A new study suggests that older adults with a history of depression may live a shorter life than those without the disorder - but past battles with post-traumatic stress disorder may not carry the same risk.
Researchers found that of nearly 36 000 patients in the US Veterans Affairs healthcare system, those who'd been diagnosed with depression had a higher risk of dying over the next two years.
Even with factors such as lifestyle habits and physical health considered, patients with a history of clinical depression were 17 percent more likely to die during the study period than their non-depressed counterparts.
Not true for PTSD
The same was not true, however, of people with a history of post-traumatic stress disorder (PTSD), according to the researchers, led by Dr Leslie S. Kinder of the VA Puget Sound Health Care System in Seattle.
PTSD is a mental health disorder that affects some victims of trauma such as combat, violent crime or serious accidents. Symptoms include flashbacks to the incident, nightmares, sleep problems, irritability and difficulty concentrating - problems similar to those seen in major depression.
What's more, PTSD may predispose people to developing depression.
However, the new findings, published in the journal Psychosomatic Medicine, suggest that depression and PTSD may not have the same effects on long-term mortality.
PTSD risks still substantial
That does not detract from the serious nature of PTSD, however. Other studies of veterans have found that the majority of deaths associated with PTSD are from causes like suicides and accidents, and the risk may be greatest in the first few years after combat, according to Kinder's team.
Their study, in contrast, assessed veterans years, and in some cases decades, after active duty.
The study included 35 715 primary care patients, nearly all men, at seven VA medical centres. Patients with no history of depression or PTSD were 64 years old, on average, while those who had suffered either disorder tended to be somewhat younger.
Overall, only a history of depression was linked to a higher risk of dying during the study period. Patients with a history of both depression and PTSD were at no greater risk when other factors, like physical health and lifestyle habits, were considered.
This latter finding, according to Kinder's team, could mean that veterans with both depression and PTSD received more-intensive mental health treatment - and their long-term health benefited from it.
Cause not clear
The study lacked information on causes of death, and it is not clear why patients with a history of depression had a higher mortality rate, the researchers note.
Past studies, however, have linked depression to a higher risk of death from heart disease. Researchers speculate that direct effects of depression on the nervous system and the heart and vascular system may be to blame.
SOURCE: Psychosomatic Medicine, January 2008. – (Reuters Health)