The role of diet in the regulation of Alzheimer's

Alzheimer's is an incurable, degenerative and fatal disease. In the early stages, the most commonly recognized symptom is memory loss, as well as difficulty recalling recent events. As the disease progresses, symptoms include confusion, irritability, aggression, mood swings, slurred speech, loss of long-term memory, and the sufferer's general social withdrawal as their senses decline.

Alzheimer's disease is on the rise. It has been estimated that 24 million people worldwide suffer from dementia with 4.6 million new cases each year. Alzheimer's is the most common form of dementia with 50-60% of cases. The etiology of the disease remains unclear, but it is very likely to be the result of genetic and environmental factors.

There is evidence that oxidative stress (production and accumulation of amyloid-β-peptides in the brain, responsible for the disease), fats, alcohol and vitamins associated with homocysteine, play a role in the pathogenesis of the disease. There is also a large body of research indicating that cardiovascular risk factors, including hypertension, hypercholesterolemia, smoking, diabetes, obesity, cardiovascular disease, and reduced physical activity, increase the likelihood of Alzheimer's and dementia. It is worth noting that many studies claim that the relationship between diet and Alzheimer's is similar to that of diet and coronary heart disease.

Several in vitro and in vivo animal studies have shown that antioxidant nutrients protect the brain from oxidative stress and other inflammatory damage, but there is little available data from epidemiological studies. Specifically, vitamins C and E have been studied for their relationship with the progression of Alzheimer's disease, but the evidence is conflicting.

Also, recent data show that the B vitamins, such as B6, B12 and folic acid, may play a protective role against Alzheimer's.

Finally, there is substantial epidemiological data from a large number of recent studies demonstrating a protective role of ω-3 fatty acids, such as docosahexaenoic acid in Alzheimer's.

In recent years, research interest in the relationship between nutrition and disease has focused on the study of a comprehensive dietary behavior in relation to the outcome of Alzheimer's, rather than on the analysis of specific nutrients. It is pointed out that the analysis of individual nutrients and foods can miss important interactions between components of a diet, and more importantly because the human diet does not consist of a single nutrient or food.

Thus, research has moved towards examining the relationship between the Mediterranean Diet and the progression of Alzheimer's disease. The first research that showed the possible relationship between the Mediterranean type of diet and the disease was in 2006 by Scarmeas and his associates. The research sample consisted of 2258 people without symptoms of dementia who were closely monitored for 4 years. After 4 years of close medical follow-up, 262 cases of Alzheimer's appeared, and it has been reported that higher adherence to the Mediterranean-type diet was associated with a lower risk of Alzheimer's (40%).

Other research followed which confirmed the results of this first study, however, other groups of people, such as those of different nationalities, need to be further studied. Finally, it is worth noting that Scarmeas and his colleagues in another study carried out in a New York population proved that increased physical activity can reduce the risk of Alzheimer's disease.

In conclusion, the role of nutrition in the regulation of Alzheimer's (AD) needs more scientific study. Nevertheless, we can come to the conclusion that people who follow a Mediterranean diet appear to be less likely to develop this disease.

Phaedra Dagoglou

Dietitian Nutritionist, Msc

In Food Science and Technology/ Food Safety

Sources:

N. Scarmeas, MD, et al, “Mediterranean Diet and Risk for Alzheimer's Disease”, (2006) Ann Neurol, vol. 59, pp. 912-921.

Vassallo, Neville, Scerri. Charles, “Mediterranean Diet and Dementia of the Alzheimer Type”, (2013), Current Aging Science, vol. 6, no 2, pp 150-162

Scarmeas, MD, et al, “Physical Activity, Diet, and Risk of Alzheimer's Disease”, (2009), JAMA, vol. 302, no. 6, pp. 627-637

Lourida, et al, “Mediterranean Diet, Cognitive Function, and Dementia: A Systematic Review”, (2013), vol. 24, no. 4, pp. 479-489

Francesco Sofi et al, “Effectiveness of Mediterranean Diet: Can It Help Delay or Prevent Alzheimer's Disease?”, (2010), Journal of Alzheimer's Disease, vol 20, pp1-7