Inflammatory potential of diet is associated with cognitive function in an older adult Korean population

The Association Between Diets With High Inflammatory Potential and Sleep Quality and Its Parameters: A Systematic Review

CONTEXT

Dietary components or its overall properties can influence an individual's sleep status.

OBJECTIVE

The aim for this study was to critically search, appraise, and synthesize research evidence on the association between dietary inflammatory index (DII) and sleep quality and its parameters.

DATA SOURCES

Original published studies on adults were obtained from the PubMed, SCOPUS, ScienceDirect, Cochrane Library, and Google Scholar databases.

DATA EXTRACTION

The search was conducted without date limitation until April 2023. Duplicated and irrelevant investigations were screened out, and the results of the remaining articles were descriptively summarized, then critically appraised and analyzed. Possible mechanistic pathways regarding diet, systemic inflammation, and sleep status were discussed.

DATA ANALYSIS

Of the 102 studies searched, 23 articles (n = 4 cohort studies, 18 cross-sectional studies, and 1 intervention study) were included in the final review. The association between DII and sleep status was investigated subjectively in 21 studies and objectively in 6 studies. The main studied sleep outcomes were sleep quality, duration, latency, efficiency, apnea, disturbances, the use of sleeping medications, daytime dysfunctions, wakefulness after sleep onset, and rapid eye movement.

CONCLUSIONS

According to most of the evidence, DII may not be related to overall sleep quality, sleep duration, latency, efficiency, and the use of sleeping medications. The evidence of positive association was greater between a high DII score (pro-inflammatory diet) with daytime dysfunctions, wakefulness after sleep onset, and sleep apnea. There is insufficient evidence to make any conclusion regarding sleep disturbances and rapid eye movement.

Dietary Inflammatory Index and Cognitive Function: Findings from a Cross-Sectional Study in Obese Chinese Township Population from 45 to 75 Years

Background and Objective

Cognitive dysfunction is highly prevalent in obese people, and food is a key factor in obesity, and dietary inflammatory index (DII) can reflect whether diet has anti-inflammatory or pro-inflammatory potential. In addition, dietary fatty acid consumption is linked to inflammation, obesity, and cognitive impairment. Erythrocyte membrane fatty acids can reflect dietary fatty acid intake. Our hypothesis was that erythrocyte membrane fatty acids might have a significant impact on the relationship between DII and cognition in obese individuals, and we designed experiments to test the hypothesis.

Methods

In three villages in Beijing, we collected 579 respondents from individuals 45 to 75 years old and categorized them by body mass index. The Montreal Cognitive Assessment (MoCA) score and DII score was calculated and gas chromatography was used to measure the proportion of erythrocyte membrane fatty acids. The relationship between the DII score and cognition was examined using multiple linear regression and binary logistic regression. Mediation analysis can help to understand the causal chain between variables, deeply explore the internal relationship and mechanism of action between variables. So a multiple chain mediation model was developed to investigate the mediating factors between the DII score and cognitive association.

Results

According to adjusted linear regression, higher DII scores were linked to lower MoCA scores in the obese group. The negative correlation between DII score and cognitive function score remains in binary linear regression. We discovered through mediation analysis that erythrocyte membrane fatty acids mediate the detrimental link between DII and cognitive function in obese individuals.

Conclusion

We propose that higher DII scores in obese people are associated with a decline in cognitive function. In addition, this effect might be mediated via the fatty acids in the erythrocyte membrane.

Dietary inflammatory index and neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are considered a potential threat to mental health. Inflammation predominantly plays a role in the pathophysiology of NPDs. Dietary patterns are widely postulated to be involved in the physiological response to inflammation. This review aims to discuss the literature on how dietary inflammatory index (DII) is related to inflammation and, consequently, NPDs. After comprehensive scrutiny in different databases, the articles that investigated the relation of DII score and various NPDs and psychological circumstances were included. The association between dietary patterns and mental disorders comprising depression, anxiety, and stress proved the role of a proinflammatory diet in these conditions' exacerbation. Aging is another condition closely associated with DII. The impact of proinflammatory and anti-inflammatory diet on sleep quality indicated related disorders like sleep latency and day dysfunctions among the different populations are in relation with the high DII score. The potential effects of genetic backgrounds, dietary patterns, and the gut microbiome on DII are discussed as well. To plan preventive or therapeutic interventions considering the DII, these factors, especially genetic variations, should be considered as there is a growing body of literature indicating the role of personalized medicine in different NPDs. To the best of our knowledge, there is a limited number of RCTs on this subject, so future research should evaluate the causality via RCTs and look for therapeutic interventions with an eye on personalized medicine using information about DII in NPDs.

Energy-adjusted dietary inflammatory index and cognitive function in Chinese older adults: a population-based cross-sectional study

Diet can regulate systemic inflammation, which may play an important role in the development and progression of cognitive impairment and dementia. To explore the relationship between the dietary inflammatory potential and cognitive ability. A total of 2307 adults aged 60 years or older were recruited from the Fujian Provincial Hospital (Fujian, China). Dietary inflammatory properties were analyzed using the energy-adjusted dietary inflammatory index (E-DII). The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to assess cognitive function. Logistic regression and restricted cubic spline (RCS) were fit to assess the associations between variables. The MCI subjects with the highest E-DII scores had a higher risk of AD compared to subjects with the lowest E-DII scores (OR = 1.98, 95%CI = 1.49-2.64, P for trend < 0.001). Subjects with the highest E-DII levels were at increased risk of cognitive impairment compared to those with the lowest E-DII levels (OR = 1.56, 95%CI = 1.25-1.93, P for trend < 0.001). The link between E-DII and cognitive impairment was significant in a nonlinear dose response analysis (P for nonlinear = 0.001). Higher E-DII scores were associated with an increased risk of developing AD or cognitive impairment. These findings may contribute to the effective prevention of cognitive impairment by constructing a multidisciplinary synergistic prevention strategy and controlling dietary inflammation levels.

Association between dietary inflammatory index score and incident dementia: results from the Framingham heart Study offspring cohort

Background

The Dietary Inflammatory Index (DII), has been specifically designed to capture the inflammatory content of diet and has shown association with neurodegenerative disease related outcomes. But literature is limited on the role of diet-driven inflammation measured by the DII on incident all-cause dementia and Alzheimer's disease dementia (AD).

Objective

We evaluated whether higher DII scores were associated with increased incidence of all-cause dementia and AD over 22.3 years of follow-up in the community-based Framingham Heart Study (FHS) Offspring cohort.

Design Setting and Participants

Observational longitudinal study in the FHS Offspring cohort. Dementia surveillance for present study: until 2020. Data were analyzed from December 2020 to June 2022. Participants completed a validated 126-item food frequency questionnaires (FFQ), administered at FHS examination cycle 7 (1998-2001) and examination cycle 5 (1991-1995), and/or 6 (1995-1998). Individuals aged <60 years, with prevalent dementia, no dementia follow-up, other relevant neurological diseases, and/or no FFQ data were excluded.

Exposure

A DII score (based on the published method by Shivappa et al. 2014) was created based on previous studies linking individual dietary factors to six inflammatory markers (i.e. C-reactive protein, interleukin (IL)-1β, IL-4, IL-6, IL-10, and tumor necrosis factor-alpha), consisting of 36 components. A cumulative DII score was calculated by averaging across a maximum of three FFQs.

