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Background & Aims: Undernutrition may negatively impact cognitive function, but evidence of this relationship is not yet consolidated. Under the "PROtein enriched MEDiterranean diet to combat undernutrition and promote healthy neuroCOGnitive ageing" (PROMED-COG) project, we evaluated the association between undernutrition, and cognitive decline and incident dementia in older adults., Methods: Retrospective data harmonization was performed on three Italian population-based studies: the Italian Longitudinal Study of Ageing (ILSA), the Progetto Veneto Anziani (Pro.V.A.), and the Bollate Eye Study-Follow-Up (BEST-FU). The associations between undernutrition, operationalized using the Global Leadership Initiative on Malnutrition (GLIM) criteria, and decline on the Mini-Mental State Examination (MMSE) or dementia incidence follow-up were evaluated with Cox proportional hazard regression models., Results: The pooled cohort comprised 9071 individuals (52% females) aged between 42 and 101 years. The prevalence of undernutrition at the baseline was 14.3%, significantly higher among females (15.4% vs 13%) and in older age, ranging from 3.5% in those aged <60 years to 28.8% in those 85+ years. Undernutrition was associated with both cognitive decline over a median 8.3-year follow-up (Hazard Ratio (HR) 1.20, 95% Confidence Interval (CI) 1.02-1.41, p = 0.028) and incidence of dementia over a median 8.6-year follow-up (HR = 1.57, 95%CI 1.01-2.43, p = 0.046). For cognitive decline, the association with undernutrition was more marked in males than females (HR = 1.36, 95%CI 1.05-1.77, p = 0.019 vs HR = 1.10, 95% CI 0.89-1.36, p = 0.375)., Conclusion: Undernutrition is prevalent among older people and is associated with an increased risk of experiencing cognitive decline and dementia. The prevention and early identification of undernutrition could be an important nonpharmacologic strategy to counteract neurodegeneration., Competing Interests: Conflict of interest None., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Plant-based diets may provide protection against cognitive decline and Alzheimer's disease, but observational data have not been consistent. Previous studies include early life confounding from socioeconomic conditions and genetics that are known to influence both cognitive performance and diet behaviour. This study investigated associations between Mediterranean (MED) diet and MIND diets and cognitive performance accounting for shared genotype and early-life environmental exposures in female twins., Methods: Diet scores were examined in 509 female twins enrolled in TwinsUK study. The Cambridge Neuropsychological Test Automated Battery was used to assess cognition at baseline and 10 years later (in n = 275). A co-twin case-control study for discordant monozygotic (MZ) twins examined effects of diet on cognitive performance independent of genetic factors. Differences in relative abundance of taxa at 10-year follow-up were explored in subsamples., Results: Each 1-point increase in MIND or MED diet score was associated with 1.75 (95% CI: - 2.96, - 0.54, p = 0.005 and q = 0.11) and 1.67 (95% CI: - 2.71, - 0.65, p = 0.002 and q = 0.02) fewer respective errors in paired-associates learning. Within each MZ pair, the twin with the high diet score had better preservation in spatial span especially for MED diet (p = 0.02). There were no differences between diet scores and 10-year change in the other cognitive tests. MIND diet adherence was associated with higher relative abundance of Ruminococcaceae UCG-010 (0.30% (95% CI 0.17, 0.62), q = 0.05) which was also associated with less decline in global cognition over 10 years (0.22 (95% CI 0.06, 0.39), p = 0.01)., Conclusions: MIND or MED diets could help to preserve some cognitive abilities in midlife, particularly episodic and visuospatial working memory. Effects may be mediated by high dietary fibre content and increased abundance of short-chain fatty acid producing gut bacteria. Longer follow-up with repeated measures of cognition will determine whether diet can influence changes in cognition occurring in older age., (© 2024. The Author(s).)

Introduction: Undernutrition leading to unplanned weight loss is common in older age and has been linked to increased dementia risk in later life. Weight loss can precede dementia by a decade or more, providing a unique opportunity for early intervention to correct undernutrition and potentially prevent or delay cognitive impairment. The combined effects of diet and exercise on undernutrition have not yet been evaluated. The objective of this trial is to determine the effect of a protein-enriched Mediterranean diet, with and without exercise, on nutritional status and cognitive performance in older adults at risk of undernutrition and cognitive decline., Methods: One hundred and five participants aged 60 years and over at risk of undernutrition and with subjective cognitive decline will be recruited to participate in a 6-month, single-blind, parallel-group randomised controlled trial. Participants will be block randomised into one of three groups: group 1-PROMED-EX (diet+exercise), group 2-PROMED (diet only) and group 3-standard care (control). The primary outcome is nutritional status measured using the Mini Nutritional Assessment. Secondary outcomes include cognitive function, nutritional intake, body composition, physical function and quality of life. Mechanistic pathways for potential diet and exercise-induced change in nutritional status and cognition will be explored by measuring inflammatory, metabolic, nutritional and metabolomic biomarkers., Ethics and Dissemination: The study is approved by the UK Office for Research Ethics Committee (ref: 21/NW/0215). Written informed consent will be obtained from participants prior to recruitment. Research results will be disseminated to the public via meetings and media and the scientific community through conference presentations and publication in academic journals., Trial Registration Number: ClinicalTrials.gov Registry (NCT05166564)., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY. Published by BMJ.)

