FW: NATAP: Mediterrean Diet Protects Brain/Reduce Stroke-Memory Loss

[Le-Ann Dolan]

Via Ron Rosenes

Le-Ann

 

Canadian Working Group on HIV and Rehabilitation

600 - 1240 Bay Street

Toronto, Ontario

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Fax: 416-595-0094

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From: Ronald Rosenes [mailto:r...@rosenes.com]
Sent: February 28, 2012 3:05 PM
To: Le-Ann Dolan; Leah Stephenson
Subject: Fwd: NATAP: Mediterrean Diet Protects Brain/Reduce Stroke-Memory Loss

 

 

 

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Date:

February 15, 2012 7:34:43 AM EST

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"H...@natap.org natap" <h...@natap.org>

Subject: NATAP: Mediterrean Diet Protects Brain/Reduce Stroke-Memory Loss

NATAP http://natap.org/
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Mediterranean Diet and White Matter Hyperintensity Volume in the Northern Manhattan Study - pdf attached

 

Arch Neurol. Feb 2012

Hannah Gardener, ScD; Nikolaos Scarmeas, MD, MS; Yian Gu, PhD; Bernadette Boden-Albala, MPH, DrPh;

Mitchell S. V. Elkind, MD, MS; Ralph L. Sacco, MD, MS; Charles DeCarli, MD; Clinton B. Wright, MD, MS

Univ of Miami, Columbia Univ NYC et al

 

 

 

"In summary, the current study suggests a possible protective association between increased consumption of a MeDi (Mediterranean Diet) and small vessel disease.....diet might protect against blood-vessel damage in the brain, reducing the risks of stroke and memory loss'. The MeDi emphasizes a high consumption of olive oil, plant proteins, whole grain, and fish; a moderate consumption of alcohol; and a low consumption of red meat, refined grains, and sweets. The associations with WMHV may be driven by the favorable ratio of monounsaturated fat consumption over saturated fat. However, the results of the analysis of the individual MeDi scale components suggest that the overall dietary pattern, rather than any of the individual components, may be more etiologically relevant in relation to WMHV. Future studies are necessary to replicate and further explore the nature of the association between a MeDi and WMHV"...."It's the first study to specifically examine the effects of the diet centered around vegetables, fruits, fish, whole grains, nuts, olive oil and a moderate amount of alcohol, with limited consumption of red meat, sweets and refined grains like white bread or white rice—on the brain's small blood vessels.....Previous studies have suggested adhering to a Mediterranean-style diet is associated with a lower risk of heart disease, stroke and cognitive disorders like Alzheimer's disease. In the latest study, researchers, led by a group at the University of Miami in Florida and Columbia University in New York, analyzed food questionnaires filled out by nearly 1,000 people participating in a larger, ongoing Northern Manhattan Study. These participants were categorized into groups based on how closely they adhered to an ideal Mediterranean-style diet, said Clinton Wright, one of the researchers and an associate professor of neurology at Miami's Miller School of Medicine. Researchers then used magnetic resonance imaging, or MRI, scans of the brain to look for what are called white matter hyperintensities, which show up as small lesions on the scan and indicate damage to small blood vessels. The damaged blood vessels can cause small so-called silent strokes with no immediate symptoms but which over time can affect cognitive performance. Broadly, the study showed that people with the highest Mediterranean diet scores had the lowest white-matter volume burden. Researchers also found that the type of fat appeared to matter. Those who consumed more monounsaturated fat, which is found in olive oil, had lower white-matter hyperintensity volumes on their brain scans. Dr. Wright cautioned that the study doesn't prove that a Mediterranean-style diet causes less brain damage and said more study is needed. But he said it indicates that the diet might be protective of small blood vessels in the brain." Wall St Jnl 

 

"our findings add to a growing body of literature indicating that a MeDi may be protective against subclinical vascular damage......The results of the current study link a MeDi with a lower burden of WMHV (a marker of small vessel damage in the brain) and suggest a possible mechanism to explain studies showing that a MeDi is protective against overall mortality and death due to cardiovascular disease.⁶ Furthermore, consumption of a MeDi has been associated with a lower risk of mild cognitive impairment, Alzheimer disease, and dementia, and there is great interest in small vessel damage in these processes as well. To our knowledge, this is the first study to examine the

association between the MeDi and brain WMHV"

 

"Our finding of a lower WMH burden among those with greater consumption of a MeDi are consistent with previous studies that have shown inverse associations between adherence to the MeDi and several subclinical markers of vascular disease risk. The MeDi has been associated with improved endothelial function,²³ adiposity,²⁴ and lower levels of inflammatory markers, including C-reactive protein²⁵ and interleukin 6,²⁶ and these may be mechanisms underlying the observed association between the MeDi and WMHV."

