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Can Alzheimer’s Disease Be Prevented?

Rich — Fri, 19 Jan 2018 02:23:02 +0000

Many of us think that Alzheimer’s disease (AD) and age-related dementia (ARD) are unavoidable facts of life, things that we just have to accept and live with. But a growing number of studies suggest that making healthy lifestyle changes can be a powerful way to not only improve overall health, but also prevent and treat memory loss. Best of all, researchers say that it’s never too late to make changes that can help protect your brain and body health for years to come (Baumbart et al., 2015). This blog will study four of the most popular diets used to improve cognitive function in people of all ages. Later on, we’ll consider how different cooking methods can affect the nutritional value of food. We’ll also look into the effects of exercise, socialization and mental training on the brain.

But first, eating a healthy diet is one of the most effective, not to mention enjoyable, ways to fight cognitive decline. Scientific evidence suggests that a healthy diet protects both the heart and the head. And, who doesn’t like eating great tasting food that makes you feel better? Researchers have found that many cardiovascular diseases such as high blood pressure, diabetes and high cholesterol also increase the risk of developing Alzheimer’s and age-related dementia. One recent study shows that as many as 80 percent of people with AD also have cardiovascular disease (Baumgart et al., 2015).

Additionally, several studies have found that a brain-friendly diet helps control and regulate excess insulin in the bloodstream. Insulin accelerates neurodegenerative decay by damaging insulin receptors and destroying pro-inflammatory molecules that help protect the brain by stifling the buildup of beta amyloid plaques (Krikorian et al., 2012). Amyloid plaques can cause extensive and devastating neuronal destruction. Scientists don’t yet know what causes these harmful plaques to form, but have long suspected them to be leading causes of AD and dementia. Magee (2010), says a steady diet of antioxidants found in foods such as blueberries, nuts and dark green vegetables help reduce inflammation and oxidative stress. Inflammation is thought to be an underlying cause of AD and ARD (Nield, 2016).

Chronic levels of inflammation surround amyloid plaque buildups are one of the most common and easily recognizable features of AD and ARD. Researchers say a brain healthy diet can help reduce these levels of cerebral inflammation in both healthy people and those already suffering from AD and dementia. High levels of saturated fats are also being called a possible cause of AD and ARD (Morris, 2009). Researchers say these bad fats increase cholesterol levels, which encourages the growth of amyloid plaques in the brain. Another theory suggests that a poor diet can lead to an excessive buildup of an amino acid called homocysteine (Morris, 2003). Homocysteine is often found in high levels in people suffering from AD and ARD. Researchers say large buildups of homocysteine might stimulate a buildup of beta amyloid plaques and inhibit the brain’s ability to repair brain cells.

The Respite House blog will concentrate on four diets that have been extensively studied and found to improve cognitive function: the Mediterranean diet, the DASH (Dietary Approaches to Stop Hypertension) diet, the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diet, and the Ketogenic diet. The Mediterranean diet focuses on foods high in monounsaturated fatty acids found in olive oil and omega-3 fatty acids found in fish, nuts, fresh fruits and green vegetables (Scarmeas, 2006). The DASH diet was developed to control high blood pressure, which is a well-known risk factor for AD (Smith et al., 2010). The MIND diet combines elements of the Mediterranean diet and DASH diet and was developed specifically to battle dementia (Marcason, 2015). And finally, the ketogenic diet is a high-fat, low-carbohydrate diet that provides the brain with an alternative fuel source. Studies show it might help slow or even reverse memory loss and cognitive impairment (Eenfeldt, 2017).

It should be noted that eating a healthy diet is only part of a well-designed strategy to delay or prevent Alzheimer’s and dementia. Researchers at the Kansas University Alzheimer’s Disease Center, one of 29 National Institute of Health funded Alzheimer’s centers, think that Alzheimer’s and age-related dementia are caused by a slow down in brain cell metabolism at the molecular level. And that this slow down starts 20 years or more before the first symptoms finally surface. Two of the most efficient and natural ways to increase are metabolisms are diet and exercise. So, in addition to following a healthy diet, exercise for four or five days a week is also recommended. Regular social interaction is also critical to maintaining brainpower. Doctors and researchers also urge older adults to keep their brains active with games, learning new skills, and other lifelong learning pursuits. We’ll get to all of this. But first, in our next post, let’s take a look a one of the most popular and brain-healthy diets on the planet. The Mediterranean diet.

