Correspondence to: William B. Grant, PhD, Sunlight, Nutrition and Health Research Center (SUNARC), 2107 Van Ness Ave., Ste. 403B, San Francisco, CA 94109 (e-mail: wgrant{at}sunarc.org).
The recent report linking cancer as a risk factor for cognitive dysfunction at a statistically significant level and dementia at a nonstatistically significant level (1) is interesting and highlights the possible risk of unwanted side effects from cancer treatment. However, the link between cancer and cognitive dysfunction is likely due to shared risk factors as well. The study overlooked the role of dietary and lifestyle factors (e.g., exercise, smoking) in modifying the risks of both cancer and dementia among the elderly.
Although genetics plays an important role in the etiology of cognitive dysfunction and dementia (1), so do diet and lifestyle (25). Furthermore, Japanese Americans and African Americans living in the United States have a two and four times greater risk, respectively, of Alzheimer disease than when living in their ancestral homelands, which is statistically correlated with national consumer dietary supply factors in linear regression analyses with r2 values ranging from 0.69 to 0.93 (2). Total energy and fat intake are directly associated with risk of Alzheimer disease, whereas fish and cereals/grains intake are inversely associated (2).
Cancer risk is also strongly linked to dietary and lifestyle factors [including smoking (6,7)]. Intake of animal products that are high in both fat and protein is associated with risk for many common cancers, such as breast and colon cancer (6). The mechanisms may include production of insulin-like growth factor I (IGF-I) (6) and endogenous sex hormones. A recent review highlighted the Western high-fat and refined-sugar diet and physical inactivity as important risk factors for cancer (7). Thus, cancer and dementia share several dietary and lifestyle risk factors.
In conclusion, recent findings indicate that contributions to cognitive dysfunction and dementia from both diet and lifestyle may occur prior to the development of cancer and its treatment. Further studies are required to determine the relative contributions from each.
REFERENCES
(1) Heflin LH, Meyerowitz BE, Hall P, Lichtenstein P, Johansson B, Pedersen NL, et al. Cancer as a risk factor for long-term cognitive deficits and dementia. J Natl Cancer Inst 2005;97:8546.
(2) Grant WB. Dietary links to Alzheimer's disease. Alz Dis Rev 1997;2:4255 (Available at http://www.sunarc.org/JAD97.pdf).
(3) Mattson MP. Existing data suggest that Alzheimer's disease is preventable. Ann N Y Acad Sci 2000;924:1539.
(4) Grant WB, Campbell A, Itzhaki RF, Savory J. The significance of environmental factors in the etiology of Alzheimer's disease, J Alz Dis 2002;4:17989.
(5) Solfrizzi V, D'Introno A, Colacicco AM, Capurso C, Del Parigi A, Capurso S, et al. Dietary fatty acids intake: possible role in cognitive decline and dementia. Exp Gerontol 2005;40:25770.[CrossRef][ISI][Medline]
(6) Grant WB. An ecologic study of dietary and solar UV-B links to breast carcinoma mortality rates. Cancer 2002;94:27281.[CrossRef][ISI][Medline]
(7) Barnard RJ. Prevention of Cancer Through Lifestyle Changes. Evid Based Complement Alternat Med 2004;1:2339.
Response to this Correspondence
![]() |
||||
|
Oxford University Press Privacy Policy and Legal Statement |