Food for thought

Abstract

The worldwide number of elderly is rising, and simultaneously the number of people with dementia is also increasing (Blennow, et al., 2006; Jicha and Carr, 2010). In the past 20 years the care of dementia patients has remarkably improved (Winblad, et al., 2016). Many detrimental and protective factors that affect the risk of dementia have been identified through research (Alzheimer's Association, 2016). Currently, no effective treatment of dementia exists (Winblad, et al., 2016). Thus, dementia is a challenging ongoing global public health burden on society, which needs targeted research strategies to identify treatments to delay the onset of the disease, to slow disease progression or to cure dementia (Winblad, et al., 2016). One research strategy is to investigate modifiable risk factors in relation to dementia such as nutrition, which is an important modifiable lifestyle factor. Nutrition has an impact on a wide range of diseases including cardiovascular diseases and Diabetes Mellitus (Archundia Herrera, et al., 2017), which in turn are risk factors for dementia (Alzheimer's Association, 2016). A growing body of evidence points to an important role of nutrition in the development and clinical progression of dementia (Gustafson, et al., 2015), however, many gaps still exist. Therefore, we aimed to examine the role of nutrition in relation to all-cause dementia, Alzheimer's dementia (AD) and memory decline in elderly and oldest old from the German Study on Ageing, Cognition and Dementia in Primary Care Patients (AgeCoDe). In study 1 we investigated the effects of plasma concentrations vitamin A, beta-carotene, vitamin D, vitamin E and oxidized-low density lipoprotein (ox-LDL) on clinically diagnosed AD in the oldest old over a follow-up time of seven years. We demonstrated that higher concentrations of vitamin D were associated with lower incident AD and in particular subjects with vitamin D deficiency (<20 ng/mL) were at increased risk for AD. The other vitamins and ox-LDL were unrelated to AD or all-cause dementia. Thus, our results supported the advice for monitoring vitamin D status, and to provide more sun exposure and vitamin D supplementation to subjects with vitamin D deficiency. Our null results between the other vitamins or ox-LDL with AD or all-cause dementia were in line with previous observational studies. In study 2 we aimed to assess whether the polyunsaturated fatty acids (PUFA) composition of serum phospholipids (i.e. absolute concentrations and percentage distributions), especially eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), linoleic acid (LA), dihomo-γ-linolenic acid (DGLA) or arachidonic acid (AA) were associated with increased risk of incident clinically diagnosed all-cause dementia or AD in the oldest old over a follow-up time of seven years. Our results showed that higher concentrations of EPA were associated with a lower risk of incident AD. In addition, from the literature there is a hypothesis of the influence of apolipoprotein E ε4 (APOE ε4) on fatty acids (Barberger-Gateau, et al., 2011; Grimm, et al., 2017.) We observed that higher concentrations of EPA were associated with a decreased risk of all-cause dementia and AD in APOE ε4 non-carriers, but not in APOE ε4 carriers. The other PUFAs were unrelated to the disease. Strikingly, aforementioned effects were only found for higher concentrations of EPA, but not for percentage distribution of concentrations of EPA and the other PUFAs, including DHA. This discrepancy might be explained by the dependency on the proportions of other fatty acids included in the fatty acid assessment or due to a lack of power for DHA. Our study supports the advice to eat fatty fish regularly. In study 3 we examined whether dietary intake of red and white wine, coffee, green tea, olive oil, fresh fish, fruits and vegetables, red meat and sausages, assessed by an 8-item questionnaire, would be associated with increased risk for incident AD or memory decline over a follow-up time of 10 years. We observed that only higher red wine intake was associated with a lower risk of incident AD. Interestingly, this was true only for men, while in women higher red wine intake was associated with a higher risk of incident AD, and higher white wine intake with a more pronounced memory decline. According to our findings, women could be more susceptible to detrimental effects of alcohol. However, we also concluded that the use of a brief questionnaire is a challenge as we were only able to report an effect of red wine intake for AD, and only in men, which contradicts previous study results.