Cognitive decline associated with normal aging is inevitable. Objective measurements indicate that cognitive capacities begin to decline rapidly around age 50, and subjective complaints about decreasing cognitive skills begin even earlier (Young, Angevaren, Rusted, & Tabet, 2015). Cognitive decline is often associated with dementia, which causes any change in cognitive function to incite fear in older adults (Institute of Medicine [IOM], Board on Health Sciences Policy, & Committee on the Public Health Dimensions of Cognitive Aging, 2015). In a recent report, the IOM is explicit when differentiating between the cognitive decline associated with aging versus the reductions in cognitive function due to neurodegenerative disorders such as dementia (IOM et al., 2015). In this report, the IOM defines cognition as the mental functions used to participate in and accomplish normal daily activities, such as thinking, remembering, attention, and solving problems (IOM et al., 2015). Cognition is described as a highly variable, ongoing process that is affected by aging and results in changes in cognitive function; cognitive health can be defined as the ability of an individual to preserve optimal cognitive function for his/her age (IOM et al., 2015). In contrast, dementia is a progressive deterioration of cognitive function that primarily affects older adults (Barnes & Yaffe, 2011; Sindi, Mangialasche, & Kivipelto, 2015). The IOM emphasizes that, although dementia is of great public health concern, cognitive aging offers an opportunity for research to understand its complexities and attempt to identify factors that mitigate decline (IOM et al., 2015).
Current available research indicates that interventions such as physical exercise and cognitive training can slow the cognitive decline of older adults (Young et al., 2015). The recent IOM report identified the key modifiable risk and protective factors required to improve the cognitive health of older adults: diabetes and hypertension management, dietary habits, levels and frequency of physical activity, social and intellectual engagement, and cognitive training (IOM et al., 2015).
Although the preventive factors of cognitive decline span multiple health domains, most research involves trials of single-component interventions (e.g., physical activity or cognitive training alone) that target only one health domain. The findings from these single-component trials are conflicting and primarily show little or no improvement in cognitive outcomes (Plassman, Williams, Burke, Holsinger, & Benjamin, 2010). Evidence exists for an association between increased physical activity and lower rates of cognitive decline, but these findings are inconsistent and derived from short, small, and low-quality trials (Sink et al., 2015). Cognitive training studies show some promise, but assessments of cognition are not standardized and are limited to a single domain, such as memory or attention, which limits appraisal of data (Plassman et al., 2010). Overall, single-component studies to date have provided weak evidence that any one intervention is associated with significant benefits to cognitive health and reduced risk of cognitive decline.
It is likely that the mixed results and limited efficacy of single-component interventions is partially due to the complexity of cognitive health and various lifestyle-related risk factors related to its decline (IOM et al., 2015). Thus, the purpose of the current review was to identify and describe studies that involve multi-component interventions aimed at protecting the cognitive health of middle-aged and older adults and reducing the risk of cognitive decline. This evidence will identify gaps in current knowledge, inform future research efforts, and help guide the development of evidence-based preventive strategies.
A scoping review methodology was used because scoping reviews provide a preliminary assessment of existing literature in a specific topic area (Papaioannou, Sutton, & Booth, 2012). Scoping reviews are helpful when there may be a lack of high-quality studies for an exhaustive systematic review (Arksey & O'Malley, 2007). Scoping reviews also identify current gaps in research and offer implications for future studies. Multi-component trials are defined as trials that use more than one type of nonpharmacological intervention technique to target specific modifiable risk factors associated with cognitive decline, such as obesity, physical inactivity, and lack of intellectual engagement (IOM et al., 2015; Norton, Matthews, Barnes, Yaffe, & Brayne, 2014). Examples of intervention components that target these modifiable risk factors include nutritional guidance, physical activity, and cognitive training.
