Background: The associations between 1-carbon metabolism (OCM) nutrients (methionine, folate, vitamin B-6, and vitamin B-12) and Alzheimer disease (AD) remains inconclusive. Objectives: This study aimed to investigate the association of dietary OCM nutrients with subsequent risk of AD and further assess whether participants with high genetic risk for AD might benefit from dietary OCM nutrients. Methods: We analyzed data from 192,214 participants who completed at least one 24-h dietary questionnaire and had no previous history of AD based on the UK Biobank. Nutrients intake was calculated using McCance and Widdowson's The Composition of Food and USDA's Food and Nutrient Database for Dietary Studies. Cox proportional models with restricted cubic splines were applied to explore the associations. Results: Over a median follow-up of 13.35 y, 959 cases of AD (41 early-onset cases and 918 late-onset cases) were identified. Compared with those in the low-intake OCM group (quartile 1), participants in the high-intake OCM group (quartile 4) had reduced risk of developing AD. The corresponding hazard ratios (HRs) and 95% confidence intervals (CIs) for methionine, folate, vitamin B-6, and vitamin B-12 intake were 0.66 (0.54, 0.80), 0.71 (0.58, 0.87), 0.71 (0.59, 0.87), and 0.77 (0.64, 0.93), respectively. Similar associations were observed in late-onset AD. In early-onset AD, high methionine and vitamin B-12 intake were associated with 70% (HR: 0.30; 95% CI: 0.10, 0.86) and 71% (HR: 0.29; 95% CI: 0.09, 0.96) reduction in risk, respectively. Participants with low genetic risk and high OCM nutrients intake had >75% reduced AD risk compared with high-risk, low-intake participants. Conclusions: In this prospective cohort study, we found that higher intake of OCM nutrients is associated with reduced risk of AD. Participants with high genetic risk of AD are more likely to benefit from dietary OCM nutrients intake.

While the oral health of persons with dementia has been shown to be poor, no systematic reviews have been published that examined the topic in depth, including participants with dementia representing the full spectrum of disease severity, and evaluating a broad scope of oral health assessments. The aim of this study was to conduct a current literature review to fill this gap in knowledge. A systematic search of 5 databases (CINAHL, PubMed, EMBASE, Scopus, and ISI Web of Science) was conducted to identify all relevant studies published up to May 2016. There were no exclusions related to study type, severity of dementia, dentate status, or living arrangements. Results were reported descriptively and summarized. Meta-analyses were performed where possible and reported as mean difference (MD) or standardized mean difference (SMD), with a 95% confidence interval (CI). Twenty-eight studies were identified. Assessments were conducted of tooth status, active dental caries, hygiene (plaque/calculus) of natural and artificial teeth, periodontal diseases, denture status (retention, stability, denture-related mucosal lesions), and oral health-related quality of life. Across all evaluations, persons with dementia generally had scores/results suggestive of poor oral health. In meta-analyses, compared with persons without dementia, those with dementia had a significantly fewer number of teeth (MD, -1.52; 95% CI, -0.2.52 to -0.52; P = 0.003; n = 13 studies), more carious teeth (SMD, 0.29; 95% CI, 0.03 to 0.48; P = 0.028; n = 9), significantly worse oral hygiene evaluated using a broad range of assessment tools (SMD, 0.88; 95% CI, 0.57 to 1.19, P < 0.0001; n = 7), and significantly poorer periodontal health (SMD, 0.38; 95% CI, 0.06 to 0.70; P = 0.02; n = 6 studies). The oral health status of persons with mild to severe forms of dementia, who were living in both the community and residential care facilities, was found to be poor across a broad range of dental assessments. Knowledge Transfer Statement: The results of this study define the scope of oral issues and quantify the degree of impairment in individuals with dementia, evaluated using a variety of oral health measures. The results revealed that poor oral health is associated with dementia.