 

"White matter hyperintensities (WMHs) visible on T2-weighted magnetic resonance imaging (MRI) are markers of chronic small vessel damage. Although they are often seen in people who are aging normally, WMHs are associated with vascular risk factors, including smoking, diabetes mellitus, high blood pressure, and dyslipidemia; correlate with small vessel damage in other organs, such as the eye and kidney; and can predict an increased risk of stroke and dementia (when a heavy burden is present)

The results of the current study link a MeDi with a lower burden of WMHV (a marker of small vessel damage in the brain) and suggest a possible mechanism to explain studies showing that a MeDi is protective against overall mortality and death due to cardiovascular disease.⁶ Furthermore, consumption of a MeDi has been associated with a lower risk of mild cognitive impairment, Alzheimer disease, and dementia, and there is great interest in small vessel damage in these processes as well.^7-9 Although replication of these findings in other cohorts, as well as prospective imaging studies, are needed, our findings add to a growing body of literature indicating that a MeDi may be protective against subclinical vascular damage."

ABSTRACT

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Objective  To examine the association between a Mediterranean-style diet (MeDi) and brain magnetic resonance imaging white matter hyperintensity volume (WMHV).

Design  A cross-sectional analysis within a longitudinal population-based cohort study. A semiquantitative food frequency questionnaire was administered, and a score (range, 0-9) was calculated to reflect increasing similarity to the MeDi pattern.

Setting  The Northern Manhattan Study.

Participants  A total of 1091 participants, of whom 966 had dietary information (mean age, 72 years; 59.3% women, 64.6% Hispanic, 15.6% white, and 17.5% black).

Main Outcome Measures  The WMHV was measured by quantitative brain magnetic resonance imaging. Linear regression models were constructed to examine the association between the MeDi score and the log-transformed WMHV as a proportion of total cranial volume, controlling for sociodemographic and vascular risk factors.

Results  On the MeDi scale, 11.6% scored 0 to 2, 15.8% scored 3, 23.0% scored 4, 23.5% scored 5, and 26.1% scored 6 to 9. Each 1-point increase in MeDi score was associated with a lower log WMHV (β = –.04, P = .01). The only MeDi score component that was an independent predictor of WMHV was the ratio of monounsaturated to saturated fat (β = –.20, P = .001).

Conclusions  A MeDi was associated with a lower WMHV burden, a marker of small vessel damage in the brain. However, white matter hyperintensities are etiologically heterogenous and can include neurodegeneration. Replication by other population-based studies is needed.

INTRODUCTION

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White matter hyperintensities (WMHs) visible on T2-weighted magnetic resonance imaging (MRI) are markers of chronic small vessel damage. Although they are often seen in people who are aging normally, WMHs are associated with vascular risk factors, including smoking, diabetes mellitus, high blood pressure, and dyslipidemia; correlate with small vessel damage in other organs, such as the eye and kidney; and can predict an increased risk of stroke and dementia (when a heavy burden is present).^1-4

Although diet may be an important predictor of vascular disease, little is known about the possible association between dietary habits and WMHs. The Mediterranean-style diet (MeDi), representing the typical dietary habits of the populations bordering the Mediterranean Sea, includes a relatively high intake of fruits, vegetables, monounsaturated fat, fish, whole grains, legumes, and nuts; moderate alcohol consumption; and a low intake of red meat, saturated fat, and refined grains.

Studies have suggested that consumption of a MeDi is associated with a reduced risk of the metabolic syndrome,⁵ coronary heart disease,⁶ stroke,⁶ and cognitive disorders,^7-9 but no studies to date, to our knowledge, have examined the association between a MeDi and WMH volume (WMHV). A greater understanding of modifiable risk factors for small vessel damage may facilitate the prevention of both stroke and cognitive decline. The previously observed associations between the MeDi and vascular risk factors and vascular outcomes–in addition to studies showing that 2 components of a MeDi, moderate alcohol use and fish consumption, are inversely associated with white matter abnormalities^10-12 –suggest the importance of examining the potential association between a MeDi and WMHV. Therefore, the goals of the current study are to examine the association between consumption of a MeDi and brain WMHV in a large, multiethnic, population-based cohort and to examine the potential moderating effects of known vascular risk factors, including age, blood pressure, diabetes, and lipid profiles.

COMMENT

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The results of this study suggest a lower burden of WMHV among those with greater consumption of a MeDi. The association between a MeDi and WMHV was independent of sociodemographic and vascular risk factors, including physical activity, smoking, blood lipid levels, hypertension, diabetes, history of cardiac disease, and BMI. In particular, the data suggest that the most important component of the MeDi in predicting WMHV may be the ratio of monounsaturated to saturated fat. These findings indicate a potential role of dietary factors in small vessel disease.

