Your brain ages, much like your arteries and lungs. And much unlike your arteries and lungs.
Think of an older brain as an older computer. They both store a lifetime of information, but sorting through it all becomes slower and labored. As we get older, we can’t multi-task the way we used to, we don’t learn as fast and our ability to reason rapidly with new facts declines. We may block on someone’s name: Studies show that name-face recognition ability declines about 50 percent between 25 and 75. We may forget where we left the car keys. And once we find them and get behind the wheel, our reflexive responses in traffic are likely to be slower than they used to be.
And in the back of our minds, of course, is the increasing risk of dementia as we age.
But here’s some good news: Neither long-term memory nor intelligence fades with normal aging. Indeed, the brain is the one organ that can actually improve with age in some respects. No other organ system has the equivalent of the accumulated brain power that comes with the brain’s capacity to keep absorbing knowledge, essentially metabolizing it into wisdom that can make up for slower processing time. Meanwhile, the amygdala region of the brain responds less actively to negative events as we age—a rare instance in which the aging process causes a decline in function that can actually make life easier.
So it’s not all bad. But the bad—declining cognitive function—is of course what people worry about. So is there an objective way of tracking and assessing that decline? Is there a biomarker for brain aging that can be used to detect and intervene in a downward trend that, like other aging processes, starts decades earlier? And are there steps you can take to keep your brain healthy and reduce your risk of cognitive decline and even perhaps Alzheimer’s?
Some aspects of your cognitive function have been declining since as early as your mid-twenties, but they are so gradual and subtle that you wouldn’t notice them unless you happened to compare your performances in a video game, say, or did long division in your head.
Functional neuro-imaging tests can measure changes in brain functon, but they are expensive and impractical. Neuropsychological testing is also expensive, as well as time-consuming. A test known as the Mini Mental State Exam screens for dementia and the risk of later onset, but it isn’t sensitive enough to pick up early cognitive aging.
There are, however, computerized cognitive tests—self-administered, electronic versions of manual tests—that can objectively assess most of the cognitive areas of the brain in a short time. They are relatively inexpensive and can be given annually to track changes over time.
One of these batteries of neuropsychological tests, CNS Vital Signs, is used by PhysioAge Systems as a biomarker of brain aging. The 25-minute series of tests assesses the main areas of cognitive function by challenging and taxing them more than they are in a typical person’s daily life. It screens for impairment from a range of neurologic conditions—from attention deficit disorder to dementia—as well as from medications. It’s a screening test that everyone should take periodically, like the spirometry test of lung function that yields useful information about aging overall. But as with spirometry, the results of the cognitive test must be age-adjusted to be a valid marker of accelerated impairment.
While most areas of cognitive function are affected by normal brain aging, two are particularly sensitive to age and start showing changes in early adulthood. These are reaction time and processing speed. The CNS battery includes a test for each that can indicate the onset of what’s called mild cognitive impairment (MCI)—accelerated aging of cognitive function that increases the risk of dementia.
One test is a timed measure of how many paired sets of symbols and digits one can see on a computer monitor and then press the corresponding key on the keyboard. The other test records how quickly and accurately a person presses the space bar when a word on the monitor spells the color of its typeface. It then tests response time and accuracy when the test taker is asked to do the opposite—press the space bar as quickly as possible when, for example, the word “blue” appears in red.
The results of these tests, adjusted for age, indicate whether the person’s brain function might be aging more rapidly than it should be. Because these adverse results can occur even in the absence of memory loss, they can be a warning for early brain disease.