When it comes to brain function, several long-held beliefs have now been debunked.
THERE are no certainties in life, except for ageing, which occurs from the day of birth. Although there is a neverending search for eternal youth, the fact remains that as the body ages, so does the brain.
Knowledge of the brain, which is the most vital of human organs, has been limited, until recently. The increase in life spans and technological advances, like magnetic resonance imaging (MRI) and positron emission tomography (PET) scans, have accelerated the understanding of the processes of brain function. This has been driven by the search to preserve brain function for as long as is possible.
The brain, which contains billions of cells (neurones), is responsible for all physical life support functions like breathing and heart beat, as well as mental functions like thinking, memory and creativity. The brain cells communicate with other cells in the nervous system through a complicated system involving electrical impulses and various chemicals (neurotransmitters) at high speeds.
Until about a decade ago, it was thought that the brain neurones were gradually lost from birth. It is now evident that if a person has no specific disease that causes neuronal loss, most neurones, if not all, will remain functional until a person dies.
The brain changes with age. Its weight decreases by 5% to 10% between 20 and 90 years. The grooves on its surface widen and the swellings on the surface become smaller. Some neurones shrink. The ability to rearrange connections between the neurones is reduced (loss of plasticity) and there is formation of clusters of damaged or dying neurones (senile plaques).
There is also an increase of decayed parts of the branch-like denticles which extend from the neurones (neurofibriallary tangles). Like other body parts, the brain can also be damaged by free radicals.
The changes are subtle and affect certain areas of the brain more than others. The areas at increased risk are those involved in learning, memory and complex mental activities.
Apart from the physical changes, a surprising finding is data that suggests cognitive decline like age-related memory loss, is not due to neurone loss, as previously thought. The current thinking is that these changes are related to complex chemical interactions in the brain that occur over time. The age-related loss of dopamine, a brain chemical associated with pleasure and reward, slows down the metabolism in the brain regions related to cognition.
These changes affect individuals differently. Some senior citizens notice they may take a longer time to perform complex daily tasks, but they do them as well as in their younger days. However, others find it difficult to perform such tasks.
The factors affecting the different rates have still to be elucidated. It is believed that genetics play an important role.
Recent findings have revealed that lifestyle factors influence the rate of changes in the brain with age. A healthy lifestyle has been found to be useful in maintaining brain health with increasing age.
Exercise the brain
The adage, “Use it if you don’t want to lose it”, is very relevant to brain function. By repeatedly using the brain neurones’ connectivity patterns, the synapses between them are probably made broader and their connections stronger. It would be tempting to make a comparison with the rest of the body, inactivity of which leads to atrophy and wasting.
There are several ways to challenge the brain to keep it in shape. New activities are helpful as they can lead to the creation of new brain pathways to serve as alternatives in the event some neurones are damaged. This could be games, learning of new skills or volunteering.
Physical activity provides protection against loss of brain function. Exercise increases cardiac output, and consequently, blood flow to the brain, and it may enhance neuronal growth. Studies have reported that rapid walking for about 45 minutes thrice weekly improves significantly the age-related decline in cognitive function.
One does not have to do strenuous exercise immediately but one can gradually increase the level of physical activity in daily life, eg walking, taking the stairs instead of the lift, swimming. If strenuous activities are undertaken, personal protective equipment may be necessary as head injuries are a risk factor for memory problems.
A healthy well-balanced diet goes a long way in preventing chronic diseases like high blood pressure and diabetes that affect brain function. Even if one has these conditions, a healthy diet helps in keeping them under control. It is often forgotten that diabetes can be controlled by diet alone.
It is important to remember that a person’s energy requirements decrease with increasing age because of a reduction in the body’s metabolic rate. As such, body weight should be kept under control.
A well-balanced diet should include proteins that supply the brain with amino acids (which are the building blocks of proteins), unsaturated fats (which are an essential constituent of neuronal membranes), glucose to provide energy for neuronal function, as well as plenty of fruits and vegetables that provide antioxidants to protect the neurones.
