Subtitle: Epidemiological Study with over 17,000 people in the Stroke belt; People with Diabetes Type II show different results

by Nancy Emerson Lombardo, Ph.D. © 2013

This is the largest study yet done on the Mediterranean diet, it focused on brain health and included many African Americans as well as Caucasians.

   Neurologist Georgios Tsivgoulis, MD, who is on the faculty at both University of Alabama and the University of Athens, in Athens, Greece, led this important     special purpose analysis of existing data in the REGARDS study at the University of Alabama, a study originally designed to assess risk factors for Stroke in the so  called “stroke belt” of the southern U.S. (REGARDS is a prospective, population-based, cohort of over 30,000 individuals age 45 and older, enrolled in the Reasons  for Geographic and Racial Differences in Stroke (REGARDS) Study 2003-2007). Dr Tsivgoulis excluded from the larger sample base, participants with history of stroke, impaired cognitive status at baseline, and/or missing data on Food Frequency Questionnaires (FFQ). The resulting number of people was 17,478 participants for his Med Diet study data base, with an average age of 64.  He applied the MeD diet strategy developed by another Greek MD working in the US, Nicholas Scarmeas MD who innovated the idea of applying a point system to be able to assess how closely any person’s food intake followed key elements of a Mediterranean style diet, regardless of their ethnicity or geography. People in the study were scored 0-9 points using data in their FFQ’s.

The REGARDS study did not use the same cognitive measures typical in other studies designed to assess Alzheimer’s risk, but did have a basic 6-point cognitive screen, with which his team to assess incident cognitive impairment (“ICI”), over a period of 4-5 years. This enabled the study to identify 1,248 (7%) of the study population who had developed cognitive impairment (ICI) during the study period.

The study found that in healthy people, those who more closely followed the Mediterranean diet were 19 percent less likely to develop problems with their cognition, i.e. thinking and memory skills. These key findings arevstated in abstract as:

“Higher adherence to MeD was associated with lower likelihood of ICI before (odds ratio OR 0.89; 95% confidence interval 0.79-1.00) and after adjustment for potential confounders (OR 0.87; 95% CI 0.76-1.00) including demographic characteristics, environmental factors, vascular risk factors, depressive symptoms, and self-reported health status.

Olive oil

Another very important finding was that race, whether people were African American or Caucasian, made no difference in these findings. But that the 17% of study participants with Diabetes Type II did
not show the same relationship between diet and developing cognitive impairment; their incidence of cognitive impairment was unrelated to diet. This is called an “interaction effect.”
Specifically, ” However, we identified a strong interaction of diabetes mellitus (p = 0.0134) on the relationship of adherence to MeD with ICI; high adherence to MeD was associated with a lower likelihood of ICI in nondiabetic participants (OR 0.81; 95% CI 0.70-0.94; p = 0.0066) but not in diabetic individuals (OR 1.27; 95% CI 0.95-1.71; p = 0.1063). “
Because the statistical significance of the odds ratio for diabetic individuals is greater than .05, the authors did not state that people with diabetes are MORE likely to develop cognitive impairment when they follow Mediterranean style food intake, although the trend suggests that may be the case.

 

Another researcher had an interesting comment on the study, also published in Neurology. Mr. William Grant at the Sunlight, Nutrition and Health Research Center suggests that we need to look at the genetic factors known from other studies to be related to both risk of Diabetes, and to risk of cognitive decline. ” Differences in the prevalence of apolipoprotein E (ApoE) alleles may explain this finding. The ApoE epsilon2 (ApoE2) allele is associated with increased risk of diabetes mellitus [2] while the ApoE4 allele is associated with increased risk of cognitive impairment and Alzheimer disease (AD). [3] There is also evidence that dietary effects on AD are affected by ApoE alleles. [4] While blacks have a higher prevalence of ApoE4 than whites or Hispanics, [5] the higher rate of diabetes associated with dietary factors may counter the effect of ApoE allele. It would be interesting in future studies to identify the components diet that affect risk of cognitive impairment as well as the interactions with genetic factors. ” http://www.neurology.org/

