To the Editor
Twenty five percent of older adults in the U.S. have type 2 diabetes, which increases their risk for cognitive decline.1, 2 This risk disproportionately affects African Americans because they have higher rates of diabetes than Whites and worse glycemic control, which magnifies their risk.3 These disparities contribute to why African Americans have twice the rate of Alzheimer’s disease as Whites.4 There are now 1 million older African Americans with diabetes in the U.S. and their number will double by 2030.5 This will multiply the burden of cognitive impairment in older African Americans and necessitates preventive interventions.
We are conducting an ongoing randomized controlled trial to test the efficacy of Behavioral Activation to reduce cognitive decline in African Americans with Mild Cognitive Impairment. Behavioral Activation is a standardized, evidence-based treatment that is often used to treat depression.6 We have uniquely applied this approach to increase participation in physical, cognitive, and social activities in order to preserve cognition. The attention control treatment is Supportive Therapy, which facilitates personal expression but contains no other active elements. Race-concordant community health workers deliver 6 in-home treatment sessions of both interventions. Because of our interest in diabetes and cognition, we examined treatment effects on the subgroup of participants with diabetes who have had 12 month assessments (n = 35).
Methods
At baseline and 12 months (masked to treatment assignment), we administered the Hopkins Verbal Learning Test-Revised Delayed Recall (HVLT) and the Uniform Data Set (UDS) Neuropsychological Battery, which includes tests assessing verbal memory, attention, semantic memory, language, processing speed, visuospatial ability, and executive function. Standardized z scores from the component UDS tests yield the UDS-Composite Score (UDS-CS), which reflects global cognition. Our pilot data indicate that a decrement of 0.45 UDS-CS points translates clinically to the inability to balance a checkbook, do laundry, shop, or prepare meals.
Results
The average age of participants was 75.1 years (SD 6.8); 28 (80%) were women. The Table shows that participants who received Behavioral Activation had improved scores over 12 months in 2 cognitive domains: episodic memory (HVLT score) and executive function/processing speed [Digit Symbol Substitution Test (DSST)]. Supportive Therapy controls had no comparable improvements. On the UDS-CS, a greater proportion of participants who received Behavioral Activation compared to Supportive Therapy improved by ≥ 0.45 points [40.0% vs. 21.1%; OR: 2.50 (.55 – 11.33)], and fewer declined by ≥ 0.45 points [6.7% vs. 21.1%; OR: 0.27 (.03 – 2.70)]. There were no significant changes in other neuropsychological test scores.
Table.
Cognitive Scores at Baseline and 12 Months by Treatment Group
| Behavioral Activation | Baseline | Month 12 | paired t | df | p-value |
|---|---|---|---|---|---|
| (n=16) | |||||
| HVLT * | 1.1 (1.7) | 2.9 (2.9) | −2.56 | 15 | .022 |
| DSST | 24.2 (11.7) | 29.6 (11.3) | −2.20 | 13 | .047 |
| Supportive Therapy | |||||
| (n=19) | |||||
| HVLT | 1.6 (2.0) | 2.6 (2.9) | −1.62 | 18 | .122 |
| DSST | 28.2 (11.5) | 28.8 (12.1) | −.38 | 15 | .708 |
HVLT = Hopkins Verbal Learning Test
DSST = Digit Symbol Substitution Test
mean; (SD); higher scores indicate better cognitive function.
Discussion
The treatment trends observed across three different cognitive measures in this sample of older African Americans with diabetes and Mild Cognitive Impairment suggest that Behavioral Activation may preserve cognition in this high risk group. The sample is small, however, and the analysis is underpowered to detect treatment group differences. Nevertheless, these preliminary findings concur with the results of previous studies indicating that physical, cognitive, and social activity may prevent cognitive decline, and extend these findings now to older African Americans with diabetes.7 The latter finding is important because the number and longevity of this population, and their risk for progressive cognitive decline and dementia, are increasing.
The Behavioral Activation treatment approach simultaneously targets two entrenched health problems in older African Americans (i.e., diabetes and impaired cognition), and may prevent cognitive decline by increasing cognitive (e.g., problem-solving) and physical (e.g., exercise) activities and perhaps by improving glycemic control. These two mechanisms are plausible because physical and cognitive inactivity, as well as poor glycemic control, increase the risk of cognitive decline.8,9 Because no disease-modifying treatment for Alzheimer’s disease now exists, if an early nonpharmacologic treatment like Behavioral Activation prevents cognitive decline even by one year, it will greatly reduce the personal and societal costs of Alzheimer’s disease in older African Americans.10
ACKNOWLEDGMENTS
This research is supported by grant 1R01AG035025 from the National Institute on Aging. ClinicalTrials.gov Identifier: NCT01299766
Footnotes
Conflict of Interest: The authors declare no competing interests.
Barry W. Rovner, MD and Robin J. Casten
Author Contributions
Barry W. Rovner, MD and Robin J. Casten: Study concept and design; analysis and interpretation of data; and preparation of the manuscript.
Sponsor’s Role: None.
REFERENCES
- 1.National Institute of Diabetes and Digestive and Kidney Diseases. National Diabetes Statistics fact sheet: General information and national estimates on diabetes in the United States. 2005 [Google Scholar]
- 2.Mayeda ER, Whitmer RA, Yaffe K. Diabetes and cognition. Clin Geriatr Med. 2015;31:101–115. doi: 10.1016/j.cger.2014.08.021. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes in African Americans. Bethesda, MD: U.S. Department of Health and Human Services, National Institutes of Health; 2005. 2005. NIH Publication No. 02-3266. [Google Scholar]
- 4.Alzheimer's Association. 2010 Alzheimer's disease facts and figures. Alzheimers Dement. 2010;6(2):158–194. doi: 10.1016/j.jalz.2010.01.009. PMID: 20298981. [DOI] [PubMed] [Google Scholar]
- 5.Administration on Aging. A statistical profile of black older Americans aged 65+ [Accessed August 1, 2013];2009 http://www.aoa.gov/Aging_Statistics/minority_aging/Facts-on-Black-Elderly-plain_format.aspx.
- 6.Kanter JW, Manos RC, Bowe WM, et al. What is behavioral activation? A review of the empirical literature. Clin Psychol Rev. 2010;30:608–620. doi: 10.1016/j.cpr.2010.04.001. [DOI] [PubMed] [Google Scholar]
- 7.Blazer DG, Yaffe K, Liverman CT, editors. Cognitive Aging: Progress in Understanding and Opportunities for Action. Washington, DC: National Academies Press; 2015. [Accessed April 14, 2015]. http://www.iom.edu/cognitiveaging. [PubMed] [Google Scholar]
- 8.Yaffe K, Falvey C, Hamilton N, et al. Diabetes, glucose control, and 9-year cognitive decline among older adults without dementia. Arch Neurol. 2012;69:1170–1175. doi: 10.1001/archneurol.2012.1117. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Macauley SL, Stanley M, Caesar EE, et al. Hyperglycemia modulates extracellular amyloid-β concentrations and neuronal activity in vivo. J Clin Invest. 2015;125:2463–2467. doi: 10.1172/JCI79742. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Brookmeyer R, Evans DA, Hebert L, et al. National estimates of the prevalence of Alzheimer's disease in the United States. Alzheimers Dement. 2011;7:61–73. doi: 10.1016/j.jalz.2010.11.007. [DOI] [PMC free article] [PubMed] [Google Scholar]