Research shows that depression is linked to a chemical imbalance in the brain. Depression can also run in families.

Depression that starts later in life is often linked to life events

• The death of a relative or friend
• The loss of a job or retirement
• Loneliness and social isolation from a range of causes (such as limited mobility or hearing loss)
• A hospitalization or placement in a nursing facility
• Chronic illness, disability, or other stresses
• Trauma as a child 

Medical problems that are linked to a higher risk of depression

• Thyroid disorders
• Some vitamin deficiencies
• Alcohol or drug misuse 
• Heart disease or diabetes 
• Side effects from medicines (such as drugs for acne, high blood pressure, sedatives, corticosteroids, and hormones)
• Cancer or other major illnesses
• Long-term pain
• Difficulty getting restful sleep

Often more than one of these problems happens at the same time. 

Last Reviewed and Updated: October 2026 
By: AGS/HiAF Public Education Committee, HealthinAging.org Content Reviewers