Dietary patterns and risk of dementia: The Three-City cohort study
Barberger-Gateau P, Raffaitin C, Letenneur L, Berr C, Tzourio C, Dartigues JF, et al.;
Commented by , 31 Jan 2008
Aim of the study
To analyze the relationship between dietary patterns and risk of dementia or Alzheimer's disease (AD), adjusting for sociodemographic and vascular risk factors, and taking into account the ApoE genotype.
Method
Cohort of 8,085 non demented participants aged 65 and over from the three French cities of Bordeaux, Dijon, Montpellier, examined in 1999-2000 then at least once over 4 years, looking for incident cases of dementia and AD.
Results
281 incident cases of dementia were found, including 183 with AD. Daily consumption of fruits and vegetables was associated with a decreased risk of all causes of dementia (hazard ratio [HR] 0.72, 95% CI 0.53 to 0.97) in the fully adjusted models.
Weekly consumption of fish was associated with a reduced risk of AD (HR 0.65, 95% CI 0.43 to 0.994) and all causes of dementia but only among ApoE ε4 noncarriers (HR 0.60, 95% CI 0.40 to 0.90).
Regular use of omega-3 rich oil was associated with a decreased risk of borderline significance for all causes of dementia (HR 0.46, 95% CI 0.19 to 1.11). Regular consumption of omega-6 rich oils not compensated by consumption of omega-3 rich oils or fish was associated with an increased risk of dementia (HR 2.12, 95% CI 1.30 to 3.46) among ApoE ε4 noncarriers.
Professor Gauthier's comments
The authors conclude that frequent consumption of fruits and vegetables, fish and omega-3 rich oils may decrease the risk of dementia and AD, especially among ApoE ε4 noncarriers.
These results are consistent with prior findings that fish consumption may be protective against dementia, possibly because of the high content in long-chain omega-3 polyunsaturated fatty acids (PUFA), in particular docosahexaenoic acid (DHA), that are major components of neuron membranes and have vascular and anti-inflammatory properties.
This research can also be broadened to the Mediterranean diet at large which has been extensively studied and reported since 2006 to be protective against AD (ref. 1, ref. 2, ref. 3). A systematic literature review on the effects of omega-3 fatty acids on measures of cognitive function in normal aging and dementia was published by Issa et al. (ref. 4), suggesting indeed a possible association between omega-3 fatty acids and a reduced risk of dementia. Panza et al. have suggested that intervention trials with omega-3 PUFA from olive oil or fish be conducted (ref. 5). The results of the Three-City study do certainly support the need for such prospective randomized studies, with the possibility that such dietary supplementation may only be effective in ApoE ε4 noncarriers. Pharmacogenomics, so far dedicated to the study of drugs interacting with genes (ref. 6), may thus be also relevant to dietary supplements. ApoE status of participants must thus be part of the plan of analysis of intervention studies with drugs and with dietary supplements.
References
1. Scarmeas N, Stern Y, Tang MX, Mayeux R, Luchsinger JA. Mediterranean diet and risk for Alzheimer's disease. Annals of Neurology 2006; 59 (6); 912-921
2. Scarmeas N, Stern Y, Mayeux R, Luchsinger JA. Mediterranean diet, Alzheimer disease, and vascular mediation. Archives of Neurology 2006; 63 (12); 1709-1717. [Epub 2006 Oct 9]
3. Kawas C. Diet and the Risk of Alzheimer's Disease. Annals of Neurology 2006, 59 (6); 877-879
4. Issaa AM, Mojicaa WA, Mortona SC, Trainaa S, Newberrya SJ, Hiltona LG et al. The Efficacy of Omega-3 Fatty Acids on Cognitive Function in Aging and Dementia: A Systematic Review. Dementia and Geriatric Cognitive Disorders 2006; 21 (2); 88-96
5. Panza F, Capurso C, D'Introno A, Colacicco AM, Chirico M, Capurso A, et al. Dietary polyunsaturated fatty acid supplementation, pre-dementia syndromes, and Alzheimer's disease. Journal of the American Geriatrics Society 2007; 55 (3); 469–470
6. Poirier J, Gauthier S. Pharmacogenomics and the treatment of sporadic Alzheimer’s disease: a decade of progress. Current Pharmacogenomics 2008; 6; in press