A literature search was conducted in July 2015 using the PubMed, CINAHL, EMBASE, PsycINFO, and Cochrane Controlled Trials Register databases. Search terms were developed with a University of Washington librarian experienced in database searches, and included: “cognitive health,” “aging,” “interventions,” “elderly,” “older adults,” “modifiable,” and “cognitive aging.” Using variations of key terms, databases were searched without date limitations or quality assessment criteria. In addition to a database search, a hand search of reference lists of relevant articles was conducted for possible inclusion. Search results were exported into an EndNote™ library and duplicates were removed.
A flowchart of the study selection process is shown in the Figure. Inclusion criteria were randomized trial design, two or more intervention components aimed at modifiable risk factors (i.e., obesity, physical inactivity, and lack of social and intellectual engagement), a focus on community-dwelling middle-aged and older adults, and a measurement of cognition as an outcome. Studies were excluded if they focused on participants with dementia, included only a single-component intervention, or did not measure changes in cognitive function.
Flowchart of study selection process.
Two authors (M.M.F., M.M.) jointly screened the 279 citations that were returned after the initial search, and 235 were excluded based on title and abstract. The two authors subsequently re-reviewed the abstract and titles of the remaining 44 articles independently using Covidence, an internet-based software screening and data tool developed for use in systematic reviews. Fourteen articles met criteria for full-text review. Any conflicts that arose (7%) were discussed with a third author (D.E.R.) with expertise in evaluating scientific evidence, and reconciled. After conducting the full-text review, 11 studies were excluded and three were selected for the final data extraction process. During full-text review, M.M.F. and M.M. identified 16 potentially relevant citations from reference lists. The full text of these 16 articles were evaluated by the two authors, yielding three additional studies that fit inclusion criteria, for a total of six completed studies included in the final data extraction.
Due to the small number of studies identified, the search was then expanded to include study protocols and studies in progress. Using the original 279 citations, the two authors jointly identified 17 additional articles for full-text review. After further screening, four studies with results in-progress met criteria and were included in the final data extraction.
Data Extraction and Synthesis
For the completed studies, a data extraction tool was developed by the first author (M.M.F.) based on the data extraction form described by Papaioannou et al. (2012). Extraction forms were completed for all studies by M.M.F., and a second author (M.M.) subsequently evaluated and verified the abstracted data. Disagreements (<5%) were discussed and reconciled in conjunction with a third author (D.E.R.). For articles that presented studies in progress, M.M.F. summarized the key elements of the study in a spreadsheet and M.M. confirmed all details.
Quality Assessment of Completed Studies
The methodological quality of the completed trials was assessed using the Downs and Black (1998) rating scale tool, which has high reliability and validity for assessing randomized studies. The tool comprises 26 items assessing reporting (9 items), external validity (3 items), bias (7 items), confounding (6 items), and power (1 item). Items were scored 0 or 1 (yes or no), except one item in the reporting of principal confounders scored 0 to 2 (the scoring for the item on statistical power was simplified to award either 0 or 1 point). The maximum possible score was 28. Methodological quality scores were grouped into four quality levels: excellent (26 to 28 points), good (20 to 25 points), fair (15 to 19 points), and poor (≤14 points). Two authors (M.M.F., M.M.) independently performed the quality assessment. Disagreements (6.4%) were discussed with another author (D.E.R.) and reconciled.
The characteristics of the six completed studies are presented in Table 1. Five studies were conducted in Europe (Clare et al., 2015; Fabre, Chamari, Mucci, Massé-Biron, & Préfaut, 2002; Forte et al., 2013; Ngandu et al., 2015; Oswald, Gunzelmann, Rupprecht, & Hagen, 2006) and one was conducted in the United States (Small et al., 2006). All six studies were conducted between 2002 and 2015.