Main outcomes and measures

Incident all-cause dementia and AD.

Results

We included 1487 participants (mean±SD, age in years 69 ± 6; 53·2% women; 31·6% college graduates]). 246 participants developed all-cause dementia (including AD n=187) over a median follow up time of 13·1 years. Higher DII scores were associated with an increased incidence of all-cause dementia and AD following adjustment for age and sex (Hazard ratio (HR) 1·16, 95% confidence interval (CI) 1·07 to 1·25, p<.001; HR 1·16, 95% CI 1·06 to 1·26, p=.001). The relationships remained after additional adjustment for demographic, lifestyle, and clinical covariates (HR 1·21, 95% CI 1·10 to 1·33, p<0.001; HR1·20, 95% CI1·07 to 1·35, p=.001).

Conclusion and relevance

Higher DII scores were associated with a higher risk of incident all-cause dementia and AD. Although these promising findings need to be replicated and further validated, our results suggest that diets which correlate with low DII scores may prevent late-life dementia.

Association of pro-inflammatory diet with increased risk of all-cause dementia and Alzheimer's dementia: a prospective study of 166,377 UK Biobank participants

BACKGROUND

Increasing evidence suggests an association between pro-inflammatory diets and cognitive function. However, only a few studies based on small sample sizes have explored the association between pro-inflammatory diets and dementia using the dietary inflammatory index (DII). Additionally, the relationship between DII and different subtypes of dementia, such as Alzheimer's dementia and vascular dementia, remains largely unexplored. Given the changes in brain structure already observed in patients with dementia, we also investigated the association between DII and magnetic resonance imaging (MRI) measures of brain structure to provide some hints to elucidate the potential mechanisms between pro-inflammatory diet and cognitive decline.

METHODS

A total of 166,377 UK Biobank participants without dementia at baseline were analyzed. DII calculations were based on the information collected by the 24-h recall questionnaire. Brain structural anatomy and tissue-specific volumes were measured using brain MRI. Cox proportional hazards models, competing risk models, and restricted cubic spline were applied to assess the longitudinal associations. The generalized linear model was used to assess the association between DII and MRI measurements.

RESULTS

During a median follow-up time of 9.46 years, a total of 1372 participants developed dementia. The incidence of all-cause dementia increased by 4.6% for each additional unit of DII [hazard ratio (HR): 1.046]. Besides, DII displayed a "J-shaped" non-linear association with Alzheimer's dementia (P_nonlinear = 0.003). When DII was above 1.30, an increase in DII was significantly associated with an increased risk of Alzheimer's dementia (HR: 1.391, 95%CI: 1.085-1.784, P = 0.009). For brain MRI, the total volume of white matter hyperintensities increased with an increase in DII, whereas the volume of gray matter in the hippocampus decreased.

CONCLUSIONS

In this cohort study, higher DII was associated with a higher risk of all-cause dementia and Alzheimer's dementia. However, our findings suggested that the association with DII and vascular and frontotemporal dementia was not significant.

Plasma proteins related to inflammatory diet predict future cognitive impairment

Dysregulation of the immune system and dietary patterns that increase inflammation can increase the risk for cognitive decline, but the mechanisms by which inflammatory nutritional habits may affect the development of cognitive impairment in aging are not well understood. To determine whether plasma proteins linked to inflammatory diet predict future cognitive impairment, we applied high-throughput proteomic assays to plasma samples from a subset (n = 1528) of Women's Health Initiative Memory Study (WHIMS) participants (mean [SD] baseline age, 71.3 [SD 3.8] years). Results provide insights into how inflammatory nutritional patterns are associated with an immune-related proteome and identify a group of proteins (CXCL10, CCL3, HGF, OPG, CDCP1, NFATC3, ITGA11) related to future cognitive impairment over a 14-year follow-up period. Several of these inflammatory diet proteins were also associated with dementia risk across two external cohorts (ARIC, ESTHER), correlated with plasma biomarkers of Alzheimer's disease (AD) pathology (Aβ42/40) and/or neurodegeneration (NfL), and related to an MRI-defined index of neurodegenerative brain atrophy in a separate cohort (BLSA). In addition to evaluating their biological relevance, assessing their potential role in AD, and characterizing their immune-tissue/cell-specific expression, we leveraged published RNA-seq results to examine how the in vitro regulation of genes encoding these candidate proteins might be altered in response to an immune challenge. Our findings indicate how dietary patterns with higher inflammatory potential relate to plasma levels of immunologically relevant proteins and highlight the molecular mediators which predict subsequent risk for age-related cognitive impairment.

Higher Dietary Inflammatory Index scores are associated with brain MRI markers of brain aging: Results from the Framingham Heart Study Offspring cohort

INTRODUCTION

We investigated cross-sectional associations between the Dietary Inflammatory Index (DII) and measures of brain volume and cerebral small vessel disease among participants of the Framingham Heart Study Offspring cohort.

METHODS

A total of 1897 participants (mean ± standard deviation, age 62±9) completed Food Frequency Questionnaires and brain magnetic resonance imaging (MRI).

RESULTS

Higher (pro-inflammatory) DII scores, averaged across a maximum of three time points, were associated with smaller total brain volume (beta ± standard error: -0.16 ± 0.03; P < .0001) after adjustment for demographic, clinical, and lifestyle covariates. In addition, higher DII scores were associated with smaller total gray matter volume (-0.08 ± 0.03; P = .003) and larger lateral ventricular volume (0.04 ± 0.02; P = .03). No associations were observed with other brain MRI measures.

DISCUSSION

Our findings showed associations between higher DII scores and global brain MRI measures. As we are one of the first groups to report on the associations between higher DII scores and brain volume, replication is needed to confirm our findings.

Association between dietary inflammatory index and cognitive impairment: A meta-analysis

Aims

Cognitive impairment is an increasingly urgent global public health challenge. Dietary Inflammatory Index (DII) is a literature-derived score that links diet to inflammation. The relationship between DII and cognitive impairment remains controversial. Therefore, our study aimed to analysis the role of DII on the risk of cognitive impairment by meta-analysis.

Methods

PubMed, Cochrane Library, MEDLINE, Web of Science and EMBASE databases were searched up to July 2022. Newcastle-Ottawa scale (NOS) and Joanna Briggs Institute (JBI) Checklist were performed to estimate the quality of studies.

Results

Nine observational studies with 19,379 subjects were included. Our study found that higher DII could elevate the risk of cognitive impairment (OR = 1.46, 95%CI = 1.26, 1.69). Meanwhile, the OR of cognitive impairment was 1.49 (95%CI = 1.21, 1.83) for cross-sectional studies and 1.42 (95%CI = 1.12, 1.79) for cohort studies, respectively.

Conclusion

Our meta-analysis indicated that higher DII (indicating a more pro-inflammatory diet) is related to increased risk of cognitive impairment.

Associations between dietary and blood inflammatory indices and their effects on cognitive function in elderly Americans

Objective

To determine the correlations between dietary and blood inflammation indices in elderly Americans and their effects on cognitive function.

