The debates about depressive disorder and cognition impairment are supported by controversial data.

We launched the study to investigate cognitive change in first onset depressive patients over a 6 year period.

A prospective cohort was performed. Participants included 206 cases of first onset depressive Chinese outpatient aged from 17 to 60 year old and followed from Apr. 2003-Feb. 2004 to Apr. 2009-Feb. 2010 in Shanghai. During the first 48 weeks, case management service was delivered. Participants were assessed by 17-HAMD and HAMA scale at baseline, week 12, week 32, week 48, and year 6. Cognitive changes were assessed using the WMS-RC, WAIS-RC, and WCST at baseline (n = 116), week 12 (n = 80) and year 6 (n = 24), 41 normal participants as control.

1. (1) During the first depressive onset, cognitive performance deteriorated comparing with those of control group (P < 0.01).

2. (2) At week 12,effective medication could relieve symptom and improve cognition function (P < 0.05), cognitive performance compared between patient and control with no obvious difference (P > 0.05). While patient group had a significantly larger proportion (whose Memory Quotient below 85) than control group did (χ2 = 5.66, P < 0.05).

3. (3) Using a general linear mixed model to estimate cognitive change,patients with more severe depressive retardation and lower education had a worse short-term memory over 6 years (estimate = -1.65, SE = 0.80, P < 0.05;estimate=1.63, SE = 0.30, P < 0.01), adjusting for demographics and medical status.

The first onset depressive patient has cognitive defects. Memory does not full recovery after symptom relief. Short-term memory impairment persists over 6 years with relative factors.