Cognitive function changes as we grow older
Q. I know I’m not as sharp mentally as I used to be. Is there anything I can do to improve my brain function? [The aging brain is a vast subject and one of deep interest to seniors, so I am going to do a three-part series on it.]
As a person gets older, parts of the brain shrink. Communication between nerve cells can be restricted. Blood flow in the brain may be diminished. Inflammation can increase. These changes in the brain can affect mental function.
The aging brain can make it difficult to recall words and names, do more than one thing at a time, learn something new and pay attention.
Some older people think efficiently, while others do not. One possible reason is what scientists call “cognitive reserve,” the brain’s ability to work well even when some part of it is disrupted. People with more education seem to have more cognitive reserve than others.
MRI studies show that older people take longer to shut down sections of the brain that have completed a task. This affects the brain’s efficiency and makes it difficult for the brain to take on several tasks simultaneously.
Imaging studies show that interconnected regions of the brain called the “default network” grow more active with age.
The default mode of the brain controls processes such as daydreaming. So, as we age, we spend more time daydreaming. And, if we are daydreaming, we can’t focus on tasks.
Normal changes that researchers think occur during brain aging include:
Brain mass. Shrinkage in the frontal lobe and hippocampus are areas involved in higher cognitive function and encoding new memories. This shrinkage starts at about 60 to 70 years.
Cortical density. This refers to the thinning of the outer-ridged surface of the brain because of declining connections between nerve cells. Fewer connections may contribute to slower cognitive processing.
White matter. White matter consists of nerve fibers that carry signals between brain cells. Researchers think that insulation protecting the nerves shrinks with age, so processing is slower and cognitive function is reduced.
Neurotransmitter systems. Researchers suggest that the brain generates fewer chemical messengers with age, and this decrease in dopamine, acetylcholine, serotonin and norepinephrine activity may play a role in declining cognition and memory, and increasing depression.
Older adults often become anxious about memory slips because of the link between impaired memory and Alzheimer’s disease. However, Alzheimer’s and other dementias are not a part of the normal aging process.
“SuperAgers” are a rare group of individuals over 80 who have memories as sharp as those of healthy people decades younger.
Research by scientists at Northwestern University compared SuperAgers with a control group of same-age individuals.
They found that the SuperAgers’ brains shrink at a slower rate than those of their age-matched peers, resulting in a greater resistance to the typical memory loss that occurs with age. This suggests that age-related cognitive decline is not inevitable.
By studying how SuperAgers are unique, the researchers hope to unearth biological factors that might contribute to maintaining memory ability in advanced age.
Fred Cicetti is a freelance writer who specializes in health. He has been writing professionally since 1963. Before he began freelancing, he was a reporter and columnist for three daily newspapers in New Jersey. If you would like to ask a question, write to [email protected].
