The Aging Brain
The longevity that humans now enjoy is recent, and one for which evolution has not fully equipped us. The most important organs of cognition – the mind-brain – inexorably decline, even in the healthiest person.
The brain at 80 weighs 10% less than at 20. Tissue loss between adolescence and old age is 20–30%. The areas responsible for higher cognitive functioning are most affected.
The aging brain is less tolerant of noise, as filtering meaningful signals becomes more demanding. The sensory clutter that stimulates young brains becomes insufferable.
The senses also suffer with age. Smell sensitivity is particularly prone to loss, and with it zest in taste. As food losses appeal it becomes less important.
The rate of the diminution in brain wattage is highly variable. Maintaining physical and mental fitness by regular exercise prolongs mental acumen and aids memory retention, as does keeping active socially.
One of the best exercises for maintaining mind-brain acuity is walking, as it exercises both the senses and sensation. Knowing this reminds that the brain is just an organ of the body. An out-of-shape physique spells an out-of-sorts brain.
Time with the mind-brain in repose is equally important. Resting the mind through meditation is a powerful form of rest. Getting enough sleep is crucial to health; something which too few do in industrialized countries, especially those with ambition.
Not stuffing the body is as important as exercise and rest are to keeping fit. Reducing caloric intake is significant in reducing the pace of aging, including the mind-brain.
As the brain ages, memories fade as astrocytes and attendant nerve cells are lost in critical areas such as the hippocampus. Decay in the myelin sheath that insulates and regulates neural communication is a common symptom of an aging intelligence system.