Physically what happens to our brain as years go by....

Research has shown that as brain ages or as people get older, there will be a decrease in brain weight and brain volume, widening of the grooves on the surface of the brain and enlargement of the ventricular system (ventricles- a cavity or hollow part of the brain).

The decrease in brain weight and brain volume are probably due to loss of neurons (specialized cells transmitting nerve impulses) and extra cellular fluid. Man may have a 20% reduction in brain weight between the ages of forty -five and eighty -five and lose thirty to fifty thousand neurons a day from the brain and nervous system as they age. Enlargement of the ventricular system may be probably due to loss of cells surrounding the ventricles (the spaces in the brain that contain cerebrospinal fluid). 

Probable reasons for the change...

Surprisingly there is a certain percentage of people who function very normally even when they age. So the causes of loss of memory, concentration, focus and the inability to function independently as man ages may not be only due to the aging itself as previously thought. But may be due to a combination of other factors like Brain-unhealthy behaviour and habits, insufficient mental stimulation, limited thought or response control strategies, brain unhealthy diet or inadequate supplements, lack of novel experience, lack of sufficient social interactions and cooperation etc. 

Ways to delay effects of aging...

To stay mentally sharp, you need to work your mental muscles each and every day. Get involved in something that keeps your brain busy such as taking up a new class, exercise, yoga, martial arts, mind games etc. Any activity that involves concentration will help exercise the mind and keep it strong. 

Mental stimulation

After 40, taking up a new language or any new course or art classes, whether joining a formal class or learning on your own is beneficial. As long as you learn something new, the nerve cells in your brain will grow and the connection between them will continue to strengthen.

As you age, find time to take up any art lessons like painting, wood working etc. that you always wanted to pursue but never had the time earlier. These help strengthen the part of the brain that controls spatial relations, the ability to recognize how things piece together.  

To sharpen the hand -eye coordination and reaction time reflex, getting involved in some sports like table tennis, badminton etc. or playing any music instruments and video games in the computer helps. 

Get knowledge from books and try to keep remembering them to enhance your memory. Regular reading of a variety of news papers is also helpful. Keep your brain active and sharp by playing like chess, cards, scrabble and doing crossword puzzle, jigsaw puzzles etc. 

Social Interactions

Having a network of connections to other people is beneficial for brain health and well-being. Humans appear to benefit and function more optimally when connected to other humans in a socially organized network. It is seen that people with a strong support network of family, friends, and acquaintances are less susceptible to stress-related problems. 

Exercise

Keeping your body fit also keeps your mind fit. Practicing yoga, long term aerobic exercise or martial arts regularly during middle age is beneficial for boosting the brain. Standing on one foot for as long as possible and then switching to the other foot and repeating is a simple exercise which improves motor coordination that can be done at any time and without any special equipment. Try and see whether you can stand for thirty seconds, then slowly for longer periods and so on.

Excess levels of cortisol, a stress hormone, may shrink the hippocampus, a part of the brain that's needed to form certain types of memory. Yoga, meditation and breathing exercises which help to increase the action of the immune system along with socializing (sharing with others) are effective in lessening stress. 

Recent research suggest that oestrogen therapy may improve both verbal and visual memory in postmenopausal women with Alzheimer's. Along with the above factors, avoiding smoking, abuse of drugs, excess alcohol and getting enough sleep goes a long way in keeping your brain healthy and young.