The market for brain-training software continues to grow, but evidence of the programs’ ability to boost memory or intelligence in a broadly applicable way (rather than simply making people better at the task they are practicing) remains scarce. New studies offer a tantalizing suggestion that certain programs may work—but the bulk of the research is murky.

Neuroscientist Peter Snyder of Brown University reviewed nearly 20 software studies and concluded that, as a group, they were underwhelming. They are marred by flaws that induce confounding factors, such as a lack of control groups and follow-up, Snyder warns. More than a third of those he reviewed were too shoddy even to include in the analysis he printed early this year in the journal Alzheimer’s & Dementia. “You’d be surprised at what gets published,” he says. Although some products claimed to treat dementia, Snyder did not find any evidence to back such claims.

One paper, however, exceeded expectations: in a new study Snyder called the “most well-designed” of those he evaluated, the Mayo Clinic tested the Brain Fitness Program by Posit Science. [For a review of this and other programs, see “Brain Trainers,” by Kaspar Mossman; Scientific American Mind, April/May/June 2009.] Encouragingly, the researchers found that the software boosted the brain in ways unrelated to the training. Rather than simply learning to parrot back what they had practiced, participants improved their test scores across a range of brain functions, says clinical neuropsychologist Glenn Smith, who led the study.

People who used the program bolstered their working memory—the system that holds information in mind momentarily in tasks such as dialing phone numbers—and processing speed, two assets that deteriorate with age.

Still, the boost was minimal. Subjects who played improved their memory by twice as much as did those in the control group (who spent an equal amount of time watching educational documentaries). After eight weeks of training, that improvement was only about 4 percent. Small effects such as those are a hallmark of brain-training software studies, Snyder says. He adds, however, “This is a good first study to emerge out of a terribly messy literature,” and he would like to see if it can be replicated. Posit Science funded the study, but none of the researchers involved has a financial stake in the company.

Although the magnitude of improvement may be small, training’s effect on the brain is visible, according to another recent study. In February neuroscientists at the Karolinska Institute in Sweden used PET and functional MRI scans to reveal changes in the number of receptors for dopamine—a chemical messenger involved in learning, among other important functions. Whether volunteers started with a relatively low or relatively high number of dopamine receptors, brain training resulted in a shift closer to the optimum balance.

“We know that the brain is plastic,” says Torkel Klingberg, the lead neuroscientist for the investigation. “But nobody has shown that the biochemistry of the brain is plastic in this way.” He developed the program used in the study, called Cogmed Working Memory Training, and he has shares in the company.

Snyder praised Klingberg’s study but also pointed out that it is a given that the brain will change in response to a variety of interventions. From his perspective, software companies remain hard-pressed to prove their products do much, especially over the long term, and few programs have demonstrated the flexibility to boost skills that were not practiced.

The best memory enhancer is exercise, Snyder says. [For more on exercise and the brain, see “Fit Body, Fit Mind?”] Secondarily, a good diet and an active social life have brain benefits. Does software improve on those standbys, he asks? “Frankly, I have my doubts. The evidence isn’t in.”

Note: This article was originally printed with the title, "Brain Training's Unproven Hype."