 

This important study is an epidemiological study, not a clinical trial such as the major Spanish study reported elsewhere. That is, it adds to the evidence base but is not a gold standard clinical trial as required to get our U.S. Center for Disease Control to add nutrition to its planned re-launch of the Healthy Brain Initiative. It is important though in adding to the impetus to get physicians and laypeople to recognize the importance of improved nutrition in protecting our brains! healthy plant foods

 

A bit of back-story from Dr. Nancy: I had the pleasure of being a reviewer for an earlier version of this manuscript, submitted over a year ago to another journal. I had suggested some revisions but urged its publication as offering unique database and perspectives; that journal ultimately rejected that version of the manuscript despite my urging its publication. I am thrilled that an even more prestigious journal has now published Dr. Tsivgoulis’s study.

 

Check out other reviews of this important article: medline plus

Also, don’t miss our earlier blog about the groundbreaking Spanish clinical trial of the Med Diet reporting dramatic decline in first time heart attacks and strokes in vulnerable older adults elsewhere on this website.  Heart and stroke health are closely related to brain health.

1.Tsivgoulis G, Judd S, Letter AJ, et al. Adherence to a Mediterranean diet and risk of incident cognitive impairment. Neurology 2013;80:1684- 1692. http://www.neurology.org/

2. Anthopoulos PG, Hamodrakas SJ, Bagos PG. Apolipoprotein E polymorphisms and type 2 diabetes: a meta-analysis of 30 studies including 5423 cases and 8197 controls. Mol Genet Metab 2010;100:283-291.

3. Sachdev PS, Lipnicki DM, Crawford J, et al. Risk profiles of subtypes of mild cognitive impairment: the Sydney memory and ageing study. J Am Geriatr Soc 2012;60:24-33.

4. Barberger-Gateau P, Lambert JC, Féart C, Pérès K, Ritchie K, et al. From genetics to dietetics: the contribution of epidemiology to understanding Alzheimer’s disease. J Alzheimers Dis 2013;33 Suppl 1:S457- S463.

5. Grant WB. A multicountry ecological study of risk-modifying factors for prostate cancer: Apolipoprotein E-4 as a risk factor and cereals as a risk reduction factor. Anticancer Res 2010.;30:189-199.

On April 30, 2013 Neurology published a major epidemiological study, the largest yet done featuring the Mediterranean Diet. This study focused on brain health and included many African Americans as well as Caucasians.

Neurologist Georgios Tsivgoulis, MD, who is on the faculty at both University of Alabama and the University of Athens, in Athens, Greece, led this important special purpose analysis of existing data in the REGARDS study at the University of Alabama, a study originally designed to assess risk factors for Stroke in the so called “stroke belt” of the southern U.S. (REGARDS is a prospective, population-based, cohort of over 30,000 individuals age 45 and older, enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study 2003-2007). Dr Tsivgoulis excluded from the larger sample base, participants with history of stroke, impaired cognitive status at baseline, and/or missing data on Food Frequency Questionnaires (FFQ). The resulting number of people was 17,478 participants for his Med Diet study data base, with an average age of 64.  He applied the MeD diet strategy developed by another Greek MD working in the US, Nicholas Scarmeas MD who innovated the idea of applying a point system to be able to assess how closely any person’s food intake followed key elements of a Mediterranean style diet, regardless of their ethnicity or geography. People in the study were scored 0-9 points using data in their FFQ’s.

 

The REGARDS study did not use the same cognitive measures typical in other studies designed to assess Alzheimer’s risk, but did have a basic 6-point cognitive screen, with which his team to assess incident cognitive impairment (“ICI”), over a period of 4-5 years. This enabled the study to identify 1,248 (7%) of the study population who had developed cognitive impairment (ICI) during the study period.

The study found that in healthy people, those who more closely followed the Mediterranean diet were 19 percent less likely to develop problems with their cognition, i.e. thinking and memory skills. These key findings arevstated in abstract as:

“Higher adherence to MeD was associated with lower likelihood of ICI before (odds ratio OR 0.89; 95% confidence interval 0.79-1.00) and after adjustment for potential confounders (OR 0.87; 95% CI 0.76-1.00) including demographic characteristics, environmental factors, vascular risk factors, depressive symptoms, and self-reported health status.