Aims: Type 2 diabetes is a risk factor for late-life dementia, but dementia prevention strategies have yet to be comprehensively evaluated in people with diabetes. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) demonstrated cognitive benefits of a 2-year multidomain lifestyle intervention. However, given the intensive nature of FINGER, there is uncertainty about whether it can be implemented in other high-risk populations. Our aim was to explore attitudes towards dementia risk, and barriers to an intervention based on the FINGER model in older adults with type 2 diabetes living in rural areas of Ireland., Methods: Focus groups were conducted with 21 adults (11 men and 10 women) aged 60+ years with type 2 diabetes living in border regions of north and south Ireland. Data were analysed using thematic analysis., Results: There was limited understanding of diabetes as a risk factor for late-life dementia. The main barriers to engagement with the multidomain intervention were eating foods that were not compatible with cultural norms, time and travel constraints, and perceived lack of self-efficacy and self-motivation for adopting the desired diet, exercise and computerised cognitive training (CCT) behaviours. Facilitators for intervention acceptability included the provision of culturally tailored and personalised education, support from a trusted source, and inclusion of goal setting and self-monitoring behavioural strategies., Conclusions: While there was high acceptability for a brain health intervention, several barriers including cultural food norms and low self-efficacy for adopting the diet, exercise and CCT components would need to be considered in the intervention design. Findings from this study will be used to inform local decisions regarding the adaptation of FINGER for people with type 2 diabetes. The feasibility of the adapted multidomain intervention will then be evaluated in a future pilot trial., (© 2022 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.)

Dementia prevalence is a global public health concern. Adherence towards a healthy dietary pattern (DP) may reduce the risk of cognitive decline and dementia. This narrative systematic review aimed to synthesise prospective and intervention study data to evaluate the impact of a -posteriori and a -priori derived DPs on cognitive ageing, from cognitive decline to incident dementia. Ninety-three studies were included: 83 prospective studies and 10 randomised controlled trials (RCT). Most prospective studies (77%) examined a -priori DPs, with the Mediterranean diet examined most frequently. A total of 52% of prospective and 50% of RCTs reported a protective relationship between 'healthy' DPs and global cognitive decline. Overall, 59% of prospective studies reported positive associations between healthy DPs and risk of cognitive disorder. Incident cognitive disorder was examined by only one intervention study (subgroup analysis) which reported a beneficial effect of a low-fat diet on risk of probable dementia in women. Unhealthy DPs were examined less frequently ( n = 17; 21%), with 41% of these studies reporting associations between adherence and poorer cognitive outcomes. Overall, there were mixed results for healthy and unhealthy DPs on cognition, likely due to between-study heterogeneity. Standardisation of diet exposure and cognitive outcome measurement would help to reduce this. Future research would benefit from investigating effects of culturally appropriate DPs on individual cognitive domains and incident cognitive disorders in diverse and high-risk populations.

Aims: This systematic review aimed to examine whether persons with diabetes and depression had poorer cognition and higher dementia risk than persons with diabetes only. Moreover, the impact of timing, frequency of depressive episodes throughout life, and antidepressant treatment were examined., Methods: PubMed, Embase and PsycINFO were searched to obtain observational studies between August 2015 and June 2021 that examined the association between depression and cognition, mild cognitive impairment or dementia in people with diabetes. Studies published before August 2015 were retrieved from a previous systematic review. Findings were pooled using meta-analyses., Results: 10 out of 19 included articles were appropriate for the meta-analyses. Persons with diabetes and depression experienced greater declines in executive function (SMD = -0.39 (-0.69, -0.08)), language (SMD = -0.80 (-1.52, -0.09)), memory (SMD = -0.63 (-1.12, -0.14)) and overall cognition (SMD = -0.77 (-1.33, -0.20)), and greater dementia risk (HR = 1.82 (1.79, 1.85)) than persons with diabetes only. No significant differences were observed for complex attention. No studies examined the role of timing and frequency of depressive episodes and antidepressant treatment., Conclusion: In persons with diabetes, depression is associated with worse cognition and higher dementia risk. The potential mitigating effect of antidepressant treatment remains unclear., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Objective: To investigate whether dietary patterns (Mediterranean diet [MedDiet], Dietary Approaches to Stop Hypertension [DASH], and A Priori Diet Quality Score [APDQS]) during adulthood are associated with midlife cognitive performance., Methods: We studied 2,621 Coronary Artery Risk Development in Young Adults (CARDIA) participants; 45% were black, 57% were female, and mean age was 25 ± 3.5 years at baseline (year 0). Mean diet scores were calculated from diet history at baseline, year 7, and year 20 (mean age 25, 32, and 45 years, respectively). Cognitive function was assessed at years 25 and 30 (mean age 50 and 55 years, respectively). Linear models were used to examine association between tertiles of diet score and change in composite cognitive function and cognitive z scores (verbal memory [Rey Auditory Verbal Learning Test], processing speed [Digit Symbol Substitution Test], and executive function [Stroop Interference test]) and the Montreal Cognitive Assessment (MoCA) at year 30., Results: DASH was not associated with change in cognitive performance. Higher MedDiet and APDQS scores were associated with less decline in cognitive function (MedDiet: low -0.04, middle 0.03, high 0.03, p = 0.03; APDQS: low -0.04, middle -0.00, high 0.06, p < 0.01) and Stroop Interference (MedDiet: low 0.09, middle -0.06, high -0.03; APDQS: low 0.10, middle 0.01, high -0.09, both p < 0.01). Odds ratios (95% confidence interval) for poor global cognitive function (≥1 SD below mean MoCA score) comparing extreme tertiles of diet scores were 0.54 (0.39-0.74) for MedDiet, 0.48 (0.33-0.69) for APDQS, and 0.89 (0.68-1.17) for DASH., Conclusion: Greater adherence to MedDiet and APDQS dietary patterns during adulthood was associated with better midlife cognitive performance. Additional studies are needed to define the combination of foods and nutrients for optimal brain health across the life course., (© 2019 American Academy of Neurology.)

