Cognitive trajectories in the nine months following recent-onset major depressive disorder

Specific cognitive difficulties are common in major depressive disorder, impacting functioning and quality of life. Yet, the timing of their emergence and longitudinal course remains poorly understood. This study aimed to characterise longitudinal cognitive functioning following recent onset depression and its association with changes in depressive symptoms.

Longitudinal data from the PRONIA (Personalised Prognostic Tools for Early Psychosis Management) cohort recruited from ten European sites were used to evaluate trajectory differences between Healthy Controls (HC) and individuals experiencing recent onset depression (ROD). Linear mixed effect models were used with group-by-time interaction term for trajectory differences between baseline and nine-month follow-up, and the associations between changes in depression symptoms and cognitive functioning among ROD.

The sample comprised 420 participants (ROD, N = 151; HC, N = 269) aged 15-40 years (M = 25.4, SD = 6.1; 55% female). Two distinct group-level cognitive trajectories were observed. First, a similar trajectory (i.e., no difference) to HC in visual memory, attention span, verbal learning and memory, visuospatial working memory, emotion recognition, and processing speed. A stable deficit trajectory was observed in mental flexibility, auditory verbal working memory, phonetic and semantic verbal fluency among the ROD group. Analysis within ROD group suggested that these outcomes were unrelated to reductions in depressive symptoms. Changes in visual memory, visuospatial working memory, sustained attention, and processing speed were associated with changes in depressive symptoms, despite being unrelated to baseline variations in depressive symptoms, possibly suggesting a sensitivity to state effects of illness, regardless of baseline severity.

Specific cognitive difficulties are already evident at the first depressive episode and may endure in the short-medium term, irrespective of depressive course. Tailored treatment addressing cognition should be provided early to promote cognitive health and functional recovery.