January 30, 2014

How the Brain Ages

I stumbled upon an interesting site called “A Health Blog” that describes how the brain ages. Here are the highlights:

Gestation:
  • The brain begins to grow four weeks after conception.
  • At certain times during brain development, 250,000 neurons are added each minute. That’s hard to fathom!
  • Shortened gestation can disrupt brain development, which may cause behavioral and psychological problems later.
Childhood:
  • The brain produces twice the number of neurons it will need, and only those that are reinforced with use will remain.
  • The brain is as energetic and flexible as it will ever be during this time.
  • By age 6, the brain reaches 95% of its adult weight.
Adolescence:
  • While the brain is now fully grown, the “wiring” process continues.
  • This period brings “waves of gray-matter pruning.” Teens lose about 1% of their gray matter each year until their early 20s.
  • Some suggest that our brains start to age as soon as we hit puberty.
Adulthood:
  • During a person’s 20s, the brain reaches adulthood.
  • Brain power peaks around age 22 and lasts only about five years.
  • What functions begin to decline? Planning and recalling events, and task coordination.
  • Between ages 20 and 90, the brain loses about 5-10% of its weight.
  • Between ages 45-49, we’ve lost about 3.6% of our gray matter. Memory, reasoning, and comprehension start to wane.
  • Grooves on the brain’s surface widen.
Old Age:
  • We’re steadily losing brain cells.
  • Our brains essentially dry out as we age. Drinking lots of water won’t help; living in dry climates won’t hurt.
  • Decayed portions of dentricles that extend from neurons increase.
  • Between ages 65-70, men have lost about 9.6% of their gray matter, and women about 7.4%.
  • By age 80, brains have shrunk and lost a few ounces, mostly water.
  • Brain shrinkage impairs cognition, affecting inductive reasoning, spacial orientation, and verbal memory. Shrinkage in the hippocampus leads to orientation loss and wandering.
  • Some positive news: the amygdala interacts more with a part of the brain that controls emotion.
Factors that May Affect Brain Aging
The Positive:
  • Education: keep learning and keep brain active.
  • Exercise: rapid walking for 45 minutes three times a week.
  • Rest: Eight hours of sleep a night may retard memory loss.
  • General health: eat wisely, don’t smoke, maintain good blood pressure and cholesterol levels.
The Negative:
  • Hypertension: accelerates brain shrinkage and cognitive impairment.
  • Stress: releases the hormone cortisol that in large amounts erodes neurons in the hippocampus.


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