Methods

This research extracted data from the 2011-2014 National Health and Nutrition Examination Survey for 2,479 patients who were ≥60 years old. Cognitive function was assessed as a composite cognitive function score (Z-score) calculated from the results of the Consortium to Establish a Registry for Alzheimer's Disease Word Learning and Delayed Recall tests, the Animal Fluency test, and the Digit Symbol Substitution Test. We used a dietary inflammatory index (DII) calculated from 28 food components to represent the dietary inflammation profile. Blood inflammation indicators included the white blood cell count (WBC), neutrophil count (NE), lymphocyte count (Lym), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), neutrophil-albumin ratio (NAR), systemic immune-inflammation index [SII, calculated as (peripheral platelet count) × NE/Lym], and systemic inflammatory response index [SIRI, calculated as (monocyte count) × NE/Lym]. WBC, NE, Lym, NLR, PLR, NAR, SII, SIRI, and DII were initially treated as continuous variables. For logistic regression, WBC, NE, Lym, NLR, PLR, NAR, SII, and SIRI were divided into quartile groups, and DII was divided into tertile groups.

Results

After adjusting for covariates, WBC, NE, NLR, NAR, SII, SIRI, and DII scores were markedly higher in the cognitively impaired group than in the normal group (p < 0.05). DII was negatively correlated with the Z-score when combined with WBC, NE, and NAR (p < 0.05). After adjusting for all covariates, DII was positively correlated with SII in people with cognitive impairment (p < 0.05). Higher DII with NLR, NAR, SII, and SIRI all increased the risk of cognitive impairment (p < 0.05).

Conclusion

DII was positively correlated with blood inflammation indicators, and higher DII and blood inflammation indicators increased the risk of developing cognitive impairment.

Meta-analysis of the association between dietary inflammatory index and cognitive health

Background

Some studies have shown that a pro-inflammatory diet may be associated with cognitive function, but their conclusions have varied considerably. We here present a meta-analysis of the current published literature on DII score and its association with cognitive health.

Methods

In this meta-analysis, the PubMed, Embase, Web of Science, and Cochrane databases were searched in September 2022. The reported indexes, specifically OR, RR, and β, were extracted and analyzed using R version 3.1.0.

Results

A total of 636 studies in databases were identified, and 12 were included in the meta-analysis. Higher DII was associated with an increased risk of AD and MCI (OR = 1.34; 95% CI = 1.21-1.49). Meanwhile, it may also cause global function impairment (categorical: OR = 1.63; 95% CI = 1.36-1.96) and verbal fluency impairment (continuous: OR = 0.18; 95% IC = 0.08-0.42). But there was no significant association between DII and executive function (categorical: OR = 1.12; 95% IC = 0.84-1.49; continuous: OR = 0.48; 95% IC = 0.19-1.21) or episodic memory (continuous: OR = 0.56; 95% IC = 0.30-1.03).

Conclusion

A pro-inflammatory diet is related to AD, MCI, and the functions of some cognitive domains (specifically global function and verbal fluency). However, the current evidence on the role of diet-induced inflammation in different cognitive domains should be supported by further studies in the future.

Association of dietary inflammatory index and leukocyte telomere length with mild cognitive impairment in Chinese older adults

BACKGROUND

There are minimal data on the relationship between DII and MCI in an elderly Chinese population and no research has assessed the potential effect of LTL.

OBJECTIVE

We investigated the association between DII and MCI while taking into account the potential effect of LTL.

METHODS

This cross-sectional study included 3,386 participants aged ≥ 60 years of age from the Tianjin Elderly Nutrition and Cognition Cohort study. DII score was constructed based on a validated self-administered food frequency questionnaire was calculated based on the method developed by Shivappa et al. LTL was measured by quantitative real-time polymerase chain reaction. Multivariable logistic regression analysis was used to analyze the association between DII, LTL and MCI. Moreover, mediation analysis was employed to test the mediation effect of LTL on the total effect of DII on MCI.

RESULTS

Compared with the participants in the lowest tertiles of LTL and DII score, the odds ratios (ORs) of MCI in the highest tertiles were 0.386(95% CI: 0.281-0.529) and 1.650 (95% CI: 1.232-2.209), respectively. The significant association between DII score and MCI persisted after further adjusting for LTL (OR: 1.595; 95% CI: 1.189-2.140). The link between DII score and MCI was mediated partially by LTL (βindirect effect= -0.008, P<0.05).

CONCLUSION

High DII score was positively associated with MCI prevalence in an elderly Chinese population and the link between DII scores and MCI seemed to be mediated partially by LTL.

Neuroinflammation in Dementia—Therapeutic Directions in a COVID-19 Pandemic Setting

Although dementia is a heterogenous group of diseases, inflammation has been shown to play a central role in all of them and provides a common link in their pathology. This review aims to highlight the importance of immune response in the most common types of dementia. We describe molecular aspects of pro-inflammatory signaling and sources of inflammatory activation in the human organism, including a novel infectious agent, SARS-CoV-2. The role of glial cells in neuroinflammation, as well as potential therapeutic approaches, are then discussed. Peripheral immune response and increased cytokine production, including an early surge in TNF and IL-1β concentrations activate glia, leading to aggravation of neuroinflammation and dysfunction of neurons during COVID-19. Lifestyle factors, such as diet, have a large impact on future cognitive outcomes and should be included as a crucial intervention in dementia prevention. While the use of NSAIDs is not recommended due to inconclusive results on their efficacy and risk of side effects, the studies focused on the use of TNF antagonists as the more specific target in neuroinflammation are still very limited. It is still unknown, to what degree neuroinflammation resulting from COVID-19 may affect neurodegenerative process and cognitive functioning in the long term with ongoing reports of chronic post-COVID complications.

Association between Dietary Patterns and the Risk of Depressive Symptoms in the Older Adults in Rural China

Geriatric depression, a chronic condition, has become a substantial burden in rural China. This study aimed to assess the association between dietary patterns and the risk of geriatric depression in rural China. Between March 2018 and June 2019, 3304 participants were recruited for this cross-sectional study in rural Tianjin, China. Principal component analysis was used to determine the major dietary patterns. The associations between dietary patterns and the risk of geriatric depression were assessed using a logistic regression model. Four dietary patterns were identified: vegetables-fruit, animal food, processed food, and milk-egg. The study found that vegetable-fruit (Q2 vs. Q1: OR = 0.62, 95% CI: 0.46–0.83; Q3 vs. Q1: OR = 0.54, 95% CI: 0.38–0.75; Q4 vs. Q1: OR = 0.39, 95% CI: 0.26–0.57) and animal food patterns (Q3 vs. Q1: OR = 0.69, 95% CI: 0.50–0.95; Q4 vs. Q1: OR = 0.58, 95% CI: 0.41–0.82) were associated with a decreased risk of depression, and inflammatory dietary pattern (Q2 vs. Q1: OR = 1.71, 95% CI: 1.23–2.38; Q3 vs. Q1: OR = 1.70, 95% CI: 1.22–2.36; Q4 vs. Q1: OR = 1.44, 95% CI: 1.03–2.03) was associated with an increased risk of depression. The present findings reinforce the importance of adopting an adequate diet consisting of vegetables, fruit and animal foods, while limiting the intake of pro-inflammatory foods, to decrease the risk of depression.

