Major depression affects approximately 1-2% of older adults, but as many as 20% may experience symptoms of depression.

Lisa C. Barry, PhD, MPH, Yale University School of Medicine, New Haven, evaluated 754 individuals all over the age of 70. The study began in 1998, with follow-up assessments done every 18 months. Over the course of the study:

• 35% of participants were depressed at some point,
•  of those 18% remained depressed during 2 consecutive time periods,
• 11% for 3 time periods,
• 6% for 4 time periods,
• 5% for all 5 time periods.

More women than men were depressed at each 18-month follow-up time period. Women were more likely than men to experience depression at subsequent time points.

The finding suggest that depression is more persistent in older women than older men. This surprised the researchers because women are more likely to receive medications or other treatment for depression. In addition, nearly 40% of the depressed participants in the study were depressed during at least 2 consecutive time periods.

Researchers feel their study highlights the need to initiate and potentially maintain antidepressant treatment after resolution of the initial depressive episode.