Association between severity of depression and self-perceived cognitive difficulties among full-time employees

To assess the relationship between self-perceived deficits in cognition and severity of depression reported by individuals in full-time employment.

Individuals ≥ 18 years of age employed full-time with diagnosed depression excluding bipolar disorder (participants had to be told by a doctor that they had depression based on DSM-IV criteria) completed a 25-minute Web-based survey in February 2010 (study population identified by Harris Interactive, Rochester, New York). The survey used the Perceived Deficits Questionnaire (PDQ) to assess self-perceived cognitive impairment and the 9-item Patient Health Questionnaire (PHQ-9) to assess depression severity. The 20-question PDQ was used to assess self-perceived cognitive difficulties within the domains of prospective memory, retrospective memory, attention/concentration, and planning/organization (range, 0-20: higher scores indicate greater impairment). Subjects answered how often they experienced such difficulties during the previous 4 weeks (0 = never, 1 = rarely, 2 = sometimes, 3 = often, 4 = almost always). The scale ranges from 0-20 for each of the 4 subscales, with higher scores indicating greater cognitive impairment. The impact of depression on PDQ scores was assessed using a trend test based on an analysis of covariance controlling for potential confounders.

Subjects (N = 1,051) (58% women) had a mean ± SD age of 47 ± 12 years; 38% held professional employment. PHQ-9 scores indicated that 423 employees (40.3%) had no depressive symptoms at the time of the survey, 319 (30.4%) had mild depression, 166 (15.8%) had moderate depression, 82 (7.8%) had moderately severe depression, and 61 (5.8%) had severe depression. Perceived cognitive functioning worsened with increasing severity of depression symptoms (P < .0001) on the basis of PDQ scores. On the basis of responses to the PDQ, in the current study, most impairment was seen in the attention/concentration and planning/organization subscales in severely depressed subjects (12.2 for both) compared with those with no depressive symptoms (4.4 and 3.5, respectively), indicating more cognitive impairment in the severely depressed subjects compared to the subjects with no depression.

In currently employed individuals, self-perceived cognitive dysfunction worsened with increasing severity of depressive symptoms. This association was independent of antidepressant use. The greatest impairment in self-perceived cognition was observed in the planning/organization and attention/concentration subscales.