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The DASH Diet may help prevent Alzheimer’s

Rich — Wed, 17 Jan 2018 07:39:10 +0000

Another popular diet that’s shown promising results in reducing the risk of developing Alzheimer’s disease (AD) and other age-related dementias is the DASH diet. DASH stands for “Dietary Approaches to Stop Hypertension.” The diet was created by doctors 25 years ago to help treat or prevent high blood pressure. While the DASH diet does a great job of lowering blood pressure, several studies have found that it is also good for the brain. Older adults with high blood pressure have a much greater risk for cognitive decline, AD, and vascular dementia. In fact, high blood pressure affects more than half of all adults ages 60 years or older (Smith et al., 2010).

The DASH diet was designed to lower sodium intake. The average American’s diet contains some 3,400 mg of sodium a day. There are two versions of the DASH diet. The original diet allows up to 2,300 mg of sodium a day. A revised diet reduces sodium for people with hypertension to only 1,500 mg a day (Heller, 2016). Both DASH diets emphasize eating vegetables, fruits, and low-fat dairy. DASH dieters can eat moderate amounts of whole grains, fish, poultry, and nuts. Lean red meat, sweets, and fats are allowed, but only in small amounts.

To assess the cognitive benefits of the DASH diet Smith et al. (2010), recruited 124 participants with elevated blood pressure who were sedentary and had body mass indexes between 25 and 44. Participants were randomly assigned to three groups for the four-month study; a DASH diet but no exercise group, a DASH diet plus exercise group, and a control group that didn’t exercise or follow the DASH diet.

The DASH diet only group were shown how to modify their diet but received no exercise encouragement or instructions. The DASH diet plus exercise group was given the same dietary advice but also attended three 30-minute aerobic exercise programs per week in addition to a weekly half-hour group counseling session that focused on weight loss. The control group did not amend their diet or exercise routines.

To assess physiological changes, researchers took high-resolution ultrasound images of the participant’s brains at baseline and again after the four month intervention to measure common carotid arteries. Common carotid arteries are jugular arteries that supply oxygenated blood to the head and neck. To measure any cognitive performance changes, study subjects were given several neurocognitive tests at baseline and again four months later to assess executive function, memory, and psychomotor speed.

Researchers found the DASH diet plus exercise group experienced significant improvements in neurocognitive function compared to the sedentary control group. The DASH diet plus exercise group scored an impressive 6.1-year improvement on the four-month follow-up test that measured the time it took them to identify and differentiate colors and words from a list. Conversely, the sedentary control group scored an 11.7-year poorer performance on the same test. Similar gains were found on the follow-up psychomotor speed test with both the DASH plus exercise and the DASH alone groups relative to the control group. In addition, participants in both active treatment groups had lower blood pressure than the control group.

The biggest shortcoming of the Smith et al. study was it’s short four-month time frame. Researchers say they don’t know whether the benefits of the DASH diet plus exercise and DASH diet alone groups are temporary, or are things that can be maintained over time. The study does not reveal the underlying physiological mechanisms that improved cognitive function. Researchers also note that cognitive gains could be caused by a reduction in inflammation and other unknown neurochemical changes.

Both the DASH diet and the Mediterranean diet are very similar. Both are based on heart-healthy eating habits that emphasize natural, unprocessed foods. Both are rich in fruits and vegetables, whole grains, legumes and nuts. Both diets encourage eating unsaturated fats, while saturated fats, sugar, and empty calories are strongly discouraged. Both diets are also relatively flexible. Finally, both promote long-term lifestyle changes rather than short-term fixes or dietary fads.

