But when a risk factor is uncommon among peers – like widowhood or poor health in youth – it can have an outsized effect on depression risk, the study team reports in The American Journal of Geriatric Psychiatry.
“A wide range of risk factors for depression is relevant across the entire life span,” said lead author Roxanne Schaakxs of VU University Medical Center in Amsterdam.
“However, some risk factors expected to be strongly related to depression in certain ages, may actually affect other age groups to a larger extent,” Schaakxs added by email.
Depression is a complex condition and many experts believe that in addition to innate genetic and personality factors, risks like stressful life events, health issues and money problems can contribute to its development, the study team notes.
To see which depression risk factors affect people at various stages of life, and how much of an effect each factor has, the study team analyzed data on more than 2,000 adults participating in two long-term studies of depression and anxiety. Subjects in one study were aged 18 to 65 when they began participating, while participants in the other study were aged 60 to 93 when it started.
At baseline, a total of 1,431 people had major depressive disorder and 784 people had no symptoms or history of the condition.
The research team assessed 19 different risk factors for depression in different age groups, comparing people who had never been depressed with people who were currently depressed.
Most of the risk factors did increase people’s likelihood of being depressed at any age, including low education, recent negative life events, personality traits, reduced social functioning, an unhealthy lifestyle and poor health.
However, five of the risk factors were more strongly related to depression in certain age groups.
For people aged 18 to 39, health factors like overweight or obesity, pain, childhood abuse and chronic disease were strongly associated with depression. For those over 60, low income was a greater risk for depression than in other age groups.
People with risk factors that were “unexpected” based on their age also had a higher depression risk than those in other age groups where the same risk factor was more common, researchers found.
For example, chronic illness was more strongly linked to depression in younger people than older people while low income carried higher depression risk in older people though it was more common among younger people.