TORONTO - Perhaps it begins with recurring forgetfulness, a struggle to find words or maybe needing repeated reminders about an upcoming event. Or it may be that some everyday tasks, performed over a lifetime with unthinking ease, suddenly seem overwhelming.

Such memory missteps could, of course, be signs of Alzheimer's disease. But specialists say there are many forms of age-related dementia and cognitive impairment, and nailing down the likely cause can ensure early and appropriate treatment.

"It is important to get a specific diagnosis because some medications work for one dementia and not another," says Dr. Tiffany Chow, a behavioural neurologist in the memory clinic at Baycrest in Toronto.

For some, memory and thinking problems could result from what's called mild cognitive impairment, or MCI, a sort of mid-step between the waning mental clarity that's normal as we age and the more exacerbated decline of dementia.

The condition is common in seniors, affecting about one in 10 of those aged 65 to 74, then rising to more than 60 per cent of those over 85.

Hockey legend Gordie Howe appears be one of them.

His son Murray, a doctor who specializes in radiology, says his father's symptoms don't fit either Alzheimer's or Pick's disease, a rare form of dementia that led to the death of his mother Colleen at 76.

Howe, now 83 and still active, is doing his bit to raise awareness. The Gordie and Colleen Howe Fund for Alzheimer's has raised more than $16 million.

While the onset of mild cognitive impairment can be frightening, Chow says the condition isn't necessarily the first step on the road to Alzheimer's or any other form of dementia. Some people will progress to that stage, but others never get worse and a few even improve.

Vascular dementia affects about 20 per cent of Canadians diagnosed with dementia, making it the second most common form. The disorder is caused by the death of brain cells, which have been starved of oxygen-rich blood as a result of high blood pressure, heart disease, high cholesterol or diabetes. A succession of mini-strokes can also lead to vascular dementia.

But with early treatment — typically drugs that control these underlying disorders, plus changes to diet and exercise — the progression of vascular dementia can be significantly delayed or even halted altogether.

Certainly, Alzheimer's is the most common form, accounting for almost two-thirds of the 500,000 cases of dementia among Canadians — a figure that's expected to double to 1.1 million within a generation.

The disease, first described in 1906 by German physician Alois Alzheimer, arises from destruction of neurons linked to deposits, called beta-amyloid plaques, and tangled bundles of fibres that form in the brain. Starting in the hippocampus, a key structure involved in laying down memory, cell death eventually spreads to other parts of the brain and breaks down connections between neurons.

"It's just a neurodegenerative process," explains Dr. Mary Tierney, director of the Geriatric Research Unit at Sunnybrook Health Sciences Centre in Toronto, whose studies show that brain changes likely begin a decade before symptoms first appear.

"Whatever kick-started it in the first place, that whole cell loss, is just continuing. And that sort of relentless continuation is what we're really trying to stall."

Drugs to slow the progression of the disease and tamp down symptoms include cholinesterase inhibitors, which boost a chemical messenger called acetylcholine that's needed for memory, thought and judgment.

"They've been shown to help a bit with attention, recent memory, but they seem also to have an effect on progression of a decline in autonomy ... the ability to handle daily tasks," says Dr. Serge Gauthier, a neurologist at the McGill Centre for Studies in Aging in Montreal.

"And there are some behavioural effects, so there's less apathy, or lack of interest," he says of the drug class often prescribed for mild to moderate Alzheimer's.

A second medication, memantine, works on a different neurotransmitter and is most effective in the later stages of the disease, in particular reducing agitation and aggressivity as well as improving word recall and allowing a patient to maintain physical functions longer.

Combining the drugs can keep a person with Alzheimer's out of long-term care for many months, even up to a year, Gauthier says.

But there is no cure for Alzheimer's, and pharmaceutical companies are scrambling to come up with compounds that could reverse or halt the relentless brain damage.

"It's such a horrible disease, but nothing is on the horizon yet," says Tierney.

As the birthdays add up, so does the risk of developing one kind of dementia or another.

"So as you get older more of your peers will have mild cognitive impairment and more of your peers will have dementia," says Chow. Between 60 and 65, up to five per cent will have Alzheimer's; by age 70 to 75, maybe 20 per cent will be affected. "And by the time you're in your late 80s, at least a third of the people around you would have dementia."

Among older seniors, those over 75, cognitive decline often results from a mixed bag of conditions — perhaps Alzheimer's, vascular and Parkinson's-related dementia, says Gauthier.

"It's not always black and white."

Still, there is no getting around the reality that Alzheimer's and some other forms of dementia are ultimately fatal.

For those affected by dementia, reactions to the diagnosis are as varied as the individuals themselves, says Marija Padjen, chief program officer at the Alzheimer Society of Toronto.

"Because of the very nature of the disease, some individuals will have much more awareness than others," she says. "So, for example, Mrs. Smith may be diagnosed with the disease, but she may have zero awareness of the fact that these symptoms are happening, that she's having memory lapses, etcetera, because the part of her brain that would allow for her to have a realization is affected."

That lack of insight, a condition known as anosognosia, can be tough on the patient's family, Gauthier points out.

"They're the ones who don't want to go to see the doctor, they're brought in by the family, (saying). 'There's nothing wrong with me. I don't need any medicine. I can drive.'

"But in a way it's less stressful for them."

Others have some awareness, while there are those few who have full insight, and that knowledge can persist as the disease slowly but inexorably chips away at memory, personality and the person's ability to function. "And they're really miserable, with a lot of anxiety," he says.

Common reactions to a dementia diagnosis are grief over the loss of self and control over one's life, adds Padjen. "There's a lot of fear of the unknown — and fear of the known. They may have had a family member diagnosed and know what's in front of them and it can be terrifying."

For family members, and especially those who become full-time caregivers, the diagnosis can be an emotional blow.

"For a lot of people, the grief begins with the diagnosis," says Padjen. "There's so many losses associated with the illness that they begin to g
rieve that individual and the loss of that relationship and the loss of the life that they had together."

"There's a term they use," adds Gauthier, "the unending funeral."

Tierney suggests family members will find it easier to cope if they try to remain rooted in the present, instead of fearing what the future will bring for their loved one with dementia.

"Focus on the person now and what they have."

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Online:

Alzheimer Society of Canada: http://www.alzheimer.ca

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Cognitive impairment, dementia common in seniors, proper diagnosis key to treatment