Overview of Completed Multi-Domain Intervention Trials
Most intervention durations ranged between 2 months and 2 years, except Small et al.'s (2006) study of 14 days. In most studies, interventions were conducted weekly for 60 to 90 minutes (Fabre et al., 2002; Forte et al., 2013; Ngandu et al., 2015; Oswald et al., 2006). All studies included at least one intervention domain focusing on cognitive training and physical training each. Education, mentoring, or interviewing were common cognitive training strategies that were used (Clare et al., 2015; Ngandu et al., 2015; Small et al., 2006), and physical exercise resistance training and relaxation techniques were examples of physical intervention strategies (Clare et al., 2015; Forte et al, 2013; Small et al., 2006). Four studies used a more interactive form of group cognitive and/or physical training sessions (Fabre et al., 2002; Forte et al., 2013; Ngandu et al., 2015; Oswald et al., 2006). For example, Ngandu et al. (2015) included scheduled social activities, in addition to physical exercise and cognitive training programs, as interventions. Control groups were used in five of the six studies (Clare et al., 2015; Fabre et al., 2002; Ngandu et al., 2015; Oswald et al., 2006; Small et al., 2006).
Cognitive Function Results
Most studies measured changes in global cognition and memory (Fabre et al., 2002; Forte et al., 2013; Ngandu et al., 2015; Oswald et al., 2006; Small et al., 2006). Four studies examined additional domains, such as processing speed, executive function, and reasoning (Clare et al., 2015; Forte et al., 2013; Ngandu et al., 2015; Oswald et al., 2006). Cognitive measures were primarily task-based and included the Wechsler Memory Scale, Trail Making Test, Visual Paired Associates Task, Memory Functioning questionnaire, BEC-96 questionnaire, and Neuropsychological Test Battery (NTB) (Table 1).
All completed trials showed significant improvements in at least one domain of cognitive function; however, the specific intervention domains that each study examined varied. For example, in the study by Ngandu et al. (2015), total scores on the NTB were 25% higher in the intervention group compared to the control group. In addition, sub-test performance was better for executive function (83% higher) and processing speed (150% higher) in the intervention group compared to controls. Fabre et al. (2002) found no improvements in global cognitive functioning, but found improvements for memory in the intervention groups. Small et al. (2006) found significant improvement in verbal fluency in the intervention group; however, there were no significant differences between the intervention and control groups in task-based cognitive measures. In the study by Forte et al. (2013), improvements in executive functioning were seen in single- and multi-component intervention groups, but the single-component group showed a greater overall improvement than the multi-component intervention group. In Oswald et al.'s study (2006), initial post-intervention analysis found the single-component cognitive training group and multi-component cognitive and physical training group to have improved cognitive performance, with the multi-component group showing the largest gains. However, after 5 years of follow up, only the multi-component group maintained these cognitive improvements.
Four studies (Fabre et al., 2002; Forte et al., 2013; Oswald et al., 2006; Small et al., 2006) were evaluated to be of poor or fair quality (Table 1). Limitations to these studies included a lack of clarity in outcome measures, participant characteristics, and findings, as well as short intervention periods and small samples. The remaining two studies (Clare et al., 2015; Ngandu et al., 2015) were of good quality because they included longer study durations with larger samples (12 months and N = 75, and 2 years plus 5-year follow up and N = 1,190, respectively), and blinding of participants and researchers.
Several single-component intervention reviews have examined improved cognitive functions, such as by cognitive training (Kelly et al., 2014), cognitive stimulation (Woods, Aguirre, Spector, & Orrell, 2012), and physical exercise (Young et al., 2015), and their results in terms of whether there was cognitive improvement and/or the levels of improvement varied. The results of the current review support the growing evidence suggesting that multi-component approaches may be more effective than single-component interventions at improving cognitive function and reducing the risk of cognitive decline in middle-aged and older adults (Bamidis et al., 2014; Williams, Plassman, Burke, Holsinger, & Benjamin, 2010). Although four of the six completed studies (Clare et al., 2015; Fabre et al., 2002; Ngandu et al., 2015; Oswald et al., 2006) included in the current review found multi-component interventions to have greater cognitive improvements than single-component or control conditions in showing better chances of maintaining cognitive health and delaying cognitive decline, most were of fair or poor quality (Forte et al., 2013; Oswald et al., 2006; Small et al., 2006).
