3. Depression is pain
Literally. Depression has a number of physical symptoms such as low energy level and appetite suppression. These signs can also indicate serious medical problems such as heart disease, according to Bobo. "It's not just a psychological experience," he says. "Often, the physical symptoms are the ones that come to medical attention first even before feelings of morbid sadness."
Research published in the journal Health and Quality of Life Outcomes found that half of women diagnosed with depression also experienced physical pain; the more severe the pain, the more severe their depression.
To complicate matters, depression can be difficult to diagnose in people who experience physical, not emotional, symptoms. If depression is left untreated — which can happen if doctors are working to identify the cause of the aches and pains and not asking about possible emotional issues — Bobo warns, "It can worsen treatment outcomes and make recovery more difficult to achieve."
4. Hormones may play a role
Women are diagnosed with depression twice as often as men, possibly because they're more at risk because of hormonal changes, including menopause. However, testosterone may also play a role in men's depression.
According to research published in the journal Drugs and Aging, the age-related decline in testosterone levels could lead to an increase in depressive symptoms in men. But there may be some potential good news: In 2011, researchers at Florida State University conducted four studies in which male rats were injected with testosterone. The hormone had the same effect as antidepressant medications, reversing the impact of depressive symptoms.
5. Depression increases the risk of stroke
Depression was linked to a more than twofold increase in stroke risk for women between the ages of 47 and 52, according to a study published in Stroke, the journal of the American Heart Association.
"It's unclear why depression is so strongly linked to stroke … but it is thought that the body's inflammatory processes and their effects on blood vessels may play a part," says Caroline A. Jackson, Ph.D., researcher and epidemiologist in the School of Population Health at the University of Queensland.
It's part of a growing body of research linking mental health to physical health, says Jackson. She encourages older adults with depression to seek medical help and maintain or adopt a healthy lifestyle to minimize their stroke risk.
Next page: Men, depression and suicide. »