Researchers recently studied the effect of diet on the cognitive ability of older adults.
Alzheimer’s disease affects almost 50 million people worldwide. By the year 2050, that number is expected to rise to 115 million. It is the most common cause of dementia, and it begins with mild memory loss. In its late stages, Alzheimer’s disease leads to an individual completely losing the ability to respond to their environment.
The causes of Alzheimer’s disease are not understood. Much research has been conducted, and very little is known about how to treat or prevent Alzheimer’s. Researchers know that Alzheimer’s patients lose the connections, known as synapses, between their neurons as they lose their ability to remember.
It is also thought that chronic inflammation of the nervous system may play a part in Alzheimer’s disease development, and it may be caused by the body’s reaction to gut microbes. Researchers have found that Alzheimer’s disease patients have higher levels of gut bacteria that cause inflammation.
Researchers from Wake Forest School of Medicine in Wake Forest, NC have recently published a study in eBioMedicine studying the effects of the modified Mediterranean-ketogenic diet (MMKD) on the gut bacteria of Alzheimer’s disease patients compared to the American Heart Association Diet.
The modified Mediterranean-ketogenic diet is a keto-type diet that allows higher carbohydrate consumption than the traditional keto diet. This permits more vegetables, fruits, healthy fats, and proteins from sources like olive oil and fish.
The American Heart Association Diet is a low-fat diet that consists of a large amount of fruits and vegetables, whole grains, low-fat dairy products, and high fiber foods. Participants eat protein from sources such as lean meat and nuts.
The study followed 17 subjects who were at risk for Alzheimer’s disease. Eleven of the subjects were diagnosed with mild cognitive impairment (MCI). The subjects were randomly assigned to a modified Mediterranean-ketogenic diet or an American Heart Association diet for six weeks. During the next six weeks, participants ate their normal diet. For the final six weeks, the participants were assigned to the second diet.
At the beginning of the study, at the end of the first six weeks, and at the end of the final six weeks, participants were given a spinal tap. Stool and blood samples were also taken at the beginning and end of each diet. During the study, participants kept a food diary and their blood sugar was monitored weekly to ensure they were sticking to their diet plans.
At the end of the study, data from the participants’ spinal tap, stool samples, and blood sugar was analyzed. Researchers found that there were specific bacterial families that were found in the gut bacteria of the MCI participants. Some of these bacteria are associated with inflammation. The results also suggested that the MMKD has benefits for participants with MCI, and decreased the levels of compounds associated with poor short-term memory.
Further research for a longer period of time and with a larger study group would validate the study findings. Researchers are hopeful that this study identified markers that indicate MCI leading to Alzheimer’s disease, and a solid link between diet and mental cognition.
Written by Rebecca K. Blankenship, B.Sc.
Reference: Nagpal R, Neth B, Wang S, Craft S, Yadav H. Modified Mediterranean-ketogenic diet modulates gut microbiome and short-chain fatty acids in association with Alzheimer’s disease markers in subjects with mild cognitive impairment. EBioMedicine. 2019;47:529-542. doi:10.1016/j.ebiom.2019.08.032
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