Gaps in the research should be addressed in future studies. For example, although the IOM identified additional risk factors of cognitive decline (e.g., hypertension, diabetes, dietary habits, social isolation) (IOM et al., 2015), most of the reviewed studies targeted only physical activity and cognitive training domain as interventions (Clare et al., 2015; Fabre et al., 2002; Forte et al., 2013; Oswald et al., 2006). Only two studies (Ngandu et al., 2015; Small et al., 2006) examined the interventions for these risk factors. Small et al. (2006) provided a guidebook with nutritional advice and Ngandu et al. (2015) offered education on nutrition and metabolic/vascular risk factor reduction.
Four studies were included that are ongoing or whose results have not yet been published as indicators of the type of data that may be forthcoming (Table 2). The same inclusion criteria were used for the completed studies. Compared to the other six completed studies, all studies included samples of adults 65 or older with larger samples, ranging from 99 (O'Dwyer, Burton, Pachana, & Brown, 2007) to 3,533 (Richard et al., 2009) participants. Each study incorporated exercise as one of the intervention components. All studies included cognitive function as an outcome and used either the Mini-Mental State Examination and/or the Wechsler Memory Scale as outcome measurement tools. Richard et al. (2009) and Vellas et al. (2014) addressed vascular care and offered nutritional guidance; however, only Richard et al. (2009) examined social isolation as a risk factor. There is a lack of variation in risk factor targets, as well as a need for additional studies that specifically test multi-component approaches that target other risk factors identified in the IOM report, such as combinations of physical activity, diet, social interaction, and cardiometabolic medication management (IOM et al., 2015).
Overview of Multi-Component Intervention Trials With Results in Progress
The current review identified many limitations in the existing evidence base that can be rectified in future research investigations. Most studies had poor to fair quality based on the lack of blinding, non-existent or short-term follow up, and small samples. Furthermore, there were inconsistencies in cognitive domains measured, and a large range of instruments were used as measurement tools. The issue of variability in measurements due to lack of measurement standards made comparisons across studies difficult. There were approximately 30 different measurements used to evaluate cognitive outcomes, and the length of one half of the studies was ≤3 months (Fabre et al., 2002; Forte et al., 2013; Small et al., 2006). Identifying a key set of cognitive function measures could facilitate more rapid understanding of whether effects can be replicated and which domains of cognitive function are most improved by multi-component interventions. Use of a standardized test instrument would ensure that the results of the studies are due to differences in the interventions implemented and not caused by the measurement tool used. The National Institutes of Health Toolbox includes recommended tasks for neurological function, which covers domains of executive function, memory, and processing speed (Weintraub et al., 2014). Consistent use of this validated research test battery in future studies may address the disparities among measurement tools and improve research quality.
The strength and significance of the findings is unclear given the current evidence. Although all of the studies had significant improvement in at least one domain of cognitive function, overall they were of low quality. The lack of evaluation of long-term outcomes makes it difficult to assess whether such improvements could reduce the risk of cognitive decline. Longer-term studies are needed to examine the onset of dementia. Subjective assessments from participants were lacking in all studies. Including assessments of patient-reported cognitive symptoms could help determine whether the interventions change individuals' daily lives in meaningful ways. These changes could include functional ability as well as emotional and social aspects of patients' lives.
The current review builds on a previous review that identified the need for more multi-component intervention trials to examine effects on the cognitive health of older adults (Schneider & Yvon, 2013). The current review expanded on the quality assessment of studies and used a quality assessment tool in the data extraction process. The prior review also concluded that although the initial findings looked promising, no studies provided clear evidence of an improved effect on cognitive health.
