Exercising the Brain to Avoid Cognitive Decline

Examining the Evidence

William E Reichman; Alexandra J Fiocco; Nathan S Rose


Aging Health. 2010;6(5):565-584. 

In This Article

Cognitive Training Approaches to Protect Brain Health in Later Life: Case–control Studies

Two Types of Training Approaches

Two approaches towards cognitive training studies have been taken, compensatory and restorative. Compensatory training approaches teach new ways to accomplish a cognitive task by working around cognitive weaknesses or deficits. This is done by training strategies such as categorizing or visualizing information that is to be remembered, as well as utilizing external memory aids such as notes, calendars or other environmental cues.[43] Restorative approaches seek to strengthen specific cognitive domains in order to improve functional performance more generally. For example, participants of some studies practice memory and attention games with the hope of improving those domains in general. The idea behind restorative training is that training on one task might enhance the cognitive ability or abilities that are needed to perform similar tasks (near transfer) or very different tasks such as activities of daily living (far transfer). Whereas compensatory approaches tend to only produce near transfer effects by benefiting the specific training task or domain that was targeted by the training program, far transfer effects through restorative training are considered the 'holy grail' because they suggest cognitive functions can be enhanced beyond the specific domain of training. To date the training studies that have been conducted have used either compensatory or restorative (or both) types of approaches to assess the impact of cognitive training on brain health.

Cognitive Training Interventions in Healthy Elderly: Case–Control Studies

In a meta-analysis of the cognitive exercise literature, Valenzuela and Sachdev conducted a systematic review of randomized clinical trials with a longitudinal follow-up.[44] Of the 54 identified studies, only seven published trials involving approximately 3000 participants, possessed eligible criteria for inclusion which included randomization, repetitive training over separate days for more than 1 week, longitudinal follow-up beyond 3 months and participation by healthy community-dwelling older adults of more than 50 years of age. Participants with any cognitive impairment, including dementia were excluded, as were individuals with a major neurological or psychiatric disorder. The major search engines included MEDLINE, PubMed and key references. The studies examined in this review focused on techniques to improve cognitive performance in reasoning, memory, information processing speed, problem-solving and attentional ability. Many of the studies included a combination of both compensatory and restorative types of cognitive training. Pre- and post-intervention scores were integrated using a random effects weighted mean difference (WMD) meta-analytic approach. The investigators concluded that cognitive exercise training in healthy older adults produces strong and persistent protective effects on longitudinal neuropsychological performance, particularly in the domains that were of major focus for the intervention. The effect size was reported as strong for cognitive exercises compared with a control condition (WMD: 1.07; 95% CI: 0.32–1.83; z = 2.78; n = 7; p = 0.006; n = 3;194). Far transfer was only reported in some of the studies. Notably, the authors concluded that although cognitive exercise demonstrated protective effects on neuropsychological function, it has yet to be shown to prevent incident dementia.

Papp and colleagues also reviewed the state of the literature on immediate and delayed effects of cognitive interventions in healthy elderly individuals.[45] Their review utilized five electronic databases: MEDLINE, Scopus, the Cochrane Collaboration, Dissertation Abstract International, PsychINFO and two registers: Current Controlled Trials and Clinicaltrials.gov. Only studies that were randomized, written in English and published after 1992 were included for evaluation. Study participants had to be healthy community residing elderly. Using these criteria, ten studies met inclusion for their meta-analysis. The authors found a post-training mean weighted effect size (Cohen's d) of 0.16 (95% CI: 0.138–0.186), which represents a small, but significant benefit of cognitive exercise. However, they concluded that the existing literature is limited by a lack of consensus on what constitutes the most effective type of cognitive training, insufficient follow-up times, a lack of matched active controls and few outcomes demonstrating transfer of any cognitive gains to daily function or global cognition. This analysis also failed to detect any evidence that cognitive training prevents the incident AD in healthy older adults.

