101 Facts About Ageing #36: Prevalence Of Depression In Different Age Groups

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

Depression is more common among older adults when considered worldwide and when all forms of depression are included. According to the Institute for Health Metrics and Evaluation (IHME), an estimated 3.6% of the total global population were affected in 2017, compared with over 6% of adults aged 50 or more. At all ages, females are more likely to be diagnosed with depression than males.

It’s important to realise that depression is subcategorised into multiple disorders that are distributed differently throughout different age groups. Furthermore, the measured incidence of depression varies significantly between different countries. According to the Substance Abuse and Mental Health Service Administration (SAMHSA), in the United states in 2017, the incidence of major depressive episodes among 18-25 year-olds was over twice as high as amongst those aged 50 or older. However, we know that older adults are less likely to report symptoms of depression than younger individuals. Some symptoms (such as loss of energy or appetite) are common to both depression and ageing and may therefore dismissed as ‘just part of growing old’, leading to an under-recognition of depression among the elderly.

Depression has many potential causes. In young people, most frequent causes of depression are not directly linked to the ageing process itself. They include stressful life events such as loss, breakups, academic and career failures, financial difficulties. Increased alcohol consumption also increases the risk and severity of depression.

Among the elderly on the other hand, many contributors to depression are related to the ageing process itself. They include declining physical health and reduced ability to participate in fulfilling activities, discrimination based on age, lack of sleep, lack of physical exercise and the stress of living with chronic medical conditions. Depression has also been proposed as both a consequence and a driver of dementia and cognitive decline, though the link between the two is complex and not fully understood. Studies suggest that depression is experienced by around 30% of vascular dementia and Alzheimer’s patients, and by over 40% of those with Parkinson’s and Huntington’s disease.