APOE gene region methylation is associated with cognitive performance in middle-aged urban adults

Apolipoprotein (APOE) ε4 allele is a strong risk factor for Alzheimer's disease (AD) and cognitive decline. Epigenetic modifications such as DNA methylation (DNAm) play a central role in cognition. This study sought to identify DNAm sites in the APOE genomic region associated with cognitive performance in a racially diverse middle-aged cohort (n = 411). Cognitive performance was measured by 11 standard neuropsychological tests. Two CpG sites were associated with the Card Rotation and Benton Visual Retention cognitive tests. The methylation level of the CpG site cg00397545 was associated with Card Rotation Test score (p = 0.000177) and a novel CpG site cg10178308 was associated with Benton Visual Retention Test score (p = 0.000084). Significant associations were observed among the dietary inflammatory index, which reflects the inflammatory potential of the diet, cognitive performance and the methylation level of several CpG sites. Our results indicate that DNAm in the APOE genomic area is correlated with cognitive performance and may presage cognitive decline.

Empirical Dietary Inflammatory Pattern Scores Are Not Associated with Worse Cognitive Performance in the Nurses' Health Study

BACKGROUND

Low-grade chronic inflammation associated with unhealthy diets may lead to cognitive aging.

OBJECTIVES

We evaluated whether higher long-term adherence to an empirical dietary inflammatory pattern (EDIP) was associated with lower cognitive function after age 70 y in the Nurses' Health Study.

METHODS

A total of 16,058 older (mean ± SD age: 74 ± 2 y) highly educated (≥ bachelor degree) White women completed up to 5 validated 116-item food-frequency questionnaires. An EDIP score, previously derived with the use of reduced rank regression to predict circulating inflammatory markers (i.e., C-reactive protein, TNF-α receptor 2, and IL-6), was computed based on 9 anti-inflammatory and 9 proinflammatory components. A long-term EDIP score was calculated by averaging across 5 exams. The EDIP score was categorized into quintiles, taking the first (anti-inflammatory) quintile as the reference category. Cognitive testing was performed through telephone interviews over 4 follow-up exams (1995-2008). A composite global cognition score, a composite verbal memory score, and the Telephone Interview for Cognitive Status (TICS) were calculated and averaged across the 4 exams (6 y of follow-up). Multivariable linear regressions were used to examine longitudinal relations under study.

RESULTS

Higher long-term EDIP scores (i.e., more proinflammatory) were significantly associated with worse performance on global cognitive function (P-trend= 0.018) and TICS (P-trend= 0.004) after adjustment for demographic and lifestyle factors. The associations became nonsignificant after additional adjustments for disease (related) risk factors for dementia. No association was observed between the EDIP score and verbal memory.

CONCLUSIONS

We observed no relation between long-term EDIP scores and averaged global cognitive function and verbal memory among older women. Our findings suggest no relation between long-term adherence to a proinflammatory diet and cognitive function in a large population of mostly White and generally highly educated older women. Future studies are encouraged to investigate the relation between inflammatory diets and cognitive function in other races/ethnicities and men, and over a longer follow-up period.

Association of Dietary Inflammatory Potential with Blood Inflammation: The Prospective Markers on Mild Cognitive Impairment

Inflammation is known as an important mechanism of cognitive dysfunction. Systemic immune inflammation index (SII) and system inflammation response index (SIRI) are two blood inflammatory markers, which are related to many chronic diseases including cognitive impairment. It is recognized that dietary inflammatory index (DII), which is used to estimate the overall inflammatory potential of diet, may be related to mild cognitive impairment (MCI) as well. This study aimed to explore the relationship between SII, SIRI and DII, as well as the role of these inflammatory indexes on MCI in elderly people. A total of 1050 participants from Beijing were included. Neuropsychological tests were used for cognitive evaluation. Energy-adjusted DII scores were calculated based on semi-quantitative food frequency questionnaire. Blood samples were tested for calculating SII and SIRI. Log-binomial regression models were used to estimate the correlation of indexes. After adjusting demographic characteristics, SII and SIRI in MCI individuals were higher than controls (p ≤ 0.001). DII, SII and SIRI had positive relationship with MoCA scores (p < 0.005). DII also correlated with SIRI in MCI (β = 0.11, p = 0.031). Higher DII and SIRI could definitely increase the risk of MCI, as well as DII and SII (p < 0.005). In conclusion, DII was positively correlated with blood inflammation. The elderly with higher level of DII and SIRI, or DII and SII could be considered as people with higher risk of developing MCI.

The Association Between Dietary Inflammatory Index and Cognitive Performance in Older Adults Aged 60 Years and Older

Background

Neuroinflammation has been linked to the development of cognitive performance. Epidemiological evidence on dietary inflammatory potential and cognitive performance is scarce. We evaluated the association between dietary inflammatory index (DII) and cognitive performance in older adults.

Methods

This study included adults aged 60 years or older from the 2011–2014 National Health and Nutrition Examination Survey. The DII scores were calculated based on 27 nutritional parameters. Cognitive performance was assessed with four cognitive tests: the Digit Symbol Substitution Test (DSST, n = 2,780), the Consortium to Establish a Registry for Alzheimer’s Disease Word Learning (CERAD-WL, n = 2,859) and Delayed Recall (CERAD-DR, n = 2,857), and the Animal Fluency (AF, n = 2,844) tests. Restricted cubic splines and logistic regression were adopted to assess the associations.

Results

Comparing the highest to lowest tertile of DII scores, the odds ratio (95% CI) of lower cognitive functioning was 1.97 (1.08–3.58) [P-trend = 0.02, per 1 unit increment: 1.17 (1.01–1.38)] on DSST, 1.24 (0.87–1.76) [P-trend = 0.24, per 1 unit increment: 1.09 (0.96–1.23)] on CERAD-WL, 0.93 (0.57–1.51) [P-trend = 0.74, per 1 unit increment: 1.02 (0.87–1.20)] on CERAD-DR, and 1.76 (1.30–2.37) [P-trend < 0.01, per 1 unit increment: 1.17 (1.05–1.29)] on AF. The above-mentioned associations were observed in both men and women. In non-linear dose–response analysis, the association between DII and lower cognitive functioning was not significant at lower DII scores up to 3.0, after which the association was significant and the curve rose steeply.

Conclusion

Higher DII is associated with lower scores on DSST and AF tests in older adults.

The Association Among Inflammatory Diet, Glycohemoglobin, and Cognitive Function Impairment in the Elderly: Based on the NHANES 2011–2014

Background: Dietary inflammatory index (DII) was associated with Type 2 diabetes mellitus and cognitive function impairment (CFI). Objective: The aim of this study was to explore whether the associations among DII, glycohemoglobin (HbA1c), and CFI were similar in the participants with or without diabetes. Methods: A total of 1,198 participants aged 60 and over from the National Health and Nutrition Examination Survey (NHANES) in 2011–2014 were involved in this study, dividing into subgroups as diabetes and non-diabetes for further analysis. Results: We found that participants with pro-inflammatory diet had higher proportion of CFI patients (p <  0.05). Pro-inflammatory diet and HbA1c were positively associated with the risk of CFI; participants with pro-inflammatory diet was 1.479 times on occurrence of CFI compared with anti-inflammatory diet group. The interaction between inflammatory diet and HbA1c was positive on the risk of CFI and was negative on the CERAD-immediate and CERAD-delayed, respectively. Among the participants without diabetes, the associations of Energy-adjusted DII (E-DII) with Animal Fluency test and Digit Symbol Substitution Test (DSST) were partially mediated by HbA1c, and the mediated proportion was 5.8% and 6.6%, respectively. However, there was no such mediation effect in the diabetes patients. Conclusion: In elderly participants without diabetes, there was an interaction between inflammatory diet and HbA1c on the association with CFI, especially for the dimension of CERAD-immediate and CERAD-delayed. Besides, the associations of E-DII with Animal Fluency test and DSST were partially mediated by HbA1c. For diabetic patients, HbA1c, rather than the inflammatory diet has a positive effect on the CFI risk.

