It is not well known whether the association between common mental disorders and low socioeconomic status vary with symptom severity, type of socioeconomic indicator or gender.

To study the association between socioeconomic status and risk for different severity levels of psychological distress as well as depression.

A population-based survey was conducted among a random sample of Stockholm County residents aged 18–84 years in 2002, and respondents were reassessed via a follow-up questionnaire in 2007. Participants in both surveys (n = 23 794) were categorized according to socioeconomic status at baseline and followed up for onset of psychological distress (according to the twelve-item general health questionnaire) and depression (according to health data registers).

Occupational class had little impact on risk for distress regardless of severity or gender, but was strongly associated with onset of depression - albeit only in men (ORs being 3.0 [95% CI 1.5–5.9] in men and 1.1 [95% CI (0.7–1.7]) in women, comparing unskilled manual workers with higher non-manual workers). Income was associated with risk for onset of all outcomes and the association grew stronger with symptom severity. High household income was particularly protective of depression in women. Education was unrelated to either outcome in men and women overall.

While psychological distress appears to occur at a similar rate regardless of socioeconomic position, risks for severe distress and especially clinically overt depression are markedly linked with occupational class in men and with family income in women. The socioeconomic gradient in common mental disorders increases with symptom severity.