Table 1.
Risk factors for major depressive disorder (MDD).
| Risk Factor for MDD | Reference | Timeline | Relative Risk (RR) | Study |
|---|---|---|---|---|
| Female | Male | 10-year follow-up | 2.13, p < 0.001 | [62] |
| Age of onset 55–64 | 45–54 | 10-year follow-up | 0.65, p = 0.040 | [62] |
| Age of onset 65+ | 45–54 | 10-year follow-up | 0.43, p = 0.005 | [62] |
| Underweight | Normal weight | 10-year follow-up | 3.34, p = 0.007 | [62] |
| Family stress (yes) | Family stress (no) | 10-year follow-up | 1.48, p = 0.049 | [62] |
| Traumatic life events (yes) | Traumatic life events (no) | 10-year follow-up | 1.46, p = 0.001 | [62] |
| Chronic disease (with) | Chronic disease (without) | 10-year follow-up | 2.47, p = 0.001 | [62] |
| Higher income inequality | Lower income inequality | Pooled across 12 studies (6 in U.S.) | 1.19, all studies p < 0.05 | [58] |
| Family history of mental health problems (yes) | Family history of mental health problems (no) | 4-year follow-up | 1.92, p < 0.001 | [187] |
| Daily smoking | Non-smokers | 10-year follow-up | 1.72, p = 0.007 | [62] |
| Occasional drinker | Abstainer | 4-year follow-up | 1.56, p < 0.001 | [187] |
| Work-related exposure to violence or threats (yes) | Work-related exposure to violence or threats (no) | Pooled across 4 studies | 1.42, I2 = 0% | [188] |
Relative risk (RR, the cumulative incidence with respect to the specified reference group) for established depression risk factors. The timeline column indicates the length of time that elapsed between the initial study and the follow-up study used to calculate the RR. For the two meta-analyses, the timeline column indicates the number of studies pooled to calculate the mean RR across studies. P-values or I2 are indicated next to each RR. I2 is a measure of consistency of results between studies used in meta-analyses [189].