The main differences between the DASH diet and Mediterranean diet is that the DASH diet is more structured and emphasizes portion control and calorie restrictions, where as the Mediterranean diet doesn’t mention portion size or recommend specific amounts of any food group (Özkurt, 2015). Both diets limit saturated fat intake, but the Mediterranean diet’s focus on olive oil means that it is more likely to be a high fat and calorie diet. It’s also possible that the Mediterranean diet may be more heart-healthy due to the fact that it’s cholesterol-lowering properties.

Another important difference between the two diets is the DASH diet allows for two to four servings of dairy products each day. Given the scarcity of dairy products in many parts of the Mediterranean region, many people following the Mediterranean diet can often go for days at a time without any dairy products. And, while the DASH diet recommends daily lean red mean consumption, the Mediterranean diet mostly excludes red meat and recommends that some form of fish or seafood be eaten on a daily basis (Özkurt, 2015).

Given their many similarities, it’s not surprising several studies have conducted head-to-head comparisons of the DASH diet and Mediterranean diet. Tangney et al. (2014), compared the two diets at how effective they were at slowing down cognitive decline in older adults. 826 older adults with an average age of 81.5 years were recruited for the prospective cohort study.

To help determine diet, participants filled out a self-report 144-item food frequency questionnaire at baseline. They were also a cognitive assessment at baseline and at least two more over the four-year course of the study. Participants were assigned to three groups based on dietary scores monitoring how closely they adhered to either the DASH or Mediterranean diet.

Researchers then compared the DASH and Mediterranean groups relative rates of cognitive decline to a control group that followed a typical carbohydrate-rich diet. The researchers found that both the DASH and Mediterranean dietary patterns resulted in slower rates of cognitive decline that were roughly the same. Additionally, cognitive brain age testing scores for participants who followed the DASH diet the closest were at least 4.4 years younger than the group that followed it the least. The study also found after the four-month intervention that learning and psychomotor function improved significantly for participants following the DASH dietary plan. The researchers noted that findings from similar studies suggest that the cognitive benefits gained from the DASH diet may come quickly.

Researchers say they don’t know the underlying physiological reasons why the DASH and Mediterranean diet helped improved cognitive function, but they theorized that one main factor may be lower inflammation levels. Reduced levels of inflammation have been found among people following both dietary patterns. Inflammation is known to damage brain cells. Also, the antioxidant protections provided by both the DASH diet and Mediterranean diet have been found to help protect against hypertension, obesity, diabetes, and cardiovascular disease. Medical conditions that have all been linked to AD and cognitive decline.

Because the characteristics of both diets are so similar, Tangney et al. (2014), suggest the diets focus on natural, minimally processed foods and a reduced consumption of saturated fats may be more important than the specific diet type. Researchers said the findings point toward the need for more studies focusing on food-based approaches preventative and mitigating effects on cognitive decline. Researchers concluded by saying the stakes for finding out if diet can help prevent AD and vascular dementia have never been higher, considering the rapidly growing population of older adults at risk for the diseases.

Up next, a closer look at a brain-healthy diet that provides a significant cognitive boost even if you don’t follow all that closely.

Sources

Heller, M. (2016, April 4). What is the DASH diet? Retrieved from: http://dashdiet.org/ what_is_the_dash_diet.asp

Özkurt, J. (2015, March 25). Comparing the DASH and the Mediterranean Diets. UNC Rex Connects Health & Wellness Blog. Retrieved from https://www.rexhealthblog.com/dash-vs-mediterranean/

Smith, P., Blumenthal, J., Babyak, M., Craighead, L., Welsh-Bohmer, K., Browndyke, J., . . . & Sherwood, A. (2010). Effects of the Dietary Approaches to Stop Hypertension Diet, Exercise and Caloric Restriction on Neurocognition in Overweight Adults With High Blood Pressure. Hypertension. 55(60). 1331-1358. Retrieved from https:// www.ncbi.nlm.nih.gov/pmc/articles/PMC2974436/

Tangney, C., Hong, L., Wang, Y., Barnes, L., Schneider, J., Bennett, D., & Morris, M. (2014, October 14). Relation of DASH- and Mediterranean-like dietary patterns to cognitive decline in older persons. Neurology. 83(16). 1410-1416. Retrieved from https:// www.ncbi.nlm.nih.gov/pmc/articles/PMC4206157/

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