While there is good evidence to show that a varied and healthy diet helps reduce the risk of a diagnosis, there is little to no research carried out into the effects of a healthy diet on biological markers of the disease.
|A comparison of normal and healthy brains.|
However, very recently, Berti et al investigated just that. They took 54 middle-aged people with a dementia score of zero and cognitive performance was in the normal range for their age and education level. They gained full dietary information and took a number of brain scans for different markers of AD.
First was brain volume, specifically grey matter volume, which is known to decrease in late stages of AD. Then they looked at a molecular marker of AD, amyloid plaques, which tend to accumulate in AD more so than in healthy brains. They also looked at glucose metabolism in the brain, which is a measure of brain activity.
What they found, was that most B vitamins, many minerals, mono and poly-unsaturated fats, vitamin A, C, D, antioxidants and dietary fibre were all associated with lower scores for the AD markers measured. This corresponds to a diet rich in fruit, vegetables, fish and whole grains and low in high-fat dairy, processed meat, fried potatoes, sweets and other sugary food.
Now this is certainly not proof that if you eat a healthy diet you won't get dementia. They only looked at 54 people, who were healthy anyway, but the researchers suggest that dietary interventions may help to prevent, or at least delay dementia. I would like to see what happens when you develop a dietary intervention for those at risk of AD to see whether it really does help. In the mean time, it can't hurt to make sure you eat a little healthier. The benefits of a sustained healthy and varied diet and an active lifestyle are only going to be shown to be greater and greater as we understand more about the effects they have on the body.
Reference: Berti V et al (2015) Nutrient patterns and brain biomarkers of Alzheimer's disease in cognitively normal individuals. J Nutr Health Aging 9(4):413-23. doi: 10.1007/s12603-014-0534-0.