Dietary Inflammatory Index score and prodromal Parkinson's disease incidence: The HELIAD study

AIM

The aim of the present study was to investigate the association of the inflammatory potential of diet with prodromal Parkinson's disease (pPD) probability and incidence among community-dwelling older individuals without clinical features of parkinsonism at baseline.

METHODS

The sample consisted of 1,030 participants 65 years old or older, drawn from a population-based cohort study of older adults in Greece (Hellenic Longitudinal Investigation of Aging and Diet - HELIAD). We calculated pPD probability, according to International Parkinson and Movement Disorder Society research criteria. Dietary Inflammatory Index (DII) was used to measure the dietary inflammatory potential, with higher index score reflecting a more pro-inflammatory diet. Associations of baseline DII with pPD probability cross-sectionally, and with possible/probable pPD incidence (pPD probability ≥30%) during the follow-up period, were examined via general linear models and generalized estimating equations, respectively.

RESULTS

Cross-sectionally, one unit increase of DII score[DII (min, max) = -5.83, 6.01]was associated with 4.9% increased pPD probability [β=0.049, 95%CI (0.025-0.090), p<0.001]. Prospectively, 62 participants developed pPD during 3.1±0.9 (mean±SD) years of follow-up. One unit increase in DII was associated with 20.3% increased risk for developing pPD [RR=1.203, 95%CI (1.070-1.351), p=0.002]. Participants in the highest tertile of DII score were 2.6 times more likely to develop pPD [β=2.594, 95%CI (1.332-5.050), p=0.005], compared to those in the lowest tertile.

CONCLUSION

More pro-inflammatory diet was related with higher pPD probability and pPD incidence (pPD probability ≥30%) in a community-dwelling older adult population. Further studies are needed to confirm these findings.

Associations between potential inflammatory properties of the diet and frequency, duration, and severity of migraine headaches: a cross-sectional study

Despite a large body of literature on the association between the dietary inflammatory index (DII) and various chronic diseases, limited knowledge is available regarding the association between DII and migraine. Therefore, we assessed the relationship between the DII and migraine characteristics, including duration, frequency, and severity of migraine headaches, Headache Impact Test-6 (HIT-6), and serum levels of nitric oxide (NO). This population-based cross-sectional study was conducted from August 2019 to June 2020 among 262 patients (38 men and 224 women; 20–50 years). A 168-item semiquantitative food frequency questionnaire (FFQ) was gathered to evaluate dietary intake, and subsequently, an energy-adjusted DII score was calculated. After controlling for potential confounders, an increase of 3.48 in headache frequency was observed when the DII score increased from − 4.04 to − 1.83 (β = 3.48; 95% CI 1.43, 5.54). In the crude model, headache duration tended to be inversely associated with DII in the subjects with the pro-inflammatory diet compared to those with the anti-inflammatory diet (β = − 0.22; 95% CI − 0.46, 0.02). After adjustment for confounders, those with the highest DII values were at a higher risk of severe headaches than those with the lowest values (OR = 2.25; 95% CI 1.17, 4.32). No other significant results were found in terms of the association between DII and HIT-6 or serum NO levels. We found evidence suggesting that higher adherence to a diet with anti-inflammatory properties was significantly and inversely related to headache frequency. Furthermore, our results suggest that the DII score is substantially related to migraine severity.

Memory and eating: A bidirectional relationship implicated in obesity

This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.

Diet Inflammatory Index and Dementia Incidence: A Population-Based Study

BACKGROUND AND OBJECTIVES

Aging is characterized by a functional shift of the immune system toward a proinflammatory phenotype. This derangement has been associated with cognitive decline and has been implicated in the pathogenesis of dementia. Diet can modulate systemic inflammation; thus, it may be a valuable tool to counteract the associated risk for cognitive impairment and dementia. The present study aimed to explore the associations between the inflammatory potential of diet, assessed with an easily applicable, population-based, biomarker-validated diet inflammatory index (DII), and the risk for dementia in community-dwelling older adults.

METHODS

Individuals from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) were included in the present cohort study. Participants were recruited through random population sampling and were followed up for a mean of 3.05 (standard deviation 0.85) years. Dementia diagnosis was based on standard clinical criteria. Those with baseline dementia or missing cognitive follow-up data were excluded from the analyses. The inflammatory potential of diet was assessed through a DII score that considers literature-derived associations of 45 food parameters with levels of proinflammatory and anti-inflammatory cytokines in the blood; higher values indicated a more proinflammatory diet. Consumption frequencies were derived from a detailed food frequency questionnaire and were standardized to representative dietary intake normative data from 11 different countries. Analysis of dementia incidence as a function of baseline DII scores was performed by Cox proportional hazards models.

RESULTS

Analyses included 1,059 individuals (mean age 73.1 years, 40.3% male, mean education 8.2 years), 62 of whom developed incident dementia. Each additional unit of DII score was associated with a 21% increase in the risk for dementia incidence (hazard ratio 1.21 [95% confidence interval 1.03-1.42]; p = 0.023). Compared to participants in the lowest DII score tertile, participants in the highest one (maximal proinflammatory diet potential) were 3 (95% confidence interval 1.2-7.3; p = 0.014) times more likely to develop incident dementia. The test for trend was also significant, indicating a potential dose-response relationship (p = 0.014).

DISCUSSION

In the present study, higher DII scores (indicating greater proinflammatory diet potential) were associated with an increased risk for incident dementia. These findings might avail the development of primary dementia preventive strategies through tailored and precise dietary interventions.

Diet quality, gut microbiota, and microRNAs associated with mild cognitive impairment in middle-aged and elderly Chinese population

BACKGROUND

Diet, the gut microbiota, and microRNAs (miRNAs) have been recognized as factors possibly influencing the pathogenesis of Alzheimer's disease. However, the combined role of diet, the gut microbiota, and miRNAs in mild cognitive impairment (MCI) has not been extensively investigated.

OBJECTIVES

To examine the associations among diet quality, the gut microbiota, miRNAs, and risks of MCI in middle-aged and elderly Chinese population.

METHODS

Participants were drawn from the Effects and Mechanism Investigation of Cholesterol and Oxysterol on Alzheimer's disease (EMCOA) study. We included 2239 participants who completed comprehensive cognitive tests and dietary surveys at baseline and follow-up. Chinese Dietary Guidelines Index 2018 (CDGI-2018), Energy-Adjusted Dietary Inflammatory Index (E-DII) and Healthy Lifestyle Score (HLS) values were calculated based on data from a standard questionnaire. Changes of gut microbiota and serum miRNA expression were detected in 75 MCI and 52 healthy participants. The receiver operating characteristic curve was performed based on a logistic regression model distinguishing patients with MCI from healthy controls.

