Symptoms Not Always Shown
Not everyone whose brain shows the telltale signs of Alzheimer’s disease after death shows symptoms of the disease—memory loss, confusion and emotional outbursts—in life. This raises the possibility some of us may have built up protection in youth that protects the brain in old age.
“Cognitive reserve developed in early life may serve to buffer individuals from Alzheimer’s pathology in later life,” Suzanne Tyas, a University of Waterloo behavioural neuroscientist, reported at the Canadian Association on Gerontology conference in London, Ont., in October.
Hallmarks of Alzheimer’s disease are accumulation of amyloid plaques, a kind of protein, between the neurons in the brain; and twisted fibres, called neurofibrillary tangles, inside brain cells. Until recently it was believed anyone with the plaques and tangles had Alzheimer’s. But the Nun Study showed some nuns whose brains were autopsied after death had the plaques and tangles—but appeared not to be suffering dementia.
The landmark Alzheimer’s study involved 678 School Sisters of Notre Dame born between 1895 and 1916. This group of nuns is a tremendous resource to researchers because the nuns had the same lifestyle, marital and reproductive status, similar behaviours around use of tobacco and alcohol, and the same diet and living conditions since the age of about 20. Other factors responsible for differences in health are more easily spotted, Tyas said. It’s likely a chain of events throughout the life, early mid- and late-life factors contribute to risk of Alzheimer’s.
A study of autobiographies written by about 100 of the nuns when they were about 22 years old, shows “a relationship between early life linguistic ability and late life expression of Alzheimer’s,” said Tyas. Nuns whose writing showed grammatical complexity and greater density of ideas not only lived longer than those with poorer skills, but also were less likely to develop Alzheimer’s.
“Linguistic ability in their 20s was a dramatic predictor of mortality,” said Tyas. Those with higher ability lived about eight years longer.
All participants agreed to have their brains autopsied after death. Of the 180 sisters in total who wrote autobiographies, the brains of 56 showed the plaques and tangles indicative of Alzheimer’s, but only about half showed signs of dementia.
After adjusting for age at death, differences in education and genetic risk factors, there was “a seven-fold increase in likelihood of asymptomatic Alzheimer’s disease” among those with more linguistic ability, and “the top three to five per cent were almost seven times more likely to not show dementia even though their brains showed evidence of the disease.”
Further research may reveal clues to how this ‘cognitive reserve’ works, and strategies to maximize it, she said.
Keeping Blood Vessels Active
Age-related changes to blood vessels have been linked to age-related diminishment in flow of blood to the brain and cognitive impairment.
Researchers at the University of Waterloo measured stiffness of blood vessels in 20 people aged 65 to 91 years with a wide range of cognitive skills, but no dementia, with varying ranges of blood pressure, thickness of blood vessel walls and stiffness of arteries. Then they ranked how well these people did in tests measuring recall of a series of number or letters and response time.
“There was a general decline of blood flow to the brain with age,” Andrew Robertson, a member of the research team, reported to the Canadian Association on Gerontology conference. There was also a consistent relationship between increasing stiffness of blood vessels in relation to the reduction in blood flow to the brain.
This is important because in young people, the blood vessels stretch to accommodate increases in blood pressure. But the stiffer vessels in older people transmit waves of pressure along the vascular network throughout the body. These high pressure waves “have a consequence downstream,” he said, when the high pressure hits the small blood vessels of the brain, heart and kidney where oxygen and nutrient transfer occurs.
What this means to ordinary people is that they might be able to maintain cognitive function and response time if their doctors catch decreases in vascular function early. Changes in flexibility of blood vessels and blood flow may be prevented through “exercise, medications, and possibly through nutrition,” he said.
Five Tips For A Healthy Brain
The Alzheimer Society of Canada has a number of tips on keeping your mind healthy.
- Work your brain. It beefs up brain connections and may help build the cognitive reserve mentioned above. Make a habit of number puzzles or word puzzles. Learn a language or how to play an instrument. Start a new hobby.
- Pal around. Keeping in touch with old friends or making new ones maintains brain function and reduces stress.
- Get cooking. Eat a variety of foods representing a rainbow of colours. Choose whole grain products (brown bread and rice over white, whole grain pastas). Eat seven servings of vegetables a day. Can’t keep count? Have one vegetable and fruit at each meal, and make sure you have one dark green and one orange vegetable each day. Limit salt, alcohol and caffeine.
- Get moving. Walk instead of drive. Find a friend to play a sport with. Take an exercise class or take up yoga. This increases the amount of oxygen circulating to the brain, which is a good thing.
- Bust stress. Meditation, prayer, deep breathing, massage, exercise and play all help us deal better with the everyday pressures of life. See your doctor if you often have the blues, suffer from frequent headaches and fatigue, or find yourself drinking more alcohol or caffeine than usual.
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