By Margarita Nahapetyan
People who eat Mediterranean-style diet, which is rich in fish, olive oil, vegetables, legumes, fruits, cereals, and unsaturated fatty acids, have much less chance to develop mild cognitive impairment, sometimes called as borderline dementia, according to a new study. The study also suggests that Mediterranean food eaters with mild cognitive impairment are less likely to transition into Alzheimer's disease.
Mild cognitive impairment (MCI) is a condition in which a person has problems with memory, language, or another mental function that is greater than would be expected for one's age. Mild cognitive impairment can be an early warning sign that a person is more likely to develop Alzheimer's disease. Unfortunately, at this point, experts cannot say yet in which cases the condition of mild cognitive impairment will be transitioned into Alzheimer's disease.
"We know from previous research that a healthy diet like this is protective for cardiovascular risk factors like cholesterol, hypertension and diabetes. Now this current study shows it may help brain function too," said Nikolaos Scarmeas, assistant professor of clinical neurology at the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center.
Scarmeas and his team at Columbia University examined and screened 1,393 individuals with no cognitive impairments between 1992 and 1999. They also analyzed 482 patients with mild cognitive impairment. In addition, all study participants were interviewed and asked questions about their eating and drinking habits.
The results showed that of the 1,393 participants with normal brain function, 275 developed cognitive impairment during an average 4.5 year follow-up period, and those who ate a strict Mediterranean diet lowered the risk of developing mild cognitive impairment by 28 per cent. Individuals who followed a Mediterranean diet in the middle group had a 17 per cent lower risk.
Among the group of 482 study participants who had mild cognitive impairment at the beginning of the study, 106 developed Alzheimer's disease during an average follow-up period of 4.3 years. The one-third of participants with the highest consumption of Mediterranean food had a 48 per cent less chance of developing Alzheimer's disease than those who scored in the bottom third. And the middle group had a 45 per cent reduced risk of the disease.
This risk might be reduced because the Mediterranean diet, the researchers explain, has been linked to improvements of cholesterol levels, blood sugar levels and blood vessel health, insulin resistance, lower markers of inflammation, which in their turn reduce the risk of developing a brain dysfunction.
The researchers believe that individual components of the diet could be responsible for what keeps our brains healthy. "For example, potentially beneficial effects for mild cognitive impairment or mild cognitive impairment conversion to Alzheimer's disease have been reported for alcohol, fish, polyunsaturated fatty acids and lower levels of saturated fatty acids," they said.
However, nobody knows yet whether it is some single food, or some mysterious combination of nutrients or other aspects of the diet that bring all these unbelievable effects. Nobody knows exactly which component of the Mediterranean diet makes it such a healthful way of eating.
The scientists emphasized that additional studies are needed to confirm the role of this or other dietary factors in the development of cognitive impairment and Alzheimer's disease. "This is not a clinical trial, it is only an observational study," Scarmeas noted. "We cannot, therefore, say that the Mediterranean diet is definitely useful for neurological conditions such as mild cognitive impairment. Having said that, since we already know that Mediterranean diet is helpful for other conditions (coronary heart disease, diabetes, hypertension, etc.), it makes sense."
Exploration of possible biological mechanisms that link the Mediterranean food and dementia are yet to be investigated and future studies are believed to provide a more complete and convincing picture.
Rebecca Wood, chief executive of the Alzheimer's Research Trust, gave her advice: "Diet almost certainly plays a part in every person's Alzheimer's risk - and diet remains a magnet for research because it could offer a relatively inexpensive way to fight a disease that ruins countless lives. By reducing salt and saturated fat intake and adding oily fish and lots of fruit and vegetables to our shopping baskets, we can help reduce the risk of developing dementia as well as reaping the countless other benefits of living a healthy lifestyle."