Knowing how the normal brain ages -- and how those changes affect your memory -- can make the occasional senior moment less worrisome.
We tend to think of our brain as different from our other organs. But the brain undergoes predictable changes over time, just like the heart. As with heart disease, good genes and a healthy lifestyle can moderate these age-related changes, but it can’t entirely stop them.
Contrary to popular belief, brain neurons (nerve cells) do not undergo a massive die-off with age. Evidence now suggests that some neurons are indeed lost, but the brain continues to grow new ones, albeit at a slower pace. What does happen is that nerve cells in the brain begin to shrink. As a result, the connections between neurons (synapses) begin to deteriorate over time, and chemical messengers (neurotransmitters) become less available to carry information. With advancing years, these age-related changes alter the transmission of nerve impulses through the brain, leading to slower cognitive processing and delays in recalling stored information. But in the absence of a brain-destroying condition like a stroke or Alzheimer's disease, these changes are mostly a nuisance and don’t interfere with a person’s ability to function successfully. A general time frame for normal brain aging is described below.
Normal brain aging – Your Twenties. People in their 20s are at the top of their mental game in terms of forming long-term memories and being able to engage in complex reasoning. Creativity, too, may be at its highest during these years, although twenty-somethings don’t have a lock on creative endeavors. Many writers, artists, and musicians are their most productive during this time. Slight physical changes in the brain, such as neuron shrinkage, start in a person’s 20s.
Normal brain aging -- Your Thirties. The brain continues to slowly lose volume through neuron shrinkage, but only a small amount. A formal battery of cognitive tests might show slight declines in some areas. But these small indications of cognitive slippage are usually not apparent to the individual or to others.
Normal brain aging – Your Forties. Most people will sense some slowing of their mental processing during their 40s, especially in the area of working (short-term) memory. Tasks like remembering phone numbers, doing mental calculations, or playing challenging card games may require more effort than they did in earlier years. The slow loss of brain volume continues and may begin to accelerate.
Normal brain aging – Your Fifties. The 50s are a threshold, the beginning of accelerated loss of brain volume and more noticeable changes in memory and other areas of cognition. Cognitive changes include:
- Processing speed slows further. It takes more time to recall names and words.
- Learning something new takes longer. Once learned, however, the information is usually retained.
- Multi-tasking (doing several things at once) becomes more difficult.
- Attention to detail wanes. You probably will remember fewer details of a novel, movie, or painting than a younger person would.
- Placing an event in time and place becomes more difficult. You may remember the event but not exactly when or where it occurred.
- Visuospatial processing is more difficult. This might translate into more trouble in copying three-dimensional designs or in reassembling an appliance.
Normal brain aging – Your Sixties. Loss of brain volume continues. The hippocampus and amygdala -- brain structures that are critical to memory and other cognitive abilities -- are particularly vulnerable. These structures may have shrunk by as much as 25% from their size in young adulthood. The cognitive changes that began in the 50s become more noticeable in one’s 60s. Cognitive processing speed may slow further, making it more difficult to learn new information or master complex mental tasks. It also becomes harder to concentrate and to “tune out” distractions. The brain is less adept at forming new memories and establishing the associations that enable us to recall stored memories. Tip-of-the- tongue experiences are more common because the brain has to work harder to retrieve names, dates, and words.
Normal brain aging – Your Seventies and beyond. People in their 70s and 80s vary widely in their cognitive abilities. Many not only remain quite sharp throughout these years but also gain in wisdom. For others, the wear-and-tear of high blood pressure, diabetes, heavy alcohol use, and other health problems will have taken a toll on memory and general cognitive ability. People who develop dementia typically begin to show signs of the disorder in their mid-to late-70s.
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Posted in Memory on August 27, 2007
Reviewed July 2009