The IOM report included some recommendations aimed at triggering further research and policy changes in this field (IOM et al., 2015). One recommendation addressing policy and nonpharmacological interventions states that the U.S. Food and Drug Administration (FDA) and Federal Trade Commission (FTC), as well as other relevant agencies, must ensure appropriate policy for interventions such as cognitive training, which maintain or enhance cognitive abilities (e.g., memory or attention). To determine which interventions should be implemented into policy, the IOM first recommends researching these interventions (IOM et al., 2015). Furthermore, agencies such as the FDA and FTC will not reimburse programs without quality evidence of improved cognitive outcomes. The current review summarized the state of the evidence to date but further work must be done before policies can be launched. Moreover, high-quality studies are required to provide sufficient evidence to make appropriate recommendations to individuals and policy makers.
Strengths and Limitations
There are several limitations to the current review. The authors were unable to complete a systematic review due to the wide variability in study interventions. Although this is a limitation, a quality assessment tool was used to evaluate the quality of evidence of each study, which is a strength. This assessment tool revealed that three studies were of fair quality, one was of poor quality, and only two were of good quality. The low-quality ratings indicate limitations in the existing evidence base that subsequently limited the ability of the reviewers to make definitive conclusions about the use of multi-component interventions on cognitive health.
The findings from the current review support the benefit of a multi-component approach over a single-component intervention. However, the quality of current evidence to evaluate the effect of multi-component interventions on the cognitive health of middle-aged and older adults is weak. Only six completed studies were identified in this scoping review, with an overall low quality of evidence. Varied measurement tools, small samples, short trial durations, and lack of follow-up trials make it difficult to determine the possible benefits of a multi-component approach over a single-component intervention. More rigorous randomized controlled trials are needed that include larger samples, longer intervention periods with more clearly defined interventions, and longer follow-up periods. Furthermore, a standardized measurement tool to evaluate cognitive outcomes, as well as a subjective assessment of participants, would also improve evidence quality. Additional high-quality studies will provide a better understanding of which factors, such as physical exercise, dietary habits, vascular risk factors, and cognitive training, protect the cognitive function of middle-aged and older adults and to what effect. This evidence can then inform the development of public health initiatives and evidence-based services to delay the onset of cognitive decline and promote the cognitive health of this vulnerable population.
- Arksey, H. & O'Malley, L. (2007). Scoping studies: Towards a methodological framework. International Journal of Social Research Methodology, 8, 19–32. doi:10.1080/1364557032000119616 [CrossRef]
- Bamidis, P.D., Vivas, A.B., Styliadis, C., Frantzidis, C., Klados, M., Schlee, W. & Papageorgiou, S.G. (2014). A review of physical and cognitive interventions in aging. Neuroscience and Biobehavioral Reviews, 44, 206–220. doi:10.1016/j.neubiorev.2014.03.019 [CrossRef]
- Barnes, D.E. & Yaffe, K. (2011). The projected effect of risk factor reduction on Alzheimer's disease prevalence. Lancet Neurology, 10, 819–828. doi:10.1016/S1474-4422(11)70072-2 [CrossRef]
- Clare, L., Nelis, S.M., Jones, I.R., Hindle, J.V., Thom, J.M., Nixon, J.A. & Whitaker, C.J. (2015). The Agewell trial: A pilot randomised controlled trial of a behaviour change intervention to promote healthy ageing and reduce risk of dementia in later life. BMC Psychiatry, 15, 25. doi:10.1186/s12888-015-0402-4 [CrossRef]
- Clark, P.G., Blissmer, B.J., Greene, G.W., Lees, F.D., Riebe, D.A. & Stamm, K.E. (2011). Maintaining exercise and healthful eating in older adults: The SENIOR project II: Study design and methodology. Contemporary Clinical Trials, 32, 129–139. doi:10.1016/j.cct.2010.10.002 [CrossRef]
- Downs, S.H. & Black, N. (1998). The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. Journal of Epidemiology and Community Health, 52, 377–384. doi:10.1136/jech.52.6.377 [CrossRef]
- Fabre, C., Chamari, K., Mucci, P., Massé-Biron, J. & Préfaut, C. (2002). Improvement of cognitive function by mental and/or individualized aerobic training in healthy elderly subjects. International Journal of Sports Medicine, 23, 415–421. doi:10.1055/s-2002-33735 [CrossRef]
- Forte, R., Boreham, C.A., Leite, J.C., De Vito, G., Brennan, L., Gibney, E.R. & Pesce, C. (2013). Enhancing cognitive functioning in the elderly: Multicomponent vs resistance training. Clinical Interventions in Aging, 8, 19–27. doi:10.2147/CIA.S36514 [CrossRef]
- Institute of Medicine, Board on Health Sciences Policy, & Committee on the Public Health Dimensions of Cognitive Aging. (2015). Cognitive aging: Progress in understanding and opportunities for action. Washington, DC: National Academies Press.
