MEDITATION and mindfulness: the words conjure images of yoga retreats and Buddhist monks. But perhaps they should evoke a very different picture: a man in a deerstalker, puffing away at a curved pipe, Mr. Sherlock Holmes himself. The world’s greatest fictional detective is someone who knows the value of concentration, of “throwing his brain out of action,” as Dr. Watson puts it. He is the quintessential unitasker in a multitasking world.

Though the concept originates in ancient Buddhist, Hindu and Chinese traditions, when it comes to experimental psychology, mindfulness is less about spirituality and more about concentration: the ability to quiet your mind, focus your attention on the present, and dismiss any distractions that come your way. The formulation dates from the work of the psychologist Ellen Langer, who demonstrated in the 1970s that mindful thought could lead to improvements on measures of cognitive function and even vital functions in older adults.

The concentration benefits of mindfulness training aren’t just behavioral; they’re physical. In recent years, mindfulness has been shown to improve connectivity inside our brain’s attentional networks, as well as between attentional and medial frontal regions — changes that save us from distraction. Mindfulness, in other words, helps our attention networks communicate better and with fewer interruptions than they otherwise would.

Mindfulness training has even been shown to affect the brain’s default network — the network of connections that remains active when we are in a so-called resting state — with regular meditators exhibiting increased resting-state functional connectivity and increased connectivity generally. After a dose of mindfulness, the default network has greater consistent access to information about our internal states and an enhanced ability to monitor the surrounding environment.

The implications are tantalizing. Mindfulness may have a prophylactic effect: it can strengthen the areas that are most susceptible to cognitive decline. When we learn to unitask, to think more in line with Holmes’s detached approach, we may be doing more than increasing our observational prowess. We may be investing in a sounder mental future — no matter how old we are.