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Every system in the body changes inevitably as we age. These changes also include the components of the nervous system. Brain ageing can be considered to be unavoidable to some extent, but not uniform. Ageing affects every brain differently.
Throughout one's lifetime, the brain changes more than any other part of the body. From the time the brain begins its development (during the third week of gestation) to old age, the complex structures and functions of the brain keep changing.
Read on to know how the brain changes over time and also the steps that can be taken to reduce the rate of this decline.
The Human Brain
The human brain (at about 1.3 kg in weight) possesses around 100 billion neurons that are interconnected via trillions of synapses . This in itself exemplifies the magnificent engineering that our brain has covered.
During the first few years of one's life (during the infant and toddler years), the brain forms about one million neural connections almost every second. The last areas of the brain to mature are the frontal lobes - the area that manages the executive functions such as working memory, planning and impulse control. In some cases, this is not fully developed until one reaches 35 years of age.
How Brain Cells Work
Neurons or the nerve cells are responsible for processing and sending information throughout the brain. These cells are also responsible for sending information from the brain to the muscles and organs of the body.
The following three processes are important for the neurons to function and survive :
• Communication: An electrical charge is generated whenever a neuron receives signals from other neurons. This electrical charge travels to the synapse (a small gap where neurotransmitters are released and moved to another neuron).
• Metabolism: This process includes all the chemical reactions that occur in a cell for its functionality and survival. For these reactions to occur, oxygen and glucose are required. The oxygen and glucose are obtained from the blood flowing to the brain.
• Remodelling, repairing and regeneration: Neurons need to constantly keep repairing and maintaining themselves. There are regions of the brain that also continue to make new neurons. Glial cells (other types of brain cells) play a major role in supporting neurons.
The brain also has a huge network of blood vessels. The brain receives about 20 per cent of the body's blood supply.
Symptoms Of Ageing Brain
As one ages, the brain (along with other systems of the body) begins to gradually decline. Memory slips are highly common in the elderly (however, even young adults experience minor memory slips at times). When it happens in the elderly, then it is usually associated with dementia or Alzheimer's disease.
However, one should know that Alzheimer's and other dementias are not part of the normal ageing process.
The following are the common memory changes or the symptoms that one can associate with normal ageing of the brain :
• Multitasking ability: Slowed memory processing can make planning parallel tasks quite difficult.
• Difficulty in learning new things: Retaining and committing new information to memory can take longer than usual.
• Remembering appointments: Unless the memory is jogged, it could be difficult remembering appointments that are safe in the memory storage.
• Recalling names and numbers: Memory of names and numbers is associated with something known as the strategic memory. This seems to decline as one ages.
Some studies show that about one-third of old people struggle with declarative memory (memories of events and facts that have been stored and can be retrieved when required)  . Other studies have indicated that about one-fifth of 70 plus people are able to perform cognitive tests just like any 20-year-old would do.
How The Structure Of The Brain Changes With Age
The following are some of the structural changes that occur when the brain ages :
• Cortical density: Declining synaptic connections lead to the thinning of the outer-ridged surface of the brain. When there are fewer connections, it can cause slower cognitive processing.
• Brain mass: The areas involved in high cognitive function and encoding new memories (frontal lobe and hippocampus) begin to shrink. This begins to happen at about 60 years of age.
• Neurotransmitter systems: According to research, with ageing, the brain begins to generate less chemical messengers. There is a decline in acetylcholine, dopamine, serotonin and norepinephrine activity. This attributes towards the decline in cognition and memory. This also leads to increased depression.
• White matter: Myelinated nerve fibres are present in the white matter. These nerve fibres are bundled into tracts and are responsible for carrying nerve signals between brain cells. With age, myelin shrinks. This leads to slower processing and reduction in cognitive functionality.
Ways To Delay Effects Of Ageing On The Brain
In spite of ageing, one can still continue to be mentally sharp. For this to happen, one needs to work on the mental muscles each and every day. Activities that involve concentration can help in strengthening the mind .
1. Mental stimulation
It is suggested that after 40, one should take up a new course, such as learning a new language or getting involved in art classes. It could either be a formal class or learning lessons on your own. The nerve cells will begin to grow and the connection would keep strengthening as long as you keep learning something new. You can also take up hobby-based classes such as painting or carving, which you always wanted to learn.
Such courses would strengthen the part of the brain that controls the spatial relations and would improve your ability to put things together. Getting involved in sports such as badminton or learning to play musical instruments can help you sharpen your hand-eye coordination along with reaction time reflex. Playing games like a crossword puzzle, chess, scrabble, etc., also keeps your brain active.
2. Diet and supplements
A deficiency in vitamin B12 or B6 can cause deterioration of the nervous system leading to memory loss. After 40, one should focus on a diet that is high in Vitamin B6, B12 and folate. B6 can be found naturally in beans and pulses. B12 is found in meat and dairy products. Folate can be obtained from spinach, beans, fortified cereals and asparagus.
3. Social interactions
For good brain health and overall wellness, one should maintain a network of connections with other people. When connected strongly to other humans (family and friends), one is less likely to face stressful situations.
When you keep your body fit, your mind also stays fit. Middle-aged people are always advised to indulge in yoga, aerobic exercise or martial arts regularly in order to boost their mental ability. Research has also shown that walking regularly for at least 3 days a week can give a 15 per cent boost in mental functioning. When there is an excess level of cortisol (a stress hormone), the hippocampus shrinks. Indulging in yoga, meditation and breathing exercises can help in reducing stress levels.
Avoiding smoking and excess alcohol along with getting enough sleep also goes a long way in keeping your brain healthy and young.
Recent Discoveries In Brain Ageing
Continuous research has led to several discoveries that aim at solving the brain-ageing conundrum. A couple of them are as follows:
1. Stem cells
Research students along with the guidance of their faculty have discovered the fact that the stem cells in the brain's hypothalamus are responsible for controlling how fast ageing occurs in one's body. The research also reported that by replenishing stem cells, it is possible to slow and even reverse some of the aspects of ageing.
2. SuperAgers 
SuperAgers is a term used for a group of people who are 80 years of age or above but possess memories as sharp as any healthy person decades younger than them. Research conducted revealed that the brains of SuperAgers shrink at a much slower rate compared to other people their age. This allows for resistance to the typical memory loss that is ideally observed with age (this reveals that age-related cognitive decline is not inevitable).
It is clear that changes in the brain occur with chronological age, however, it is yet to be completely proven as to at what rate the change happens when attributed to the biological age of the brain.
A lot of research is still under progress to identify the true mechanisms of ageing and find ways to alleviate the age-associated disorders (in particular, dementia). Studies have also shown that a healthy lifestyle, which aims at reducing cardiovascular risk, benefits the health of the brain to a great extent.
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