Research: Could Nuts Improve Memory in Alzheimer's?

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Which Nut Is Best for Your Brain? Jon Boyes/Photographer's Choice RF/Getty Images.

Alzheimer's disease, the most common type of dementia, is characterized by progressive memory loss, difficulty reasoning, declines in communication and overall confusion and disorientation. A handful of medications have been approved by the Food and Drug Administration (FDA) to treat the disease, but their effectiveness is very limited.

So, what else can we do? How can we fight Alzheimer's disease?

Along with physical exercise and mental activity, research has increasingly been looking at our diet and asking which foods are correlated with a decreased risk of dementia.

Answer? Nuts, along with several others.

The Research

Recently, researchers conducted a study using mice that had been given a form of Alzheimer's disease. These mice developed memory loss, spatial disorientation, physical motor declines, anxious behaviors and a decreased ability to learn- all symptoms of Alzheimer's disease. The mice with Alzheimer's were divided into three groups; one was fed a typical diet, a second group was given a diet that contained 6% walnuts and a third group was fed a diet with 9% walnuts.

How much is this for humans? According to the authors of the study, this would be equivalent to about 1- 1.5 oz. of walnuts daily for us.

The mice were fed these diets beginning at 4 months and then were tested approximately 9-10 months later.  Tests included measures of motor coordination, learning ability, memory and anxious behavior.

Results

The mice who were fed the diets containing 6% and 9% of walnuts demonstrated significant improvement in all areas tested. There was no difference between the mice who ate the 6 and 9% walnuts. Mice with Alzheimer's disease typically should decline over time in multiple areas, and yet at the end of the study, the mice who were fed the walnut diet performed similarly to the mice who did not have Alzheimer's disease.

 

While the study was conducted using mice and not human subjects, research using mice often helps us understand how the human brain works. Some studies with mice have been replicated in humans and have achieved similar results.

Other Studies on Nuts

Several other studies have been conducted to determine how walnuts affect brain functioning, including the following:

  • Young healthy college students demonstrated improved inferential reasoning (the ability to draw conclusions- or make inferences) after consuming a half of a cup of walnuts for a period of 8 weeks.
  • Walnut extract showed the ability to protect against cell death in the brains of rats.
  • Rats which were fed a diet that included walnuts demonstrated an ability to reduce the buildup of proteins in the brains which can interfere with healthy cognition. The buildup of excess proteins in the brain is one of the hallmarks of Alzheimer's disease.
  • One study evaluated the effect of almond paste on rats' cognitive abilities. Both learning and memory improved for the animals who were fed the almond paste, compared to the mice who were not given it.
  • In a large, six-year study, eating walnuts was associated with improved working memory in older adults.
  • Another research study found that women whose long-term diets contained more nuts performed higher on cognitive tests. The study's authors note that the improvement between those who ate nuts and those who didn't is equivalent to the difference between the functioning of women who are about two years apart. In other words, eating nuts was connected with older women's brains being able to function as if they were two years younger.

The Take-Away?

Several research studies have shown a connection between improved brain health, cognitive functioning and eating nuts. The majority of these studies focused on walnuts, which according to the above study, could have the ability to improve memory and mental ability perhaps even after Alzheimer's disease has developed. This idea is exciting, but it needs to be researched, tested and then replicated in human studies.

Meanwhile, walnuts have also been associated with several other health benefits such as heart health and lower cholesterol levels, so grab a handful, and go nuts!

Sources:

British Journal of Nutrition. Volume 107 / Issue 09 / May 2012, pp 1393-1401. Effects of walnut consumption on cognitive performance in young adults. http://journals.cambridge.org/action/displayAbstract?aid=8549174

Journal of Alzheimer's Disease. 42 (2014) 1397–1405. Dietary Supplementation of Walnuts Improves Memory Deficits and Learning Skills in Transgenic Mouse Model of Alzheimer's Disease. http://iospress.metapress.com/content/n644184610325684/fulltext.pdf

Journal of Alzheimer’s Disease 29 (2012) 773–782. Polyphenol-Rich Foods in the Mediterranean Diet are Associated with Better Cognitive Function in Elderly Subjects at High Cardiovascular Risk. http://iospress.metapress.com/content/w012188621153h61/fulltext.pdf

The Journal of Nutrition. Role of Walnuts in Maintaining Brain Health with Age. 44: 561S–566S, February 5, 2014. http://jn.nutrition.org/content/144/4/561S.full.pdf?ijkey=GSAl.IzWFLPw.&keytype=ref&siteid=nutrition

The Journal of Nutrition. September 2009 vol. 139 no. 9 1813S-1817S. Grape Juice, Berries, and Walnuts Affect Brain Aging and Behavior. http://jn.nutrition.org/content/139/9/1813S.long

Journal of Nutrition, Health & Aging. 2014 May;18(5):496-502. Long-term intake of nuts in relation to cognitive function in older women. http://www.ncbi.nlm.nih.gov/pubmed/24886736

Journal of Nutritional Biochemistry. 2013 May;24(5):912-9. Walnut diet reduces accumulation of polyubiquitinated proteins and inflammation in the brain of aged rats. http://www.ncbi.nlm.nih.gov/pubmed/22917841

Nutricion Hospitalaria. 2012 Nov-Dec;27(6):2109-15. Nootropic and hypophagic effects following long term intake of almonds (Prunus amygdalus) in rats. http://www.ncbi.nlm.nih.gov/pubmed/23588464

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