Included in both of the above analyses is the largest and perhaps most informative study ever carried out examining the long-term effects of cognitive training in healthy older adults: the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study. It included 2832 volunteer participants, with a mean age of 74 years and was conducted in multiple sites. Participants were recruited from senior housing, community centers, clinics and hospitals. The intervention consisted of ten small group sessions designed to train one of three cognitive areas: memory, reasoning or processing speed.[46–48] Training sessions lasted 60–75 min each and were led by a certified trainer. The memory training sessions consisted of learning mnemonic strategies (organization, visualization and association) for recalling word lists and texts (verbal material) followed by practice using those strategies. Reasoning training included learning and practicing strategies for finding and completing patterns in a letter/word series. Speed of processing training involved learning how to effectively visually search and divide attention by doing challenging tasks on a computer screen.[46] Participants were randomized into one of the three training groups or a fourth control group. In a random sample of those who completed initial training, four 'booster' training sessions were provided at 11 months and 35 months. Assessments were conducted at baseline, immediately following the intervention and then at 1, 2, 3 and 5 years follow-up. The immediate ACTIVE results demonstrated improved cognitive function in each of the three domains targeted for intervention. These improvements were maintained through 2 years of follow-up, although no far transfer effects were observed.[48] Willis and colleagues specifically reported data on the 5-year follow-up of the initial study.[46] Approximately two-thirds of the original sample was available. As compared with controls, those who had been randomized to the reasoning training conditions had less functional decline in self-reported instrumental activities of daily living (IADLs) at the 5-year mark (effect size: 0.29; 99% CI: 0.03–0.55). This effect on function was not seen in either the memory or speed of information processing groups. However, all three groups maintained the specific cognitive domain improvement initially reported at the beginning of the study. Further, the booster training for speed of information processing, but not for the other two groups, led to a significant performance-based cognitive improvement.

In summary, this study demonstrated that specific-domain cognitive training, as compared with a control condition, improves ability in specific targeted domains, which persist for at least five years in study completers. In terms of maintaining functional ability in IADLs, only reasoning training seems to have had this specific positive effect. Wolinsky and colleagues reported that the ACTIVE trial interventions also had a positive impact on well-being by mitigating decline on health-related quality of life measures. Specifically, they reported that at the 2-year follow-up, there was a protective effect demonstrated by the speed of processing, but not for the memory or reasoning interventions. However, at the 5-year follow-up, all intervention groups demonstrated a protective effect on decline in health-related quality of life.[49] This latter point is important because it suggests that, unlike many medical treatment interventions, participants in this cognitive training program did not appear to experience any negative side effects of treatment and some even appeared to have experienced an enhanced quality of life.

Mahncke and colleagues conducted a study assessing the potential benefits of a computerized cognitive training program developed by a commercial entity, Posit Science.[50] The 'experimental' group engaged in six computer-based exercises of increasing difficulty tied to gains in performance using the Posit Science Program. This involved using the program in 1-h sessions, five-times per week for 8–10 weeks. The 'active control' group accessed a computer-based educational program on how to maintain good cognitive health and were asked to recall what they had learned. The 'no contact' control group received no intervention. Compared with the control groups, the experimental group demonstrated an immediate improvement in specifically trained cognitive domains including speed of processing and a variety of verbal memory related tasks.

In a larger follow-up investigation, Improvement in Memory with Plasticity-Based Adaptive Cognitive Training (IMPACT), Smith and coworkers further reported on the efficacy of the 'Posit Science Brain Fitness Program' in community residing older adults.[51] Participants were randomly assigned to two groups: an experimental group and an active control group. The experimental group used the Posit Science computerized training method while the active control group used computers to view educational programs on history, art and literature and then were quizzed after each training session on the content of the programs. All participants endured 1 h of training per day, 5 days a week for a total of 8 weeks. The investigators reported that on a standard neuropsychological test of auditory memory and attention (RBANS auditory memory/attention), the experimental group demonstrated significant (p = 0.02) improvement (3.9 points; 95% CI: 2.7–5.1) compared with the active control group (1.8 points; 95% CI: 0.6–3.0). Therefore, the computerized training method of Posit Science resulted in near transfer effects; however, it is unknown whether these were long-lasting effects or if there were any far transfer effects on more global or everyday cognitive functions.

In addition to enhancing cognitive performance, Engviv and colleagues reported on the effects of an 8-week intensive memory training program on cortical thickness in older adult participants.[52] Compared with the controls, memory trainers displayed increased cortical thickness of the right fusiform and lateral orbitofrontal cortex, which were both correlated with improvement in source memory performance. Although only short-term effects were examined, these findings support the notion of neuroplasticity in later life, and of enhanced brain reserve following cognitive training. However, longitudinal research is needed to determine the lasting effects of cognitive training on reserve.

Although exciting prospects are emerging, more research is required to determine the most effective type of cognitive training for protecting cognitive function and producing transfer to everyday life. With regards to cognitive training interventions in populations associated with pathological aging, the need for more research is even greater. Table 3 summarizes the cognitive training studies on healthy aging as well as those involving MCI and AD populations, some of which are reviewed in detail below.