RESULTS

Higher CDGI-2018 (RR, 0.75; 95% CI: 0.58-0.98) and HLS (RR, 0.54; 95% CI: 0.34-0.84) values and lower E-DII (RR, 1.46; 95% CI: 1.14-1.87) values were significantly associated with a lower risk of MCI. Lower microbial diversity and abundance of Faecalibacterium, unidentified Ruminococcaceae, and Alistipes were found in MCI participants compared with healthy controls. The abundance of ProteobacteriaandGammaproteobacteria was higher in MCI participants and was correlated with hsa-let-7g-5p, hsa-miR-107, and hsa-miR-186-3p. The predictive signatures of diet quality scores, differential gut microbiota, and serum miRNAs had good performance on distinguishing MCI participants from healthy individuals (AUC = 0.91).

CONCLUSIONS

A better diet quality is associated with a lower risk of MCI, which may be mediated by the microbiota composition and miRNA expression. These findings suggest that diet, the gut microbiota, and miRNAs may serve as a combinatorial biomarker to identify MCI patients and provide new insight for the diagnosis and prevention of MCI. This study was registered at the Chinese Clinical Trial Registry as ChiCTROOC-17011882.

Diet-Related Inflammation is Associated with Major Depressive Disorder in Bahraini Adults: Results of a Case-Control Study Using the Dietary Inflammatory Index

PURPOSE

This case-control study aimed to examine the association between the inflammation potential of the diet and depression.

PATIENTS AND METHODS

Ninety-six patients with major depression disorder were matched with 96 age- and sex-matched healthy controls. Energy-adjusted DII (E-DIITM) scores were calculated based on the participants' responses to a detailed nutritional assessment using a quantitative food frequency questionnaire. Descriptive results were reported. Logistic regression was used to estimate odds ratios and 95% confidence intervals associated with E-DII scores and depression adjusting for covariates including age, sex, body mass index, comorbidities, level of education, and employment.

RESULTS

The mean E-DII score of participants in the study was 1.32±1.08, indicating a generally pro-inflammatory diet. Patients with depression had elevated E-DII scores compared to age- and sex-matched controls with E-DII scores of 1.72± 1.09 vs 0.90±0.90, respectively (P=0.001). Results of logistic regression analysis revealed that patients with depression were nearly three times more likely to be in the extreme ends of pro-inflammatory diet (OR 2.75; 95% CI 1.82-4.15).

CONCLUSION

Adult Bahraini patients with depression have higher dietary inflammation potential compared to the general population controls. Further research is needed to confirm these results and provide effective interventions to reduce the burden of this dietary inflammation.

Anti-Inflammatory Diets and Schizophrenia

Schizophrenia is a mental illness characterized by symptoms such as hallucinations, delusions, disorganized speech, disorganized or catatonic behavior, and negative symptoms (emotional flatness, apathy, and lack of speech). It causes social and economic burdens to patients and their family. Although etiology of schizophrenia is still uncertain, dopamine dysregulation is traditionally considered as a main etiological factor of schizophrenia, which has been utilized to develop drugs for treating schizophrenia. Recently, inflammation has presented being a risk factor for schizophrenia in that neuroinflammation contributes to the pathophysiology of schizophrenia and the exacerbation of symptom severity. Various factors including diet can regulate inflammatory state. Specific foods or dietary patterns have anti- or pro-inflammatory potentials. Increased levels of pro-inflammatory cytokines and microglia activation have been reported in schizophrenia populations and were related to the pathogenesis of schizophrenia. Omega-3 fatty acids were often recommended to schizophrenia patients because of their anti-inflammatory activities. In this review, we investigate the inflammation-related pathogenesis of schizophrenia and summarize potential nutritional approaches to inhibit the manifestation of symptoms and to alleviate symptom severity using anti-inflammatory nutrients or functional components.

The dietary inflammatory index (DII®) and its association with cognition, frailty, and risk of disabilities in older adults: A systematic review

BACKGROUND & AIMS

Systemic inflammation is considered an important issue in older adults and is associated with adverse health outcomes, such as frailty and cognitive impairment. Diet is a critical associated factor, and the dietary inflammatory index (DII®) is proposed as a promising tool to identify the association between diet and health outcomes. Our aims were: (i) to investigate the association between the DII® and frailty, cognition, and the consequent risk of disability in older adults; (ii) to discuss particularities of the use of DII® with older adults.

METHODS

The research question was based on the PICOS strategy: Population = older adults; Intervention or Exposure = DII; Comparison = any comparator; Outcomes = frailty, cognition, and risk of disability; Type of study = cohort, cross-sectional or case-control studies. We searched publications in two electronic databases (PUBMED and Web of Science) up to May 20th, 2020.

RESULTS

Seven studies met our criteria. Three investigated cognition (one cohort and two cross-sectional), and four investigated frailty or risk of disability (one cohort and three cross-sectional); none of the studies investigated both outcomes (frailty and cognition) simultaneously. The studies presented some issues, mainly concerning: (i) the collection of dietary data and calculation of the DII; (ii) the study design; (iii) calculation of the sample size; (iv) eligibility criteria; (v) time for follow-up; (vi) and choice of covariates.

CONCLUSION

despite the issues, the use of DII resulted in a significant association, or predictive value, with variables related to frailty and cognitive decline. Further studies, with sensitivity analysis of the different components of this index, are needed. DII showed to be a promising tool in the investigation of geriatric syndromes. This systematic review was registered in PROSPERO (CRD42020155672).

The association between Dietary Inflammatory Index and disability in older adults

BACKGROUND & AIMS

The impact of the potential inflammatory effect of diet on disability has not been adequately investigated. We examined the association of Dietary Inflammatory Index (DII) on disability in older American adults and detected if these associations differed by stratification across sex and body mass index (BMI) level.

METHODS

Data were from the National Health and Nutrition Examination Survey (2007-2016). DII scores were calculated through two 24-h dietary recall interviews. Disability including functional limitations and activities of daily living (ADL) limitations were self-reported. The associations of DII scores on functional limitations and ADL limitations were evaluated by age-sex and multivariable adjusted logistic regression models and further stratification of these associations by sex and BMI level. Restricted cubic splines analyses were used to assess the shapes of these associations.

RESULTS

A total of 6893 participants aged 60 years and above were eligible for this study. DII was related to higher odds of functional limitations. Compared to the lowest quintile of DII scores, the odds ratio (OR) for participants in the second, third, fourth, and highest quintile were 1.61 (95%CI:1.20-2.15), 1.42(95%CI:1.09-1.85), 1.51 (95%CI:1.09-2.09) and 1.97 (95%CI:1.37-2.82) for functional limitations (P-trend = 0.003). The positive associations between DII scores and functional limitations were observed both in men and women. The corresponding ORs (95%CI) across all quintiles were 1.68(1.07-2.66), 1.54(1.06-2.25), 2.03(1.18-3.47), 2.11(1.19-3.74) in men (P-trend = 0.008) and 1.52(1.03-2.27), 1.32(0.86-2.02), 1.24(0.81-1.90), 1.74(1.11-2.73) in women (P-trend = 0.089). In the stratified analyses by BMI level, comparing the lowest quintiles, the corresponding ORs of functional limitations in second, third, fourth, and fifth quintiles were 2.71 (95% CI: 1.57-4.68), 2.39(95% CI: 1.38-4.11), 2.34(95% CI: 1.31-4.19), 2.54(95% CI: 1.25-5.13) in overweight (P-trend = 0.019) and 1.32(95% CI: 0.81-2.15), 1.17(95% CI: 0.71-1.92), 1.33(95% CI: 0.77-2.30), 2.15(95% CI: 1.19-3.87) in obesity (P-trend = 0.032).

