Dietary Factors May Influence Dementia Risk

BORDEAUX, France, Nov. 13 -- A diet rich in fruits, vegetables, fish, and omega-3 fish oil may afford protection against dementia, investigators here concluded.
Action Points
Explain to interested patients that regular consumption of fruits, vegetables, and fish may reduce the risk of Alzheimer's disease and dementia.
Note that some of the benefit appears to be limited to people who have a particular lipid-related genotype.
Older individuals who reported daily consumption of fruits and vegetables had almost a 30% lower risk of dementia compared with people who reported less frequent consumption, Pascale Barberger-Gateau, Ph.D., of University Victor Segalen, and colleagues, reported in the November issue of Neurology.
Weekly fish consumption reduced the risk of Alzheimer's disease and all-cause dementia, but only in ApoE ε4 noncarriers, the researchers found. Regular intake of omega-3 fish oils also reduced the risk of dementia, whereas omega-6 consumption that was not balanced by omega-3 or fish increased the risk of dementia in ApoE ε4 noncarriers.
The results add to previous evidence of dietary associations with dementia risk, but the authors emphasized that the evidence falls short of definitive proof.
"More research is needed to identify the optimal quantity and combination of nutrients that could be protective before implementing nutritional recommendations," they concluded.
Interest in modifiable risk factors for Alzheimer's disease and other forms of dementia has led to several examinations of dietary factors, in particular fat and antioxidants. In the PAQUID French cohort study of older adults, regular fish consumption was associated with a significantly decreased risk of dementia during seven years of follow-up (BMJ 2002; 325: 932-933). Several other studies have demonstrated similar associations, the authors noted.
The protective effect of fish consumption has been attributed to high concentrations of omega-3 fatty acids, which are major components of neuron membranes and have vascular and anti-inflammatory effects, they continued. However, epidemiologic studies have yielded inconsistent results on the association of fish and omega-3 fatty acid consumption with dementia. Moreover, demographic, socioeconomic, and other dietary factors could confound the association.
So Dr. Barberger-Gateau and colleagues examined various components of a diet rich in fat or antioxidants and associations with dementia, adjusting for individual characteristics and potential interactions between foods and ApoE genotype.
The study population comprised 8,085 adults without dementia ages 65 and older in the Three City cohort study, an ongoing evaluation of vascular risk factors and dementia.
The participants were enrolled during 1999 and 2000, and each had at least one clinic visit during four years of follow-up. An independent committee of neurologists confirmed 281 cases of dementia during the follow-up period.
The analysis showed that daily consumption of fruits and vegetables significantly decreased the risk of all-cause dementia, as reflected by an adjusted hazard ratio of 0.72.
Weekly fish consumption reduced the risk of Alzheimer's disease by 35% (HR: 0.65, 95% CI: 0.43 to 0.994).
Regular fish consumption also reduced the risk of all-cause dementia by 40% (HR: 0.60, 95% CI: 0.40 to 0.90), but only in study participants who were ApoE ε4 noncarriers.
Regular consumption of omega-3 fatty acids was associated with a nonsignificant 54% reduction in the hazard ratio for all-cause dementia.
A diet rich in omega-6 oils doubled the risk of dementia in ApoE ε4 noncarriers in the absence of compensatory consumption of omega-3 oils or fish (HR: 2.12, 95% CI: 1.30 to 3.46).
"Given that most individuals are ApoE ε4 noncarriers, these findings could have considerable implications in terms of public health," the authors concluded.
The authors reported no conflicts of interest.Primary source: NeurologySource reference: Barberger-Gateau P, et al "Dietary patterns and risk of dementia. The Three-City Cohort Study"Neurology 2007; 69: 1921-1930.