(CNN) Meals from the sunny Mediterranean have been linked to stronger bones, a healthier heart and longer life, along with a reduced risk for diabetes and high blood pressure.

Now you can add lowering your risk for dementia to the ever growing list of reasons to follow the Mediterranean diet or one of its dietary cousins.

New research being presented at the Alzheimer's Association International conference in London this week found healthy older adults who followed the Mediterranean or the similar MIND diet lowered their risk of dementia by a third. "Eating a healthy plant-based diet is associated with better cognitive function and around 30% to 35% lower risk of cognitive impairment during aging," said lead author Claire McEvoy, of the University of California, San Francisco's School of Medicine.

McEvoy stressed that because the study was conducted in a nationally representative older population "the findings are relevant to the general public." "While 35% is a greater than expected decrease for a lifestyle choice, I am not surprised," said Rudolph Tanzi, who directs the Genetics and Aging Research Unit at Massachusetts General Hospital and recently co-authored a book with Deepak Chopra on genes and aging called "Super Genes."

"The activity of our genes is highly dependent on four main factors: diet, exercise, sleep and stress management," said Tanzi, who was not involved in the study. "Of these, perhaps diet is most important."

McEvoy's study investigated at the eating habits of nearly 6,000 older Americans with an average age of 68. After adjusting for age, gender, race, low educational attainment and lifestyle and health issues -- such as obesity, hypertension, diabetes, depression, smoking and physical inactivity -- researchers found that those who followed the MIND or Mediterranean diet had a 30% to 35% lower risk of cognitive impairment.

The more people stayed on those diets, said McEvoy, the better they functioned cognitively.

Those who marginally followed the diet also benefited, but by a much smaller margin. They were 18% less likely to exhibit signs of cognitive impairment.

What are the Mediterranean and MIND diets?

Forget lasagne, pizza, spanakopita and lamb souvlaki -- they are not on the daily menu of those who live by the sunny Mediterranean seaside.

The true diet is simple, plant-based cooking, with the majority of each meal focused on fruits and vegetables, whole grains, beans and seeds, with a few nuts and a heavy emphasis on extra virgin olive oil. Say goodbye to refined sugar or flour and fats other than olive oil, such as butter, are consumed rarely, if at all.

Meat can make a rare appearance, but usually only to flavor a dish. Instead, meals may include eggs, dairy and poultry, but in much smaller portions than in the traditional Western diet. Fish, however, are a staple.

The MIND diet takes the best brain foods of the Mediterranean diet and the famous salt-reducing DASH diet, and puts them together. MIND encourages a focus on eating from 10 healthy food groups while rejecting foods from five unhealthy groups.

MIND stands for Mediterranean-DASH Intervention for Neurodegenerative Delay, with DASH standing for Dietary Approaches to Stop Hypertension.

MIND was developed by Martha Clare Morris, a nutritional epidemiologist at Chicago's Rush University Medical Center in the US.

Those who follow MIND reject butter and stick margarine, red meats, cheeses, fried or fast food and sweets. Instead, they eat at least six servings a week of green leafy vegetables such as spinach or kale, and at least one serving a day of another vegetable. Three servings a day of whole grains are a must.

They also add in at least three servings of beans, two or more servings of berries, two servings of chicken or turkey, and once serving of fish each week. Olive oil is their main cooking ingredient, and they drink a glass of wine a day.

Morris has some powerful stats behind her diet.

In 2015, she studied 923 Chicago-area seniors and found those who say they followed the diet religiously had a 53% lower chance of getting Alzheimer's, while those who followed it moderately lowered their risk by about 35%. Follow-up observational studies showed similar benefits.

Morris and her colleagues are currently recruiting volunteers for a three-year clinical study to try to prove the link.

Additional evidence

A second study presented at the conference also examined the impact of the MIND diet. Researchers from Wake Forest School of Medicine followed 7,057 women, average age 71, over almost 10 years and found those who most closely followed the MIND diet had a 34% reduction in the risk of developing Alzheimer's.

A third study at the conference looked at the dietary habits of 2,223 dementia-free Swedish adults over six years who followed the Nordic Prudent Dietary Pattern (NPDP) diet, which avoids sweets and fatty and processed foods. Instead, the diet emphasizes eating non-root vegetables, apple/pears/peaches, pasta/rice, poultry, fish, vegetable oils, tea and water, and light to moderate wine intake.

Swedes who stuck to the diet at a moderate or higher level preserved their cognitive function better than those who ate more processed and fatty foods.

That comes as no surprise to neurologist Rudy Tanzi.

Despite the similarities of the results, experts point out that all of this research is observational, meaning that it is based on reports by individuals as to what they eat. To prove the connection between diet and dementia risk, said McEvoy, researchers will need to move to scientifically controlled experiments.

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