Almost half of Canadian seniors living in nursing homes and retirement homes are trying to cope with depression, new research finds. And many are suffering without the help they need.

The study, released Thursday by the Canadian Institute for Health Information, found that about one in four (26 per cent) seniors living in a residential care facility, such as a nursing home or long-term care home, had been diagnosed with depression.

A further 18 per cent had symptoms of depression but had not been diagnosed. Many of these residents dealt with persistent anger, tearfulness and repetitive anxiety, yet had not received a diagnosis.

The problem is a serious one becasue, as the researchers note, depression can have serious effects on a senior's medical condition, their emotional state and general quality of life.

Seniors with symptoms of depression are more likely to display aggressive behaviour, or have conflicts with family members or staff. They are also three times more likely to have sleep disturbances, are less self-sufficient than seniors with no symptoms of depression and more likely to have difficulty communicating.

The researchers note there are lots of reasons why seniors living in nursing homes suffer from depression.

"Moving into a care facility is usually quite stressful and often prompted by significant losses in terms of health, degree of independence and/or social supports," Dr. Marie-France Rivard, chair of the Seniors' Advisory Committee of the Mental Health Commission of Canada, explained in a news release.

"This can contribute to the development of a depressive disorder that may include feelings of hopelessness, self-blame and loneliness, possibly accompanied by physical symptoms such as poor sleep, decreased appetite and lack of energy, often leading to social withdrawal."

The researchers also found that residents who showed signs of depression were more likely to have developed a new health condition; others had seen a chronic condition suddenly flare up.

The researchers note that there is a perception that depression is a natural part of aging. That's because a number of factors associated with late-life depression are common among older people, such as: illness, loss of family, friends, social support or independence.

But they note that depression can shorten lives. In studies of the effects of depression on seniors, the odds of dying were 1.5 to 2 times greater in elderly people with depression compared to those without.

Dr. Andrew Wiens, a geriatric psychiatrist at the Royal Ottawa Mental Health Centre, who wasn't involved in the CIHI study, says he's seen the effects of depression on his patients.

"When people are depressed, we know that they are less functional, they have more medical illnesses, they have poor social interaction which makes it difficult for their family members as well," he told CTV.

"When they are treated, and what this study actually does show in that area, that they have fewer medical problems. They are more functional, they're able to socialize with people, they're able to still participate in life."

Antidepressant medications can often help residents with depression. The researchers found that two-thirds of seniors with depression showed no or only mild symptoms on the Depression Rating Scale -- suggesting their symptoms were being effectively managed.

Yet while most psychologists would agree that medications alone are not the answer, very few nursing home residents were receiving psychological therapy, regardless of the presence of symptoms or diagnosis.

Wiens says it's just as important for people at the end of their life to get proper treatment for their depression as it would be for anyone else.

"While sometimes from afar, people will look at these people and say ‘Well, these are older people and they're in a nursing home and they don't contribute as much to society,' for a family member, they're your mother, they're your father, they might be a brother or a sister," he noted.

The study is one of the largest in Canada to look at how common depression is among seniors in care facilities. The study included nearly 50,000 residents age 65 and older across four provinces and one territory (Nova Scotia, Ontario, Manitoba, Saskatchewan and the Yukon).

Nancy White, manager of Home and Continuing Care Development at CIHI, says it's a problem that requires a careful eye.

"As Canada's population ages, and more people could potentially move into residential care, it is important to understand how this population is affected by depression or depression symptoms in order to be able to identify the right treatment options and improve quality of life for these seniors," she said in a news release.