CONCLUSIONS

The results provide evidence of a positive association between DII score and functional limitations in American older adults, especially participants with overweight and obesity.

Dietary Inflammatory Potential and the Risk of Neurodegenerative Diseases in Adults

Nutrition and diet have been suggested to enhance or inhibit cognitive performance and the risk of several neurodegenerative diseases. We conducted a systematic review to elucidate the relationship between the inflammatory capacity of a person's diet and the risk of incident neurodegenerative diseases. We searched major medical databases for articles published through June 30, 2018. Original, full-text, English-language articles on studies with human participants which investigated the link between dietary inflammatory potential and risk of developing neurodegenerative diseases were included. Duplicate and irrelevant studies were removed, and data were compiled through critical analysis. Initially, 457 articles were collected via the searching method, of which 196 studies remained after removal of duplicates. Fourteen articles were screened and found to be relevant to the scope of the review. After critical analysis, 10 were included in the final review. In all studies but one, a higher dietary inflammatory index (DII) was related to higher risk of developing neurodegenerative disease symptoms, including memory and cognition decline and multiple sclerosis. Of 3 studies that assessed the association of DII with levels of circulating inflammation markers, 2 indicated that DII was positively correlated with inflammatory marker levels. Low literacy, an unhealthy lifestyle, and individual nutritional status were the factors involved in a diet with inflammatory potential. These findings enhance confidence that DII is an appropriate tool for measurement of dietary inflammatory potential and validate the role of diets with inflammatory potential in the pathophysiology of neurodegenerative diseases. DII may be correlated with levels of circulating inflammatory markers.

Association between diet and migraine characteristics: The role of dietary inflammatory index

Background: Migraine is a neurologic disorder. Although, based on previous evidence, migraine is related with inflammation and oxidative stress, its relationship with the inflammatory potential of the diet is still unknown. Thus, the aim of this study was to show the correlation between Dietary Inflammatory Index (DII) and severity and duration of migraine headache. Methods: In this cross-sectional study, 266 women who suffered from migraine, were included. Demographic and anthropometric data were collected form all participants. 147-item semiquantitative food frequency questionnaire (FFQ) was collected to assess dietary intake and consequently, DII scores were calculated. Migraine Disability Assessment (MIDAS) questionnaire, Visual Analog Scale (VAS), and a 30-day headache diary were also completed by each participant. Results: The DII score ranged between -4.22 and 5.19 and its median [interquartile range (IQR)] was 0.003 (-1.48-1.55). There was no meaningful association between age, occupation, physical activity (PA), weight, height, Body Mass Index (BMI), waist circumference (WC), hip circumference, waist-to-hip ratio (WHR) and DII score classifications (P > 0.050). Subjects with more than 20 days of headache had higher DII score compared to those with less than 10 days per month [odds ratio (OR) = 1.60, 95% confidence interval (CI) = 1.12-2.08, P = 0.001]. There was no association between DII and migraine severity (VAS and MIDAS) in the crude and adjusted model of logistic regression. Although there was a significant association between headache duration and DII (P = 0.020), this relationship was not meaningful after adjusting for age, PA, BMI, and job status (OR = 0.53, 95% CI = 0.28-1.00, P = 0.052). Conclusion: The present study showed a direct association between headache frequency and DII. Nevertheless, any relationship was not found between headache duration or migraine severity and DII score. Future large and prospective studies are needed to explore the effect of inflammatory potential of diet in migraine characteristics.

Plant-Based Dietary Patterns, Plant Foods, and Age-Related Cognitive Decline

The aging population is expanding, as is the prevalence of age-related cognitive decline (ARCD). Of the several risk factors that predict the onset and progression of ARCD, 2 important modifiable risk factors are diet and physical activity. Dietary patterns that emphasize plant foods can exert neuroprotective effects. In this comprehensive review, we examine studies in humans of plant-based dietary patterns and polyphenol-rich plant foods and their role in either preventing ARCD and/or improving cognitive function. As yet, there is no direct evidence to support the benefits of a vegetarian diet in preventing cognitive decline. However, there is emerging evidence for brain-health-promoting effects of several plant foods rich in polyphenols, anti-inflammatory dietary patterns, and plant-based dietary patterns such as the Mediterranean diet that include a variety of fruits, vegetables, legumes, nuts, and whole grains. The bioactive compounds present in these dietary patterns include antioxidant vitamins, polyphenols, other phytochemicals, and unsaturated fatty acids. In animal models these nutrients and non-nutrients have been shown to enhance neurogenesis, synaptic plasticity, and neuronal survival by reducing oxidative stress and neuroinflammation. In this review, we summarize the mounting evidence in favor of plant-centered dietary patterns, inclusive of polyphenol-rich foods for cognitive well-being. Randomized clinical trials support the role of plant foods (citrus fruits, grapes, berries, cocoa, nuts, green tea, and coffee) in improving specific domains of cognition, most notably frontal executive function. We also identify knowledge gaps and recommend future studies to identify whether plant-exclusive diets have an added cognitive advantage compared with plant-centered diets with fish and/or small amounts of animal foods.

Dietary Inflammatory Index and Non-Communicable Disease Risk: A Narrative Review

There are over 1,000,000 publications on diet and health and over 480,000 references on inflammation in the National Library of Medicine database. In addition, there have now been over 30,000 peer-reviewed articles published on the relationship between diet, inflammation, and health outcomes. Based on this voluminous literature, it is now recognized that low-grade, chronic systemic inflammation is associated with most non-communicable diseases (NCDs), including diabetes, obesity, cardiovascular disease, cancers, respiratory and musculoskeletal disorders, as well as impaired neurodevelopment and adverse mental health outcomes. Dietary components modulate inflammatory status. In recent years, the Dietary Inflammatory Index (DII®), a literature-derived dietary index, was developed to characterize the inflammatory potential of habitual diet. Subsequently, a large and rapidly growing body of research investigating associations between dietary inflammatory potential, determined by the DII, and risk of a wide range of NCDs has emerged. In this narrative review, we examine the current state of the science regarding relationships between the DII and cancer, cardiometabolic, respiratory and musculoskeletal diseases, neurodevelopment, and adverse mental health outcomes. We synthesize the findings from recent studies, discuss potential underlying mechanisms, and look to the future regarding novel applications of the adult and children's DII (C-DII) scores and new avenues of investigation in this field of nutritional research.

Increased Dietary Inflammatory Index Is Associated with Schizophrenia: Results of a Case-Control Study from Bahrain

BACKGROUND

Several studies have indicated that chronic low-grade inflammation is associated with the development of schizophrenia. Given the role of diet in modulating inflammatory markers, excessive caloric intake and increased consumption of pro-inflammatory components such as calorie-dense, nutrient-sparse foods may contribute toward increased rates of schizophrenia. This study aimed to examine the association between dietary inflammation, as measured by the dietary inflammatory index (DII^®), and schizophrenia.