Olive oil

Another very important finding was that race, whether people were African American or Caucasian, made no difference in these findings. But that the 17% of study participants with Diabetes Type II did
not show the same relationship between diet and developing cognitive impairment; their incidence of cognitive impairment was unrelated to diet. This is called an “interaction effect.”
Specifically, ” However, we identified a strong interaction of diabetes mellitus (p = 0.0134) on the relationship of adherence to MeD with ICI; high adherence to MeD was associated with a lower likelihood of ICI in nondiabetic participants (OR 0.81; 95% CI 0.70-0.94; p = 0.0066) but not in diabetic individuals (OR 1.27; 95% CI 0.95-1.71; p = 0.1063). “
Because the statistical significance of the odds ratio for diabetic individuals is greater than .05, the authors did not state that people with diabetes are MORE likely to develop cognitive impairment when they follow Mediterranean style food intake, although the trend suggests that may be the case.

 

Another researcher had an interesting comment on the study, also published in Neurology. Mr. William Grant at the Sunlight, Nutrition and Health Research Center suggests that we need to look at the genetic factors known from other studies to be related to both risk of Diabetes, and to risk of cognitive decline. ” Differences in the prevalence of apolipoprotein E (ApoE) alleles may explain this finding. The ApoE epsilon2 (ApoE2) allele is associated with increased risk of diabetes mellitus [2] while the ApoE4 allele is associated with increased risk of cognitive impairment and Alzheimer disease (AD). [3] There is also evidence that dietary effects on AD are affected by ApoE alleles. [4] While blacks have a higher prevalence of ApoE4 than whites or Hispanics, [5] the higher rate of diabetes associated with dietary factors may counter the effect of ApoE allele. It would be interesting in future studies to identify the components diet that affect risk of cognitive impairment as well as the interactions with genetic factors. ” http://www.neurology.org/

 

This important study is an epidemiological study, not a clinical trial such as the major Spanish study reported elsewhere. That is, it adds to the evidence base but is not a gold standard clinical trial as required to get our U.S. Center for Disease Control to add nutrition to its planned re-launch of the Healthy Brain Initiative. It is important though in adding to the impetus to get physicians and laypeople to recognize the importance of improved nutrition in protecting our brains! healthy plant foods

 

A bit of back-story from Dr. Nancy: I had the pleasure of being a reviewer for an earlier version of this manuscript, submitted over a year ago to another journal. I had suggested some revisions but urged its publication as offering unique database and perspectives; that journal ultimately rejected that version of the manuscript despite my urging its publication. I am thrilled that an even more prestigious journal has now published Dr. Tsivgoulis’s study.

 

Check out other reviews of this important article: medline plus

 

1.Tsivgoulis G, Judd S, Letter AJ, et al. Adherence to a Mediterranean diet and risk of incident cognitive impairment. Neurology 2013;80:1684- 1692. http://www.neurology.org/

2. Anthopoulos PG, Hamodrakas SJ, Bagos PG. Apolipoprotein E polymorphisms and type 2 diabetes: a meta-analysis of 30 studies including 5423 cases and 8197 controls. Mol Genet Metab 2010;100:283-291.

3. Sachdev PS, Lipnicki DM, Crawford J, et al. Risk profiles of subtypes of mild cognitive impairment: the Sydney memory and ageing study. J Am Geriatr Soc 2012;60:24-33.

4. Barberger-Gateau P, Lambert JC, Féart C, Pérès K, Ritchie K, et al. From genetics to dietetics: the contribution of epidemiology to understanding Alzheimer’s disease. J Alzheimers Dis 2013;33 Suppl 1:S457- S463.

5. Grant WB. A multicountry ecological study of risk-modifying factors for prostate cancer: Apolipoprotein E-4 as a risk factor and cereals as a risk reduction factor. Anticancer Res 2010.;30:189-199.

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