As the brain does not have much storage capacity for glucose, it has to receive a steady supply from the blood vessels. Foods with a low or medium glycaemic index, eg brown rice, oats and whole grain bread, which provide a steady release of glucose into the blood, are preferable.
Smoking causes numerous health problems. There are more than 4,000 substances released in tobacco smoke. Smoking affects memory, with smokers having twice the risk of Alzheimer’s disease. Smoking cessation reduces the risk of dementia and that of heart attack and lung disease, both of which have negative impacts on brain function.
During stress situations, the body produces cortisol, a hormone which, in small amounts, improves memory. However, when produced in larger amounts, especially over a long period of time, it leads to neuronal injury in the hippocampus, which is a factor in memory loss.
The risk of anxiety and depression is increased with stress. Both conditions can affect memory.
Should stress be an issue, there are measures that can be taken to reduce and manage it.
Moderate alcohol consumption has beneficial effects on heart function, with consequent impact on brain function. It can help prevent memory loss, the mechanism of which is not well elucidated. It is believed that alcohol decreases the likelihood of blood clot formation and consequent tissue damage.
Teetotalers are not advised to start taking alcohol for this benefit because there are other ways of obtaining it.
Excess alcohol consumption, especially if prolonged, can result in brain damage. The health authorities in most countries advise that healthy individuals should not drink more than two standard drinks per day.
Senior citizens are more prone to harm from alcohol-related disease and interactions between alcohol and medicines. If one is taking medicines, it is advisable to check with the doctor or pharmacist whether there is any interaction between the medicines and alcohol.
Regular health checks
Regular health checks help in the diagnosis of diabetes, high blood pressure and heart disease, all of which increase the likelihood of memory loss, especially if untreated or inadequately treated. Studies have suggested that high blood pressure accelerates normal brain shrinkage.
Treatments for these conditions are easily available and accessible, but the challenge is patient compliance to treatment.
It is known that the brains of some boxers have changes similar to that of Alzheimer’s disease, except that it occurs at a younger age. There are also reports of decline in cognitive function of former footballers in relation to the frequency of their heading the ball. It is probable that the avoidance of head trauma will decrease the likelihood of premature brain ageing.
Various products are marketed as anti-ageing compounds. In order that readers get an accurate picture, refer to the Cochrane Database of Systemic Reviews, a global collaborative effort of doctors and scientists that provide independent high-quality evidence for healthcare decision making.
Gingko biloba has been used in traditional medicine for its anti-ageing effects. Its impact on those with dementia or cognitive impairment has been stated in the Cochrane Review: “Of the four most recent trials to report results, three found no difference between ginkgo biloba and placebo, and one reported very large treatment effects in favour of ginkgo biloba. Ginkgo biloba appears to be safe, with no excess side effects compared with placebo. Many of the early trials used unsatisfactory methods, were small, and publication bias cannot be excluded. The evidence that ginkgo biloba has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable.” (Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews. 11, 2010) However, there is no evidence that gingko biloba slows down mental decline in healthy individuals.
DHEA has also been promoted as an anti-ageing supplement. The conclusions from the Cochrane Review were: “The data offer no support at present for an improvement in memory or other aspects of cognitive function following DHEA treatment in normal older people.” (Dehydroepiandrosterone (DHEA) supplementation for cognitive function. Cochrane Database of Systematic Reviews. 1, 2009)
Similar conclusions were found with folic acid. “The small number of studies which have been done provide no consistent evidence either way that folic acid, with or without vitamin B12, has a beneficial effect on cognitive function of unselected healthy or cognitively impaired older people.” (Folic acid with or without vitamin B12 for the prevention and treatment of healthy elderly and demented people. Cochrane Database of Systematic Reviews. 1, 2009)
In short, the jury on the role of supplements in brain health is still out.
It would be advisable to discuss with the doctor before commencing a supplement. This is to ensure that it is appropriate and that it does not interact with medicines that are being taken.
The brain is one of the frontiers of medical research. There is optimism that better understanding and treatment of brain ageing is on the horizon. What is already known is that cognitive decline is largely preventable with a healthy lifestyle.
■ Source: Dr Milton Lum