conflicting data on this relationship. In our study, we tried to minimize some confounding factors such as pharmacotherapy by preferring drug naive, first episode MDD patients. We also investigated the effects of anxiety and impulsivity levels and executive functions on time perception. Methods: Fifty first episode drug naive MDD patients from psychiatry outpatient clinic and 50 healthy volunteers matched with patient group as age, sex and education level were included in the study. Each participant completed the time production task for 1 s, 3 s, 6 s, 12 s and 15 s after completing the Sociodemographic Data Form, Barratt Impulsivity Scale-11 Short Form and Wisconsin Card Sorting Test (WCST). In addition, the Hamilton Depression Scale, Hamilton Anxiety Scale was administered to the patient group. Visual Analogue Scale (VAS) was used to determine participants' subjective perception of flow of time. Findings: Depresion group experienced slower flow rate of time than controls (p <0.001). In the time production task, MDB group was found to be less successful in producting time intervals (for 3, 6, 12, 15 s ; p = 0.013, p = 0.004, p = 0.004, p = 0.004). Patient group underproduced only 1 s interval (p<0.001). It was seen that the patient group was less successful in the trial number used for completing the first category in WCST (p = 0.035). The motor and total impulsivity scores of the MDD group were significantly higher than controls (p <0.001, p = 0.025). As the subjective time perception accelerates in healthy individuals, shorter times are produced (for 3, 6, 12, 15 s; p= 0.036, p = 0.12, p = 0.026, p = 0.050). This relationship was not seen in the MDB group. Conclusion: Our findings support the phenomenon of slowing in time flow seen in MDD patients. The lack of a relationship between subjective time perception and time-interval judgement abilities may mean that these two concepts are represented in different brain regions. Clarification of mechanisms responsible for time perception may contribute to the explanation of MDD and related symptoms. Questioning the time perception in clinical scales can be helpful to determine the severity of depression.