Diet has been investigated in relation to its ability to promote cognitive function. However, evidence is currently limited and has rarely been systematically reviewed, particularly in a mild cognitive impairment (MCI) population. This review examined the effect of diet on cognitive outcomes in MCI patients. A total of five databases were searched to find randomised controlled trial (RCT) studies, with diet as the main focus, in MCI participants. The primary outcome was incident dementia and/or Alzheimer's disease (AD) and secondary outcomes included cognitive function across different domains using validated neuropsychological tests. Sixteen studies met the inclusion criteria. There was a high degree of heterogeneity relating to the nature of the dietary intervention and cognitive outcomes measured, thus making study comparisons difficult. Supplementation with vitamin E (one study, n 516), ginkgo biloba (one study, n 482) or Fortasyn Connect (one study, n 311) had no significant effect on progression from MCI to dementia and/or AD. For cognitive function, the findings showed some improvements in performance, particularly in memory, with the most consistent results shown by B vitamins, including folic acid (one study, n 266), folic acid alone (one study, n 180), DHA and EPA (two studies, n 36 and n 86), DHA (one study, n 240) and flavonol supplementation (one study, n 90). The findings indicate that dietary factors may have a potential benefit for cognitive function in MCI patients. Further well-designed trials are needed, with standardised and robust measures of cognition to investigate the influence of diet on cognitive status.

Importance: Growing evidence suggests an association between sleep-disordered breathing (SDB) and cognitive decline in elderly persons. However, results from population-based studies have been conflicting, possibly owing to different methods to assess SDB or cognitive domains, making it difficult to draw conclusions on this association., Objective: To provide a quantitative synthesis of population-based studies on the relationship between SDB and risk of cognitive impairment., Data Sources: PubMed, EMBASE, and PsychINFO were systematically searched to identify peer-reviewed articles published in English before January 2017 that reported on the association between SDB and cognitive function., Study Selection: We included cross-sectional and prospective studies with at least 200 participants with a mean participant age of 40 years or older., Data Extraction and Synthesis: Data were extracted independently by 2 investigators. We extracted and pooled adjusted risk ratios from prospective studies and standard mean differences from cross-sectional studies, using random-effect models. This meta-analysis followed the PRISMA guidelines and also adhered to the MOOSE guidelines., Main Outcomes and Measures: Cognitive outcomes were based on standard tests or diagnosis of cognitive impairment. Sleep-disordered breathing was ascertained by apnea-hypopnea index or clinical diagnosis., Results: We included 14 studies, 6 of which were prospective, covering a total of 4 288 419 men and women. Pooled analysis of the 6 prospective studies indicated that those with SDB were 26% (risk ratio, 1.26; 95% CI, 1.05-1.50) more likely to develop cognitive impairment, with no evidence of publication bias but significant heterogeneity between studies. After removing 1 study that introduced significant heterogeneity, the pooled risk ratio was 1.35 (95% CI, 1.11-1.65). Pooled analysis of the 7 cross-sectional studies suggested that those with SDB had slightly worse executive function (standard mean difference, -0.05; 95% CI, -0.09 to 0.00), with no evidence of heterogeneity or publication bias. Sleep-disordered breathing was not associated with global cognition or memory., Conclusions and Relevance: Sleep-disordered breathing is associated with an increased risk of cognitive impairment and a small worsening in executive function. Further studies are required to determine the mechanisms linking these common conditions and whether treatment of SDB might reduce risk of cognitive impairment.