Can a diet prevent dementia?
Scientists at Rush University in the US have developed the ‘MIND’ diet, aimed at slowing down the impact of ageing on the brain. But can a diet really lower your chances of getting Alzheimer’s disease or any other type of dementia?
We looked at the evidence and talked to an expert on Alzheimer’s disease research to find out.
What is the MIND diet?
The 'Mediterranean-DASH Intervention for Neurodegenerative Delay' diet, to give its full name, is an attempt to pull together the results of previous research into diet and the brain, and highlight the foods that may help protect against dementia. In particular, it uses elements from the Mediterranean diet, which is based on the traditional diets eaten by people in southern Italy and Greece, and the DASH diet for lowering blood pressure.
Dr Clare Walton, research communications manager at the Alzheimer's Society, says there is "moderately strong" evidence that the Mediterranean diet can reduce the chances of getting dementia. A summary of all the published studies around the Mediterranean diet showed that 9 out of 12 good-quality studies found a lower chance of dementia, and better thinking skills, among older people who ate a Mediterranean-type diet.
Opinions vary about what exactly makes up a Mediterranean diet, but olive oil, wholegrains, plenty of vegetables and fruit, some fish, and moderate quantities of red wine are usually included. However, the definition is quite loose.
The DASH (Dietary Advice to Stop Hypertension) diet was developed specifically to target blood pressure. It includes low fat dairy products, as well as wholegrains and fruit and vegetables, and limits salt, sugar, and fat. There's good scientific evidence that it reduces blood pressure, and high blood pressure is known to increase the chances of dementia. However, DASH has not been tested for its effect on dementia.
To create the MIND diet, researchers picked 10 food groups perceived to be 'brain healthy' and common in the Mediterranean and DASH diets, including olive oil, wholegrains, vegetables, nuts, berries, beans, fish and poultry, and red wine. As well as the 10 foods to include, researchers drew up a list of 5 foods to avoid where possible. Red meat, fast or fried food, cheese, butter, pastries and sweets are all restricted. The diet sets out how much of each food type people should eat.
"There's lots of benefits to the way it's been developed," says Dr Walton. "It is well defined - everything is quantified. It was a bit of a best guess, but it's a good place to start to talk about what seems to work."
Does it work?
There is some evidence that people who eat a diet similar to the Mediterranean and DASH diets, and the combined approach 'MIND' diet, have a lower risk of getting dementia than people with a less healthy diet. In one study looking at the diets of 923 older people in the US, those whose diet was judged to be close to the MIND diet were less likely to be diagnosed with Alzheimer's disease.