- Kelly, M.E., Loughrey, D., Lawlor, B.A., Robertson, I.H., Walsh, C. & Brennan, S. (2014). The impact of cognitive training and mental stimulation on cognitive and everyday functioning of healthy older adults: A systematic review and meta-analysis. Ageing Research Review, 15, 28–43. doi:10.1016/j.arr.2014.02.004 [CrossRef]
- Ngandu, T., Lehtisalo, J., Solomon, A., Levälahti, E., Ahtiluoto, S., Antikainen, R. & Kivipelto, M. (2015). A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): A randomised controlled trial. Lancet, 385, 2255–2263. doi:10.1016/S0140-6736(15)60461-5 [CrossRef]
- Norton, S., Matthews, F.E., Barnes, D.E., Yaffe, K. & Brayne, C. (2014). Potential for primary prevention of Alzheimer's disease: An analysis of population-based data. Lancet Neurology, 13, 788–794. doi:10.1016/S1474-4422(14)70136-X [CrossRef]
- O'Dwyer, S.T., Burton, N.W., Pachana, N.A. & Brown, W.J. (2007). Protocol for Fit Bodies, Fine Minds: A randomized controlled trial on the affect of exercise and cognitive training on cognitive functioning in older adults. BMC Geriatrics, 7, 23. doi:10.1186/1471-2318-7-23 [CrossRef]
- Oswald, W.D., Gunzelmann, T., Rupprecht, R. & Hagen, B. (2006). Differential effects of single versus combined cognitive and physical training with older adults: The SimA study in a 5-year perspective. European Journal of Ageing, 3, 179–192. doi:10.1007/s10433-006-0035-z [CrossRef]
- Papaioannou, D., Sutton, A. & Booth, A. (2012). Systematic approaches to a successful literature review. Los Angeles, CA: Sage.
- Plassman, B.L., Williams, J.W. Jr. , Burke, J.R., Holsinger, T. & Benjamin, S. (2010). Systematic review: Factors associated with risk for and possible prevention of cognitive decline in later life. Annals of Internal Medicine, 153, 182–193. doi:10.7326/0003-4819-153-3-201008030-00258 [CrossRef]
- Richard, E., Van den Heuvel, E., Moll van Charante, E.P., Achthoven, L., Vermeulen, M., Bindels, P.J. & Van Gool, W.A. (2009). Prevention of dementia by intensive vascular care (PreDIVA): A cluster-randomized trial in progress. Alzheimer Disease and Associated Disorders, 23, 198–204. doi:10.1097/WAD.0b013e31819783a4 [CrossRef]
- Schneider, N. & Yvon, C. (2013). A review of multidomain interventions to support healthy cognitive ageing. Journal of Nutrition, Health & Aging, 17, 252–257. doi:10.1007/s12603-012-0402-8 [CrossRef]
- Sindi, S., Mangialasche, F. & Kivipelto, M. (2015). Advances in the prevention of Alzheimer's disease. F1000Prime Rep, 7, 50. doi:10.12703/P7-50 [CrossRef]
- Sink, K.M., Espeland, M.A., Castro, C.M., Church, T., Cohen, R., Dodson, J.A. & Williamson, J.D. (2015). Effect of a 24-month physical activity intervention vs health education on cognitive outcomes in sedentary older adults: The LIFE randomized trial. Journal of the American Medical Association, 314, 781–790. doi:10.1001/jama.2015.9617 [CrossRef]
- Small, G.W., Silverman, D.H., Siddarth, P., Ercoli, L.M., Miller, K.J., Lavretsky, H. & Phelps, M.E. (2006). Effects of a 14-day healthy longevity lifestyle program on cognition and brain function. American Journal of Geriatric Psychiatry, 14, 538–545. doi:10.1097/01.JGP.0000219279.72210.ca [CrossRef]
- Vellas, B., Carrie, I., Gillette-Guyonnet, S., Touchon, J., Dantoine, T., Dartigues, J.F. & Andrieu, S. (2014). MAPT study: A multidomain approach for preventing Alzheimer's disease: Design and baseline data. Journal of Prevention of Alzheimer's Disease, 1, 13–22.
