Improvements in vocabulary, better big-picture thinking and greater empathy rank among upsides to the aging brain. But it's worries about the downsides that are compelling Americans to spend more than $1 billion on "brain fitness," a number that will continue to rise dramatically, according to market research firm SharpBrains.
The "brain-training" site Lumosity, launched in 2007, now has about 40 million subscribers, most paying $14 per month. The question is, can "brain exercises" actually improve mental capacities, in particular those that decline with age?
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Among these capacities, Lumosity claims to improve attention, flexibility, problem-solving and working memory, the last defined as the ability to hold several units of information in the mind and manipulate them over a short period of time.
Interest in brain training got started in the early 2000s after new evidence demonstrated that the brain, whose abilities were thought to be fixed in early life, had unimagined plasticity.
Brain scans on London cabdrivers, required to memorize detailed maps of London neighborhoods, showed larger hippocampi -- structures in the brain that process memory and emotion -- than those of London bus drivers. The conclusion: The cabbies' intense memorizing had created new neuronal connections.
After that first surge, interest exploded. Most credit the 2008 study by Maryland psychologist Suzanne Jaeggi, Michigan psychologist Martin Buschkuehl and others, in which subjects in their mid-20s were trained on one memory challenge, called the dual n-back, for anywhere from eight to 19 sessions lasting 25 minutes each, while a control group received no training. The result: The more hours of training, the bigger the gain in "working memory," and, thus, of problem-solving ability.
Attempts to replicate the study by Michigan State psychology professor David Hambrick, however, ran into trouble. Using eight different challenges instead of one, and 20 sessions of training, Hambrick sums up his findings as "zip." He makes the point that "just because you get better in one doesn't mean you're smarter."
To judge brain-training exercises, an important variable is generalizability -- whether specific brain exercises lead to improvements on other tasks and in other areas. Does getting better at remembering random letters or numbers mean that you won't put your car keys in the freezer?
Based on meta-analyses (studies that combine the results of many studies), Yale neurologist Steven Novella concludes, on the website he founded called Science-Based Medicine, that "memory training programs appear to produce short-term, specific training effects that do not generalize."
Novella sees computer-based brain training as having potential for "maintaining and improving cognitive function" and believes that "existing research is inadequate to rigorously address all variables of brain-training interventions."
More studies need to be done. In addition, he says, "The very concept of brain training is probably flawed. Just a fancy term for good old-fashioned learning. … It's just learning."
While Lumosity's brain exercises -- from visually tracking the direction of one bird in a flock to creating words from small roots -- can be fun, the dual n-back, the exercise used by the Maryland researchers, requires subjects to keep track of two separate streams of stimuli, usually one auditory and one visual.
For example, while a subject watches a series of letters on a screen, he or she listens to a series of numbers, and then each of these series is regularly interrupted with a request for the subject to name the letter or number that he saw or heard one or two steps back or more.
Although whole websites are devoted to this exercise, Hambrick's negative findings may be a relief for anyone who has felt obliged to include it in their brain training.
In a 2013 New Yorker article, author Patricia Marx describes her experiences, first undergoing an online "Brain Fitness Check-up" designed by the Washington-based company NeoCorta and then choosing the brain-training platform BrainHQ, developed by Posit Science.
Posit's founder Michael Merzenich told Marx that the program "effectively reversed cognitive aging by 11 years, on average, after only 10 hours of training." Marx trained for one hour every day for six weeks and filled out many questionnaires, after which she was told, "Your advances on these exercises come from brain remodeling" and that her "enhanced brainpower should last several years."
Marx said she didn't notice her newfound cognitive abilities but adds, drolly, is now "slightly less troubled about the size" of her hippocampus.
Working-memory deficits, however, can also be caused by stress, both ongoing and post-traumatic, and dealing directly with its effects can stimulate a marked improvement in working memory at any age. Currently, the most-touted antidote to all kinds of stress is mindfulness, and the program that for more than 30 years has helped soldiers, firefighters and thousands of others impaired by stress-related memory deficits is Mindfulness Based Stress Reduction (MBSR), an eight-week course developed by Jon Kabat-Zinn at the University of Massachusetts Medical Center.
An appealing alternative to cognitive "brain training" exercises is "neurobics," exercises that involve employing any one of your senses in a new way; for example, writing or brushing your teeth with your non-dominant hand. (See "Keep Your Brain Alive: 83 Neurobic Exercises to Help Prevent Memory Loss and Increase Mental Fitness," by Lawrence Katz and Manning Rubin.)
In a recent book, "Smarter: The New Science of Building Brain Power," Dan Hurley spent several months using several resources at once: Lumosity, the dual n-back challenge, intense physical exercise, mindfulness meditation and learning to play the Renaissance lute -- as well as two other potential cognitive enhancers, the nicotine patch and transcranial direct-current stimulation.
Test results were ambiguous, but Hurley writes, "I got along better with my wife and daughter, I no longer found myself getting into my car and realizing that I'd forgotten my briefcase. … I feel smarter."
Reading books, the old-fashioned alternative for exercising the brain -- and not necessarily highbrow material -- was studied recently at Emory University. Twenty-one students who read the page-turner "Pompeii," about 30 pages a day for nine days, received functional MRI scans on the five days before and after the reading, as well as on each of the nine days once that day's assignment had been completed.
Post-reading scans showed heightened connectivity -- the goal of brain training -- in two areas of the brain, called "shadow activity" because it's seen after the activity is finished.
The conclusion: Simply thinking about movements performed by the book's characters activated neurons in the reader associated with the physical act of moving. Said the study's lead author, Emory University neuroscientist Gregory Berns, "Reading a novel can transport you into the body of the protagonist" -- exercising your brain, not just figuratively, but "something may also be happening biologically."
So don't toss your thrillers.