Using different types of visual reaction time measurements for assessing cognitive difficulties in depression

There is a need for objective, easy and relatively short methods to diagnose cognition in depression. We have constructed a set of simple visual tasks using three different ways of speed measuring: paper-pencil-based, computer-based, and eye-tracking based. We used a single case design with 22 participants. A clinical group counted 11 patients with major depression examined two times (first examination without medication and second after three months of medical treatment) together with a group of 11 matched healthy controls. Cognitive difficulties were observable in all the checked levels of performance. The weakest in all tasks were patients before medication, some improvement was observed after medical treatment, but not matching the level of healthy controls. Cognitive difficulties were not eliminated by medical treatment as quickly as emotional disturbances were. The observed difficulties could be interpreted in terms of psychomotor retardation, a typical symptom in depression, which proved to be mainly cognitive as the analysis of differences in reaction times and the first saccade latencies concluded. The analysis of simple visual reaction times on several stages turned out to be a promising method to measure the cognitive state in persons with mood disorders and cognitive convalescence during major depressive disorder treatment.