- Weintraub, S., Dikmen, S.S., Heaton, R.K., Tulsky, D.S., Zelazo, P.D., Slotkin, J. & Gershon, R. (2014). The cognition battery of the NIH toolbox for assessment of neurological and behavioral function: Validation in an adult sample. Journal of the International Neuropsychological Society, 20, 567–578. doi:10.1017/S1355617714000320 [CrossRef]
- Williams, J.W., Plassman, B.L., Burke, J., Holsinger, T. & Benjamin, S. (2010). Preventing Alzheimer's disease and cognitive decline. Retrieved from https://www.ahrq.gov/downloads/pub/evidence/pdf/alzheimers/alzcog.pdf
- Woods, B., Aguirre, E., Spector, A.E. & Orrell, M. (2012). Cognitive stimulation to improve cognitive functioning in people with dementia. Cochrane Database of Systematic Reviews, 2, CD005562. doi:10.1002/14651858.CD005562.pub2 [CrossRef]
- Young, J., Angevaren, M., Rusted, J. & Tabet, N. (2015). Aerobic exercise to improve cognitive function in older people without known cognitive impairment. Cochrane Database of Systematic Reviews, 4, CD005381. doi:10.1002/14651858.CD005381.pub4 [CrossRef]
Overview of Completed Multi-Domain Intervention Trials
|Study, Country||Design||Participants||Intervention||Study Length||Cognitive Outcome Measures||Results||Study Qualitya|
|Clare et al. (2015), North Wales||Pilot RCT||Healthy older adults (N = 75, 65% female)
Age (years): range = 51 to 84, mean (SD) = 68.21 (7.92)|
Goal setting (aimed at increasing cognitive and physical activity)
Multi-domain: goal setting with mentoring (aimed at increasing cognitive and physical activity)
|12 months||Primary: general cognition (FCAS)
Secondary: general cognition (MoCA), memory (CVLT), executive function (TMT, VFT)||All three groups improved in general cognitive ability (MoCA), verbal fluency (VFT), and immediate recall (CVLT). The greatest overall improvement with no significant findings was seen in the multi-domain intervention group.||Good|
|Fabre, Chamari, Mucci, Massé-Biron, & Préfaut (2002), France||RCT||Healthy older adults (N = 32, 84.4% female)
Age (years): range = 60 to 76|
Multi-domain (aerobic and cognitive training)
|2 months||General cognition (BEC-96), memory (WMS)||Memory was improved in the three intervention groups and significantly higher in the multi-domain group. No significant change in control group.||Poor|
|Forte et al. (2013), Italy||Randomized trial||Healthy older adults (N = 42, 62% female)
Age (years): mean (SD) = 69.8 (2.4)|
Multi-domain (MCT): physical exercise and cognitive challenges
|3 months||Executive function (RNG, TMT)||Both groups improved in executive function in both measures. The PRT group showed a greater improvement than the MCT group.||Fair|
|Ngandu et al. (2015), Finland||Multi-center, randomized, parallel-group, controlled trial||Older adults at risk for cognitive decline (N = 1,190, 46% female)
Intervention group (age [years]): mean (SD) = 69.5 (4.7)
Control group (age [years]): mean (SD) = 69.2 (4.7)|
Multi-domain (nutritional education, physical exercise, cognitive training, metabolic/vascular risk factor reduction)
|2 years and 5 years extended follow up||Primary: change in general cognitive performance (NTB total score)
