By 2020, people age 65 and older will outnumber children under 5, according to a United Nations report. At first glance, that's a good thing; most people born in 1900 did not live past age 50.
But age increases the risk for long-term, intractable illnesses of the body and brain. By 2050, the World Health Organizationopens in new window estimates, 135 million people worldwide will have dementia.
To help psychologists understand the brain changes associated with aging, the APA journal Neuropsychology devoted its November issue to the topic, an area that has taken off over the past decade, says the journal's editor Gregory Brown, PhD.
"Psychologists have been … leaders in developing experimental designs and reliable measures for cognitive assessments, and also for statistical analysis of data," says Brown, who also directs the NeuroImaging and Behavioral Analysis Laboratory at the University of California, San Diego. "Now, we're looking at the exciting potential of integrating the information we've gained over the years with neurobiology and the cellular effects of aging."
As an example of information that neuropsychologists have gained about aging, one study in the special issue monitored the daily activities of 698 physically healthy people ages 74 to 84 over 10 years. The researchers found that even everyday cognitive tasks — calculating when a prescription refill is needed, or looking through a phone book — declined over time, despite scientists' previous assumptions that these skills remained relatively stable. The researchers also found a parallel decline of reasoning ability, suggesting that decline in executive function might play a greater role in limitations of daily activities associated with aging than memory decline (see graphic).
The special issue also includes several articles on decision-making and the frontal cortex and on the aging person's ability to hold and manipulate information and to multitask. "These things change with aging, [and] may be more critical to daily life than memory, which most people can work around," Brown says.
Another study in the issue looked at errors in daily activities that healthy people make as they age and compared them with patients who had mild cognitive impairment or dementia. The Washington State University researchers asked participants to perform basic daily activities, such as cooking soup or answering the phone, and watched as they completed them. Healthy older adults were less efficient at tasks overall, often having to search multiple locations for items, correct mistakes or repeat a step. But the study participants with cognitive impairment omitted key steps from the same tasks or did alternate actions, dusting the kitchen instead of the living room, for example.
Four additional studies in the issue discuss neurobehavioral aspects of Parkinson's disease, which is the second most common neurodegenerative disorder after Alzheimer's. The condition causes a loss of neurons in the mid-brain that also occurs — though at much slower pace — in normal aging, and so these studies might provide a model for understanding aging as well as new information about the disease itself, Brown says.
Also in the issue is a quantitative reviewopens in new window from the University of Victoria, which looked at the effect physical activity and cognitive training have on executive function, which generally declines even in healthy seniors. Both interventions led to improvements in cognitive function in healthy people — an optimistic finding in what can be a melancholy field of study.
"This kind of paper is challenging the old idea that aging produces immutable changes," Brown says. "We can reduce the rate of decline with focused interventions. That's a scenario we're just beginning to study."
