Diet is key to reducing Alzheimer's risk

Alzheimer's is not an inevitable part of ageing and the risk of developing it could be significantly lowered through changes to diet and lifestyle, according to experts in the relationship between diet and cognitive function.Speaking at the Food for the Brain conference in London last month, professor David Smith, who founded an internationally renowned centre for studying dementia in Oxford, said: "Alzheimer's disease is a complex, multi-factoral disease that often starts more than 25 years before it is expressed or diagnosed as dementia." While people with a certain polymorphism (apoE4) of a gene (apoE) connected to fat metabolism were more likely to develop the disease, it was "rarely purely genetic", he said.

As for the relationship between nutrition and cognitive decline, many scientists were now convinced that elevated levels of homocysteine and correspondingly low consumption of vitamin B12 and folic acid were associated with increased risk of dementia, he said. While it was impossible to reverse cognitive impairment in subjects that already had moderate or severe symptoms, supplementation with folic acid and vitamin B12 could potentially reduce the risk of developing dementia and even arrest the rate of decline in those who had already developed mild forms of Alzheimer's disease.

The fact that the recent VITAL (Vitamins to Slow Alzheimer's Disease) study did not show any positive benefits from supplementation of these nutrients did not prove that they did not work, he claimed. "The study was badly designed; many of the volunteers already had moderate or severe Alzheimer's."

As to whether the omega-3 fatty acids EPA and DHA could reduce the risk of Alzheimer's, the jury was still out, he said: "There are conflicting reports."

However, a recent study had suggested that high ratios of omega-6 to omega-3 fatty acids could increase risk.

Another substance worth exploring was curcumin, the active component in turmeric, said Jeya Henry, professor of human nutrition at Oxford Brookes University. "Curcumin may reverse the build up of neural plaque implicated in Alzheimer's. Rat studies have shown it suppresses amyloid accumulation in the brain. The epidemiology shows that people who consume lots of turmeric also have a lower prevalence of dementia. But we need human clinical studies to take the research on to the next stage."