LOS ANGELES — Stroke patients may help prevent cognitive decline by following a low-salt diet rich in foods such as green leafy vegetables and berries, a new study suggests.
The diet studied in this analysis is the so-called Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet, a hybrid of the low-sodium DASH (Dietary Approaches to Stop Hypertension) diet and the Mediterranean diet that focuses on fruits, vegetables, whole grains, and lean protein.
Previous studies have shown the MIND diet to be associated with slower cognitive decline in healthy older people. The results from this new analysis indicate that stroke survivors might derive even more benefit from this diet than the general population does.
In addition to receiving standard care, such as getting a statin and blood pressure medication, counseling on smoking cessation and compliance, and undergoing neurologic exams, stroke survivors may benefit from the input of a dietitian and meal planning, said study author Laurel J. Cherian, MD, vascular neurologist and assistant professor of neurological sciences, Rush University Medical Center, Chicago, Illinois.
“Perhaps there are not enough resources devoted to diet” in this population, she said.
The study was presented here at the International Stroke Conference (ISC) 2018.
Americans “are falling far short” of dietary recommendations, Dr Cherian told a media briefing here. For example, they’re not eating enough vegetables, fruits, and whole grains and are consuming too much sugar, saturated fats, and salt.
There’s a “clear regional variation” across the United States in terms of stroke rates and deaths, said Dr Cherian. These tend to be higher in areas that have traditionally had higher-fat/higher-salt diets, “so we know diet plays a role,” she said.
Double the Dementia Rate
Stroke survivors have almost double the rate of dementia than the general population. Compared to the rate of neuron loss that occurs with normal aging, ischemic stroke causes 3.6 years’ worth of aging for every hour of untreated stroke symptoms.
“So the brain may age a decade or more with a single episode,” said Dr Cherian.
The risks are highest for patients with a low level of education, those with cortical infarcts, and those with multiple strokes, she added. Data from the Framingham study suggest that almost 20% of stroke survivors develop dementia within 10 years of their stroke.
At the same time, mounting evidence points to the importance of diet in preserving cardiovascular health. For example, the Nurses’ Health Study and the Framingham Study showed that diet is important for primary stroke prevention, and some studies suggest that diet is important for secondary stroke prevention, the authors note.
In addition, there’s evidence that diet may help prevent dementia. Studies have shown a protective effect on cognition, for example, with adherence to the Mediterranean and the DASH diets.
Previous results from the Rush Memory and Aging Project (MAP) study, which looked at dietary habits of older Chicago residents without dementia, and followed these participants for an average of 4.5 years, showed that those who were the most adherent to the MIND diet functioned as if they were 7.5 years younger than those who were the least adherent.
The MIND diet recommends at least three servings of whole grains a day and six servings of green leafy vegetables and two servings of berries a week, and it encourages regular consumption of other vegetables, fish, poultry, beans, and nuts. As well, it recommends olive oil as the primary oil and alcohol once per day. The diet restricts intake of red meats, fast foods, cheese, desserts, and butter.
For the present analysis, Dr Cherian and her team wanted to look at diet and rate of cognitive decline in stroke survivors. They found 106 such people in the MAP and put them through a model assessing cognitive decline over time.
The mean age of this study population was 82.8 years; 27.4% were male.
The analysis used food-frequency questionnaires to assess how closely participants adhered to the DASH diet, the Mediterranean diet, and MIND diet. Participants had annual cognitive assessments, which included a battery of 19 cognitive tests that were scored for a global cognitive variable.
Researchers adjusted for factors known to increase risk for dementia, including age, sex, level of education, APOE4 status, caloric intake, smoking history, cognitive activity, and level of physical activity.
The researchers found the top tertile for MIND diet scores vs the lowest tertile was significantly associated with slower decline in two cognitive domains: global cognition (β = 0.083; confidence interval [CI] = 0.007 – 0.158) and semantic memory (β = 0.070; CI, 0.001 – 0.138; P = .043).
Perceptual speed also improved (β = 0.071; CI = 0.000 – 0.142; P = .059).
Dr Cherian noted that these results for stroke patients were stronger than for the general population: While in the MAP study overall, highest adherents tested as if they were 7.5 years younger than the least adherent participants; here the difference was more like 20 years younger in terms of functioning, she said.
“This means that stroke survivors, although they have double the risk of developing dementia, if they make healthy changes, this diet and this pattern of eating may be doubly effective for them.”
Preserving cognitive ability is a “key factor” contributing to quality of life and ability to live independently, she noted.
Patients don’t have to be strict about sticking to the diet. Stroke patients who were only moderately adherent to the MIND diet also benefited in terms of cognition, the study found.
“There was a trend that showed that even if you didn’t follow this diet perfectly, if you just made some of these healthy changes, you were better off than the least adherent group,” said Dr Cherian.
Following the DASH or Mediterranean diets, which has been shown to protect against myocardial infarction and stroke, and possibly also have a cognitive benefit, did not significantly protect cognition in this analysis. However, a larger study may have found these diets to be protective, said Dr Cherian.
“It seems to be that some of the elements of the MIND diet are particularly good for brain health.”
Antioxidant Effect
Dr Cherian believes that these elements include antioxidants found in fruits such as blueberries and raspberries and in green leafy vegetables, including spinach and kale, as well as “good” fats.
“The science on this has evolved over time; it’s not necessarily how much or how little fat we’re getting, but the quality of the fat,” said Dr Cherian.
This means forgoing trans fats and hydrogenated fats in favor of “high nutrient density fats,” such as fish oils (eg, omega 3 and omega 6, including linoleic acid), she said.
“It’s sort of supercharging the ingredients that the brain needs to maintain proper brain health.”
Dr Cherian said she would like to see a dietary expert incorporated “in a formal way” into the team overseeing care for stroke patients.
As well, she said, a dietary intervention trial is warranted to validate the role of diet in long-term outcomes for stroke survivors.
A dietary intervention “is something every stroke patient can and I think should be doing, and I’d love to see that studied in a formal randomized clinical trial.”
Food and nutrition “can be viewed as one of the most powerful tools in our arsenal, not only for stroke prevention but also for preventing cognitive decline and dementia after a stroke,” said Dr Cherian.
For a lot of patients, experiencing a stroke is “a wake-up call” to start making healthy lifestyle choices, she said. She recommends including the family in nutrition counseling for stroke patients.
In an interview with Medscape Medical News, Philip B. Gorelick, MD, chief medical officer, Thorek Memorial Hospital, Chicago, who chaired the media briefing, said that these findings provide evidence that by adhering to the MIND diet, patients can “maintain cognitive vitality.”
However, he cautioned that the data are from a small subset of patients and need to be validated in a much larger study.
The medical profession is now “at a crucial point” in terms of being educated themselves about nutrition and counseling patients about the role of diet, said Dr Gorelick.
“Dietary factors are playing such an important role in cardiovascular diseases and in the maintenance of cognitive vitality that we need to seriously consider how we’re educating our doctors and/or the necessity of bringing in dietitians who understand this area to help us in an interdisciplinary or multidisciplinary approach,” he added.
The National Institute on Aging provided funding for the study.
International Stroke Conference (ISC) 2018. Late-breaking abstract 152. Presented January 25, 2018.
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