Depression significantly affected the lifestyles of about one-fifth of participants in a study focusing on women 65 and older, researchers say.

The records of more than 7,200 women located at four clinic sites from 1988 to 2009 were examined. Severe depression or increasing symptoms in the study subjects were associated with unhealthy old age, high rates of disability, comorbid physical illness, and unhealthy lifestyles, the research shows.

“These associations support the need for intervention and prevention strategies to reduce depressive symptoms into the oldest-old years,” wrote the authors, who were led by Amy L. Byers, Ph.D., MPH, University of California, San Francisco, Veterans Affairs Medical Clinic.

The ongoing prospective cohort study showed women with severe depression were more likely to have diabetes, obesity, myocardial infarction, and physical disabilities. In addition, they were more likely to smoke and to be physically inactive and socially isolated than women with minor depressive symptoms.

They also noted that more long-term investigations of depressive symptoms in this 80-and-older age group are needed since it is the fastest growing age cohort in the United States.

“Given the increased life expectancy, the health and economic costs of depression, and the projected expansion of the older populations, the potential public health burdens of late-life depressive disorders implicated by our study are concerning,” the researchers noted.

The goal of the study was to characterize the natural course of depressive symptoms among “young” older women by providing follow-up into the ninth and tenth decades of life, a period that has been little studied.

Four types of symptoms were identified: minimal depressive symptoms (27.8%), persistently low depressive symptoms (54.0%), increasing depressive symptoms (14.8%), and persistently high depressive symptoms (3.4%).

Antidepressant use among study subjects was low for all groups but increased with severity. The drugs’ use was only 7.1% among women with persistently high depressive symptoms.

The study was featured in the October issue of Archives of General Psychiatry