Alzheimer’s is becoming an increasing problem as Canada’s population continues to age. Alzheimer’s, the most common form of dementia among the elderly, is an irreversible disease of the brain that increases in severity over time.
Early signs include memory loss and a decline in cognition. The mild stage of Alzheimer’s takes the form of memory loss, worsening judgment, slower performance of daily tasks, and changes in personality and mood. Moderate Alzheimer’s is characterized by damage to the parts of the brain that control language, reasoning, conscious thought, and sensory processing. Patients have difficulties recognizing loved ones, are unable to learn new things or cope with new situations, can’t perform tasks involving multiple steps, and have hallucinations, delusions, paranoia, and impulsive behaviour. In severe Alzheimer’s, the whole brain is affected – sufferers are unable to communicate, become completely dependent on others, and their bodies start to shut down.
Scientists suspect that damage to the brain associated with the disease appears about 10 years before patients start experiencing symptoms. This damage includes abnormal protein deposits in the brain (amyloid plaques) and tangles of a tau protein (neurofibrillary tangles). This makes the nerve cells in the brain (neurons) work less effectively. The neurons eventually lose the ability to communicate with each other, ultimately dying. The loss of nerve cells spreads to the hippocampus, the part of the brain responsible for forming memories and one of the first parts of the brain to be affected by Alzheimer’s. As nerve cells die, the parts of the brain that are affected shrink. The body starts to shut down when the whole brain becomes affected.
Some people are more prone to developing Alzheimer’s disease than others. It is likely that a combination of genetic, environmental, and lifestyle factors lead to its onset. Older people with mild cognitive impairment are at increased risk. Part of the cause of Alzheimer’s could be associated with changes to the brain during the process of aging, such as the shrinking of some parts of the brain, inflammation, the action of unstable molecules (free radicals) on the cells, and problems with mitochondria (small bodies inside cells that make energy). According to the Alzheimer’s Association, the likelihood of getting Alzheimer’s doubles every 5 years after a person turns 65. By 80, it is at 50 per cent.
Early-onset Alzheimer’s, which affects people from 30 to 60 years old and is responsible for less than 5 per cent of cases, is generally believed to be caused by genetics. The early-onset form of the disease is mainly associated with the inheritance of one of three genes from parents (APP, PS-1, PS-2). Some studies have linked the common, late-onset form of Alzheimer’s with the APOE ε4 gene.
Other risk factors may include conditions associated with the metabolism and the cardiovascular system, inflammatory conditions, unhealthy diet, obesity, lack of physical activity, clinical depression, stress, smoking, drug and alcohol abuse, lack of social contact, and not engaging in activities that stimulate the mind. There is also a possibility that copper, zinc, and iron could play a role in the development of plaque deposits in the brain. Recent studies show that aluminum, which was thought to cause Alzheimer’s in the 60s and 70s, has no role.
According to Rising Tide – The Impact of Dementia on Canadian Society, a 2010 report by the Alzheimer Society of Canada, most scientists agree that the brain must maintain a balance between negative effects on the brain and self-repair mechanisms, which allow for a balance between the creation and disposal of metabolic products. A change to the balance and the resulting accumulation of high levels of metabolic products would be toxic to the brain and lead to Alzheimer’s. This is brought about by conditions of oxidative stress, which could be caused by other diseases, some drugs, and internal stress due to threats to a person’s health.
Rising Tide states that 500,000 Canadians suffered from Alzheimer’s or related dementia in 2012 and this number is supposed to more than double within a generation. About 1 in 11 Canadians over 65 have Alzheimer’s or related dementia. Women make up almost three quarters of Alzheimer’s patients. By 2015, the organization predicts that 50 per cent more Canadians and families would have to cope with problems associated with Alzheimer’s and related dementia. Alzheimer’s will become a more pressing issue as the population continues to age and becomes more vulnerable towards developing the disease.
This is the first in a series on Alzheimer’s and dementia that will appear in The Interim.