Secondary: executive function (CF, DS, CST, TMT, Stroop test), processing speed (LDST, CST, Stroop test), memory (VisPa, Logical Memory immediate and delayed recall, WLL, delayed recall)||Significant improvement in cognitive performance, executive functioning, and processing speed in the intervention group.||Good|
|Oswald, Gunzelmann, Rupprecht, & Hagen (2006), Germany||RCT||Healthy older adults (N = 375, 64.8% female)
Age (years): range = 75 to 93, mean (SD) = 79.5 (3.5)|
Multi-domain (psychoeducational and physical training)
Multi-domain (cognitive and physical training)
|5 years||General cognitive function measured by composite score of: processing speed (NC-G, MT-G, DS-G), attention (Alters-Konzentrans Test, CWT-G), primary memory (MS-G, ST), secondary memory (PT, FT, WLL, WP), long-term memory (WAIS-Info, word fluency), and reasoning (WAIS-Sim)||At 1-year post- intervention, cognitive training and multi-domain groups had a significant improvement in composite cognitive function. The largest gains were seen in multi-domain cognitive and physical training groups. At 5 years, the multi-domain group achieved the largest number of sustained training gains.||Fair|
|Small et al. (2006), United States||RCT||Healthy adults (N = 17, 65% female)
Age (years): range = 35 to 69|
Multi-domain (lifestyle guidebook: nutritional advice, memory training, physical exercise plan, relaxation techniques)
|14 days||Memory (MFQ, VFT, Bushcke SRT)||The multi-domain group improved their verbal fluency, but improvement was not statistically significant for the control group.||Fair|
Overview of Multi-Component Intervention Trials With Results in Progressa
|Study, Country||Design||Participants||Intervention||Study Length||Cognitive Outcome Measures|
|O'Dwyer, Burton, Pachana, & Brown (2007), Australia||RCT||Healthy older adults (N = 99, age = 65 to 75 years)|
Multi-domain (cognitive training, physical exercise)
Physical exercise only
|4 months||Memory: logical memory and digit span subtests of the WMS-R
Executive functioning: COAST, MR
Mental speed: SRT, CRT, SDMT
|Clark et al. (2011), United States||RCT||Healthy older adults (N = 470, age = >65 years)|
Multi-domain (behavior manual, supervised goal-setting)
|4 years||Change in cognitive function: TMT, WMS|
|Vellas et al. (2014), France||Multi-center, randomized, placebo-controlled trial||Older adults at risk of cognitive decline (N = 1,680, age = ≥70 years)|
Multi-domain (vascular care, nutritional advice, physical training, social activities) and Omega-3 supplementation)
Placebo and multi-domain intervention
|3 years and 2 years extended follow up||Change in memory function: FCSRT
Cognition: COWA, CNT, DSST Subtest of WAIS, TMT, MMSE, CDR scale, and Alzheimer's disease biomarkers change|
|Richard et al. (2009), The Netherlands||Multi-center, cluster-randomized, parallel group controlled trial||Healthy older adults (N = 3,533, age = 70 to 80 years)|
Multi-domain (nurse-led vascular care: treatment of risk factors, nutritional guidance, exercise advice)
|6 years||Dementia and/or cognitive decline: ALDS
Cognitive functioning: MMSE, VAT|