(Reuters Health) - Elderly people with major depressive disorder may be more likely to suffer severe and persistent symptoms than younger adults with the same mental health diagnosis, a Dutch study suggests.

Researchers examined data on 1,042 adults with major depressive disorder who ranged in age from 18 to 88. The researchers studied how depression developed over time by comparing symptoms at the start of the study to symptoms two years later.

Compared to participants ages 18 to 29, people aged 70 and older were two to three times more likely to still have a diagnosis of major depressive disorder after two years, and to have had symptoms during most of that period, the study found.

Elderly people also took longer to achieve remission or to experience improvements in the severity of their depression.

One theory for why this might be the case is that elderly people are more likely to have risk factors for depression like multiple chronic illnesses, loneliness or unhealthy lifestyles. But depression had an outsize impact on elderly people even after researchers accounted for these factors, said senior study author Brenda Penninx of VU University Medical Center in Amsterdam.

It’s also possible that the aging brain has less plasticity, or ability to rebound from mental illness, due to underlying inflammation or metabolic processes in the body that are different than what’s typical earlier in life, Penninx said by email.

Prevention, as well as early diagnosis and treatment, are essential, Penninx said.

“Obviously preventing is better than treating,” Penninx added.

“Everything that works (e.g. healthy lifestyle, social activities, taking care of one’s health as much as possible) in preventing depression is good,” Penninx advised. “In addition, if a depression occurs, seeking adequate treatment is important because there is - especially among older adults - quite some under-recognition of depression.”

Almost one in five adults will experience a bout of major depression at least once in their lifetime, but the course of these episodes can be highly variable, the study team notes in The Lancet Psychiatry.

Major depression affects people of all ages, but the risk is highest between ages 45 and 65, said Tze Pin Ng of the National University of Singapore, author of an accompanying editorial.

Although the risk of developing major depression is lower in older people, partly because of their better ability to cope with stress and emotional regulation, elderly adults who do develop depression tend to have worse cases than their younger counterparts, Ng told Reuters Health by email.

“The current study goes further than other studies so far in establishing the poorer clinical course and worse treatment outcomes of depression in late life,” Ng said.

Particularly when people develop depression for the first time after 65, they’re more likely to have damage to small blood vessels in the brain and greater degrees of cognitive impairment than might have been the case earlier in life, Ng added.

Risk factors for heart disease and stroke like obesity, high blood sugar and high cholesterol can also cause damage to the blood vessels in the brain, Ng said.

While more research is needed to determine the exactly how age may influence the course of depression, elderly people can still take steps to protect themselves, Ng said.

“It is reasonable to suggest that older people can help themselves to reduce their risk of becoming depressed or their severity of depression by giving attention to adequate levels of physical and social activities and healthy dietary habits to reduce their metabolic and vascular risks of developing heart disease, dementia and depression all at the same time,” Ng advised.

SOURCE: bit.ly/2KeF3Bh and bit.ly/2tzRldk The Lancet Psychiatry, online June 7, 2018.