Long-Term Effects of Cognitive Speed Training

By Irene Yeh 

Cognitive training is known to have short-term and long-term benefits for cognitive performance. In the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study, funded by the National Institutes of Health, it was reported that participants demonstrated improvements after the initial cognitive training. Notably, “booster sessions” held at 11 and 35 months after the first training resulted in an even lowered risk of dementia. 

Published in Alzheimer’s & Dementia: Translational Research and Clinical Interventions (DOI: 10.1002/trc2.70197), the goal of this study was to determine the impact of ACTIVE’s cognitive training on the risk of diagnosed Alzheimer’s disease and related dementias (ADRD) over a 20-year follow-up period.  

Training Sessions 

The study was designed as a four-arm, multisite, single-blind randomized controlled trial in a large and diverse sample. 2,802 participants (26% of which were minorities) were recruited from March 1998 to October 1999 in six metropolitan areas. The participants were aged 65 years and older; 76% participants were female and 70% were white. Participants were randomly sorted to one of four intervention arms, and staff members were also blind to which group the participants were assigned.  

Of the original 2,802 participants, 2,763 were matched to Medicare claims based on Acumen’s matching algorithm. The rest were excluded because of incomplete claims data that could cause inaccurate outcome measurements. Others were excluded because of death, or an ADRD diagnosis when they entered the study. The final sample size was 2,021 participants. 

Participants in three intervention arms received 60 to 75-minute training sessions in small groups over 5-6 weeks. These groups were: speed of processing training focused on visual search and the ability to process increasingly complex information presented in successively shorter inspection times; memory training focused on improving verbal episodic memory through instruction and practice in the use of mnemonic strategies; and reasoning training focused on improving the ability to solve problems that contained a serial pattern. The fourth group was the control group that did not have training. 

Participants who completed at least eight out of 10 of these training sessions were randomized again into booster training sessions at 11 and 35 months after initial training, each of which were up to four 75-minute sessions. These boosters were added because previous studies have shown that they improved the maintenance of training. 

Cognitive Training is Key 

Nearly half of the control group was diagnosed with ADRD within the 20-year follow-up period. Additionally, individuals in the speed group who did not complete the initial speed training sessions or partake in the booster sessions did not show significantly lowered risk of ADRD.  

The speed training group members that took part in booster training 11 and 35 months later, however, showed 26% lowered risk of ADRD. Those who only did the speed training sessions had around 19% of reduced risk. Repetitive task training is already established as useful and beneficial for other neurological conditions, such as stroke. The researchers theorized two possible reasons for the significant improvements of the speed training with the booster sessions. The first is, simply put, more training leads to better outcomes. The second reason is that the booster sessions might have strengthened the training by adapting the participants’ improving abilities as the task difficulty increased.  

Speed-training focused on improving visual processing and attention, especially divided attention. Unlike the memory and reasoning training, speed training was done on a computer and adjusted automatically for each participant’s performance, increasing difficult as skills improved. In other words, this adaptive design might have led to broader brain activation, therefore strengthening the effectiveness of speed training. 

The research team found it surprising that the memory and reasoning training groups did not show significant results. A potential explanation for why this is the case is that memory and reasoning training mainly taught participants strategies to improve performance, whereas speed training did not. In other words, memory and reasoning training relied more on declarative memory (consciously learning and applying strategies) while speed training relied more on procedural memory (improving performance through practice without explicit instructions). However, earlier findings from the ACTIVE study showed that reasoning training was linked to fewer difficulties with instrumental activities of daily living 10 years after baseline. 

Cognitive aging is often linked to declines in controlled processes, such as attention and executive function, while problems with associative memory are typically among the earliest signs of preclinical Alzheimer’s disease. Because nearly all ACTIVE participants were cognitively healthy at baseline, it is possible that training programs targeting controlled processes—like speed training—were more effective in delaying the onset of ADRD. Future studies are encouraged to explore why reasoning and memory training from this study did not translate into decreased risk of long-term dementia. 

Limitations to Consider 

Some participants had other covariates, such as hypertension (66%), ischemia (40%), diabetes (21%), congestive heart failure (20%), atrial fibrillation (8%), and acute myocardial infarction (3%). These covariates, particularly the vascular risks, are associated with higher chances of dementia, and therefore the analysis was adjusted for cardiovascular conditions identified. Furthermore, 38% were former smokers, and this was also included in the analysis. 

Selection bias could have occurred due to participants who may have had better access to healthcare resources, attentive family members, or higher education levels, as these they were more likely to receive a dementia diagnosis. However, the ability to measure the cumulative incidence of dementia over 20 years using independently collected Medicare data is a major strength and likely outweighs these limitations. 

Another limitation includes that booster training sessions were offered only to a randomly selected subset of participants who completed at least eight initial sessions. This issue was addressed by comparing those who were randomized to receive boosters with those who were eligible but not selected. And finally, because the ACTIVE study has produced many publications, there is always a small risk of a false-positive finding. But this study is the first analysis that uses Medicare claims data, so the risk could be low. 

Cognitive speed training not only reduced the risk of developing ADRD, but it also demonstrated beneficial impacts on daily activities for the participants. For example, participants who completed speed training had fewer at-fault car accidents six years after the study, and those who completed booster sessions were more likely to maintain driving frequency. Cognitive training interventions could be included as part of multidomain interventions that can help slow cognitive decline and ADRD. Combining it with lifestyle changes, such as exercise and heart health monitoring, might work better than a single strategy and produce a stronger overall impact.