To our knowledge, this is the first study to examine the association between the MeDi and brain WMHV. In fact, we found no previous studies examining the potential association between overall dietary patterns and WMHV. Previous studies^10-12 have shown a protective effect of moderate fish intake and moderate alcohol consumption on MRI white matter abnormalities. However, these components of the MeDi score were not significant independent predictors of WMHV in the current study. Vitamin D deficiency and low serum folate levels have also been associated with increased WMHV in previous studies.^21-22

Our finding of a lower WMH burden among those with greater consumption of a MeDi are consistent with previous studies that have shown inverse associations between adherence to the MeDi and several subclinical markers of vascular disease risk. The MeDi has been associated with improved endothelial function,²³ adiposity,²⁴ and lower levels of inflammatory markers, including C-reactive protein²⁵ and interleukin 6,²⁶ and these may be mechanisms underlying the observed association between the MeDi and WMHV.

The results of the current study link a MeDi with a lower burden of WMHV (a marker of small vessel damage in the brain) and suggest a possible mechanism to explain studies showing that a MeDi is protective against overall mortality and death due to cardiovascular disease.⁶ Furthermore, consumption of a MeDi has been associated with a lower risk of mild cognitive impairment, Alzheimer disease, and dementia, and there is great interest in small vessel damage in these processes as well.^7-9 Although replication of these findings in other cohorts, as well as prospective imaging studies, are needed, our findings add to a growing body of literature indicating that a MeDi may be protective against subclinical vascular damage.

Roughly half of the NOMAS participants self-identified as Hispanic, and most immigrated to the United States from the Dominican Republic in the Caribbean. Several studies^27-30 have demonstrated beneficial health effects of a MeDi in non-Mediterranean populations, supporting the importance of examining the association between a MeDi and subclinical vascular disease in our non-Mediterranean and multiethnic population in Northern Manhattan. As a whole, the dietary habits of the NOMAS cohort at baseline were less consistent with a MeDi pattern compared with other European (Greek³¹ and Spanish³²) and US^{6, 30} cohort studies in which the MeDi has been examined. In particular, the consumption of fruits, vegetables, legumes, fish, and cereals was less in our cohort than in others.^{6, 30-32} Therefore, the diet patterns of the NOMAS cohort may not accurately reflect a true MeDi (ie, similar to that followed by populations in the Mediterranean region). For example, consumption of monounsaturated fatty acids, mostly deriving from olive oil, is considerably lower in our population compared with Mediterranean ones. In this context, the results of the current study imply that even a modest adherence to a MeDi (compared with those whose dietary habits are even farther away from the MeDi principles) may protect against vascular outcomes. Similarly, the fact that the ratio of monounsaturated fatty acids to saturated fatty acids was significantly associated with WMHV, despite the low level of olive oil use, only underscores its importance because it implies that even low consumption of olive oil has the potential to be etiologically relevant.

Strengths of our study include the large, ethnically diverse, population-based cohort of both middle-aged and elderly adults and the comprehensive data on other established vascular risk factors. However, our study has several limitations. We only measured food frequency at baseline, which was on average 7 years before the time of MRI WMH assessment (range, 2-14 years), and thus participants could have changed their diet before the MRI was performed. However, dietary patterns appear to be stable in other population-based studies.³³ In addition, despite the use of a valid and reliable food frequency questionnaire^{19, 34-35} to calculate MeDi scores, a potential for both random and systematic misclassification of dietary habits persists, although any misclassification is most likely to be random and thus tending to minimize an association between a MeDi and WMHV. Most studies depend on similar methods, and they are a practical approach, albeit subjective in nature. In addition, we used the traditional MeDi score method to quantify adherence, but this too has limitations because the score is based on the cohort- and sex-specific median values across 9 food categories, which does not readily allow for an examination of dose-dependent associations. However, most population-based studies have used this approach. Although the potential for confounding always exists, the persistence of associations after adjustment for many potential confounders suggests that this form of bias does not account for the associations observed. The MRI study population represents a subcohort of the overall NOMAS cohort and was younger and generally healthier than the full cohort. However, as mentioned previously, we did not observe diet differences between those who were included and excluded, again suggesting that selection into the study cohort did not bias our results. Last, MRIs to measure WMHV were only conducted once, so we are unable to infer the temporal association between the MeDi and development of WMHs.

In summary, the current study suggests a possible protective association between increased consumption of a MeDi and small vessel disease. The MeDi emphasizes a high consumption of olive oil, plant proteins, whole grain, and fish; a moderate consumption of alcohol; and a low consumption of red meat, refined grains, and sweets. The associations with WMHV may be driven by the favorable ratio of monounsaturated fat consumption over saturated fat. However, the results of the analysis of the individual MeDi scale components suggest that the overall dietary pattern, rather than any of the individual components, may be more etiologically relevant in relation to WMHV. Future studies are necessary to replicate and further explore the nature of the association between a MeDi and WMHV.

RESULTS

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