Prevention of dementia
Prevention of dementia is the attempt to avoid developing dementia. Although no cure for dementia is available, there are ways of decreasing the risk of developing dementia, including both lifestyle changes and medication.
"Use it or lose it" might be applied to the brain when it comes to dementia. Intellectual activities help keep the mind in shape in later years. Activities such as reading, playing cards and board games and playing a musical instrument can postpone the onset and slow the progression of both Alzheimer's and vascular dementia. The risk decrease is proportional to frequency of activity, with slower cognitive decline being associated with both late-life and early-life increased cognitive activity.
Apart from spare time activities, a mentally demanding job may prevent dementia, especially during the thirties, forties and fifties.
Since vascular dementia is the second most common form of dementia (after Alzheimer's disease), reducing the risk of cerebrovascular disease also reduces the risk of dementia. Thus, physical exercise, having good blood cholesterol, healthy body weight and blood pressure lowers the risk of developing dementia. An active lifestyle can almost halve the risk compared to a sedentary one.
The effect of physical activity is not limited to vascular effects. Physical activity can give rise to new neurons in the brain, as well as releasing a substance that can protect them. The protein known as brain-derived neurotropic factor (BDNF) is known to be important in the development, survival and plasticity of neurons. Regular exercise can boost BDNF levels by 2-3 times.
Obesity increases the risk of any dementia and Alzheimer's disease in particular. The effect of alcohol on the risk of dementia is a J curve: high alcohol consumption increases the risk of dementia while low alcohol consumption may be protective. However, low alcohol consumption may not protect against vascular dementia and overall cognitive decline. Moderate alcohol consumption can possibly reduce the risk of vascular disease and dementia because it can increase blood levels of HDL cholesterol and weakens blood-clotting agents such as fibrinogen, which offers some protection against heart attacks and small subclinical strokes that together can ultimately damage the brain.
The effects of omega-3 fatty acid in the prevention of dementia is uncertain. Vegetables and nuts may be of benefit, because of their high content of polyunsaturated fats. Non-fish meat, on the other hand, increases the risk of Alzheimer's, because of its high content of saturated fat. However, consumption of fish should be limited due to concerns over mercury poisoning, which could exacerbate the symptoms of dementia.
Niacin (vitamin B3) is also believed to prevent dementia as research shows those who have the highest levels of niacin in their blood, are believed to have the lowest risk of developing dementia or having cognitive decline. Niacin is involved with DNA synthesis and repair and also neural cell signaling, it improves circulation and reduces cholesterol levels. In order for niacin to have a positive effect on the brain, it is recommended that patients have 100 to 300 mg per day.
There is evidence for an association between cognitive decline, homocysteine (Hcy) status, and vitamin B status relating especially to B12 and also to vitamins B6 and B9. In particular, deficiency of vitamin B12 and/or of folate can cause an increase in Hcy plasma levels, which in turn leads to toxic effects on the vascular and nervous systems.
More than nine hours of sleep per day (including daytime napping) may be associated with an increased risk of dementia.
However, a study failed to demonstrate a link between high blood pressure and developing dementia. The study, published in the Lancet Neurology journal July 2008, found that blood pressure lowering medication did not reduce the incidence of dementia to a statistically significant degree. A prospective meta-analysis of the data from this study with other studies suggested that further research might be warranted.
Besides, Rosiglitazone (Avandia) improves memory and thinking ability for people with mild Alzheimer's disease. The mechanism of the effect may be the ability of the drug to reduce insulin resistance. Thus, less insulin needs to be released to achieve its metabolic effects. Insulin in the bloodstream is a trigger of amyloid beta-production, so decreased insulin levels decrease the level of amyloid beta. This leads to less formation of amyloid plaques seen in Alzheimer's disease.
Estrogen may also help in the prevention of dementia but cannot help when dementia is already present and when cognitive function is already impaired. It increases cerebral blood flow and is an anti-inflammatory agent, enhancing activity at the neuronal synapses in the brain. It may also help to increase brain activation in regions that are affected by dementia which is mainly the hippocampus region. Recent evidence on the effects of estrogen do not allow for an unambiguous recommendation for estrogen supplementation and they indicate that the timing of estrogen supplementation may be important, with early postmenopausal use being preferable over its use later in life.
Non-steroidal anti-inflammatory drugs (NSAIDs) can decrease the risk of developing Alzheimer's and Parkinson's diseases. The length of time needed to prevent dementia varies, but in most studies it is usually between 2 and 10 years. Research has also shown that it must be used in clinically relevant dosages and that so called "baby aspirin" doses are ineffective at preventing and treating dementia.
Alzheimer's disease causes inflammation in the neurons by its deposits of amyloid beta peptides and neurofibrillary tangles. These deposits irritate the body by causing a release of e.g. cytokines and acute phase proteins, leading to inflammation. When these substances accumulate over years they contribute to the effects of Alzheimer's. NSAIDs inhibit the formation of such inflammatory substances, and prevent the deteriorating effects.
There is as yet no vaccine against dementia. Such a vaccine could activate the body's own immune system to combat the beta amyloid plaques in Alzheimer's disease. One problem to overcome is overreaction from the immune system, leading to encephalitis.
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