METHODS

A total of 120 cases attending the out-patient department in the Psychiatric Hospital/Bahrain were recruited, along with 120 healthy controls matched on age and sex. The energy-adjusted DII (E-DII) was computed based on dietary intake assessed using a comprehensive food frequency questionnaire (FFQ). Logistic regression was used to estimate odds ratios and 95% confidence intervals, adjusting for potential confounders including age, sex, body mass index, education, employment, diabetes, hypertension, and cardiovascular disease with E-DII expressed both as a continuous variable and categorized as quartiles.

RESULTS

The mean E-DII score for the entire sample was 1.79 ± 1.52, indicating a generally pro-inflammatory diet. The cases with schizophrenia appeared to have a higher E-DII score compared to controls: 1.99 ± 1.39 vs. 1.60 ± 1.38, respectively (p = 0.009). For every one unit increase in the E-DII score, the odds of having schizophrenia increased by 62% (OR 1.62; 95% CI 1.17-2.26). Similarly, increased risk was observed when the E-DII was used as quartiles, with participants in most pro-inflammatory quartile 4 being nearly 6 times more likely to be schizophrenic than participants in the most anti-inflammatory group quartile 1 (OR 5.96; 1.74-20.38; p-trend = 0.01).

CONCLUSIONS

The data suggest that a pro-inflammatory diet, as indicated by increasing E-DII score, is associated with schizophrenia. This is the first study to examine the association between the DII and schizophrenia in a Middle Eastern population. Although these results are consistent with findings from research conducted in depression, additional studies are required before generalizing the findings to other populations.

Dietary Inflammatory Index and Sleep Quality in Southern Italian Adults

BACKGROUND

Current evidence supports the central role of a subclinical, low-grade inflammation in a number of chronic illnesses and mental disorders; however, studies on sleep quality are scarce. The aim of this study was to test the association between the inflammatory potential of the diet and sleep quality in a cohort of Italian adults.

METHODS

A cross-sectional analysis of baseline data of the Mediterranean healthy Eating, Aging, and Lifestyle (MEAL) study was conducted on 1936 individuals recruited in the urban area of Catania during 2014-2015 through random sampling. A food frequency questionnaire and other validated instruments were used to calculate the dietary inflammatory index (DII®) and assess sleep quality (Pittsburg sleep quality index). Multivariable logistic regression analyses were performed to determine the association between exposure and outcome.

RESULTS

Individuals in the highest quartile of the DII were less likely to have adequate sleep quality (odds ratio (OR) = 0.49, 95% CI: 0.31, 0.78). Among individual domains of sleep quality, an association with the highest exposure category was found only for sleep latency (OR = 0.60, 95% CI: 0.39, 0.93).

CONCLUSIONS

The inflammatory potential of the diet appears to be associated with sleep quality in adults. Interventions to improve diet quality might consider including a dietary component that aims to lower chronic systemic inflammation to prevent cognitive decline and improve sleep quality.

Diet and Inflammation in Cognitive Ageing and Alzheimer's Disease

PURPOSE OF REVIEW

Nutrition is known to modulate the immune system and may alter neuroinflammatory processes implicated in the pathogenesis of Alzheimer's disease (AD) and progression of neurodegeneration. Here, we review the evidence for healthy dietary patterns and age-related cognition and discuss potential neuroinflammatory actions of diet on cognitive function.

RECENT FINDINGS

Anti-inflammatory dietary patterns such as the Mediterranean diet (MD) and dietary approaches to stop hypertension (DASH) may be neuroprotective. Several dietary components consumed in the MD and DASH (omega-3 fatty acids, antioxidants and polyphenols) can inhibit neuroinflammation associated with AD. Anti-inflammatory diets may also attenuate neuroinflammation via indirect immune pathways from the gut microbiome and systemic circulation. Diet may influence cognitive ageing via several inflammatory pathways. However, data from human studies are lacking and the exact mechanisms linking diet to cognitive function remain elusive. Further dietary intervention studies are required to investigate diet-associated neurological change from the earliest through to latest stages of cognitive decline. Furthermore, incorporation of neuroimaging measures in intervention studies would advance current understanding of the mechanistic effects of dietary modification on neuroinflammation in the ageing brain.

Perspective: The Dietary Inflammatory Index (DII)-Lessons Learned, Improvements Made, and Future Directions

The literature on the role of inflammation in health has grown exponentially over the past several decades. Paralleling this growth has been an equally intense focus on the role of diet in modulating inflammation, with a doubling in the size of the literature approximately every 4 y. The Dietary Inflammatory Index (DII) was developed to provide a quantitative means for assessing the role of diet in relation to health outcomes ranging from blood concentrations of inflammatory cytokines to chronic diseases. Based on literature from a variety of different study designs ranging from cell culture to observational and experimental studies in humans, the DII was designed to be universally applicable across all human studies with adequate dietary assessment. Over the past 4 y, the DII has been used in >200 studies and forms the basis for 12 meta-analyses. In the process of conducting this work, lessons were learned with regard to methodologic issues related to total energy and nutrient intake and energy and nutrient densities. Accordingly, refinements to the original algorithm have been made. In this article we discuss these improvements and observations that we made with regard to misuse and misinterpretation of the DII and provide suggestions for future developments.

Dietary inflammatory index is positively associated with serum high-sensitivity C-reactive protein in a Korean adult population

OBJECTIVE

To our knowledge, only a few studies have explored the relationship between the inflammatory potential of diet and serum inflammatory markers in Korean adults. The likely novel aim of this study was to examine the association between the dietary inflammatory index (DII) and serum high-sensitivity C-reactive protein (hs-CRP) in a Korean adult population.

METHODS

A cross-sectional study was conducted using the data set from the Korea National Health and Nutrition Examination Survey (KNHANES) 2015. Korean adults ≥19 y of age with hs-CRP values were included in this study. After excluding individuals with missing variables for covariates, the final analytic sample for the study was 3014 adults (1295 men and 1719 women). DII scores were calculated from a 1-d 24-h dietary recall, and hs-CRP was measured using the immunoturbidimetric method. Multivariable logistic regression analyses were performed to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) to test the effect of the DII score on serum hs-CRP as dichotomous (>2 versus ≤2 mg/L).

RESULTS

A significant association was observed between increasing DII scores and elevated hs-CRP. Korean adults in the highest quintile of the DII (indicating the most proinflammatory diet), compared with the lowest quintile of the DII (indicating the most anti-inflammatory diet), had increased odds of having elevated hs-CRP concentrations (>2 mg/L; AOR, 1.70; 95% CI, 1.07-2.69; P_trend < 0.0001) after controlling for age, sex, education, marital status, alcohol consumption, smoking status, body mass index, high-density lipoprotein cholesterol, and physical activity.

CONCLUSION

Higher DII scores were positively associated with elevated hs-CRP levels in Korean adults. Because inflammation affects the risk for cancer, cardiovascular disease, and other inflammation-related conditions, future studies are warranted to examine the effect of the DII on other inflammatory biomarkers and chronic disease outcomes among the Korean population.

A Pro-Inflammatory Diet Is Associated With an Increased Odds of Depression Symptoms Among Iranian Female Adolescents: A Cross-Sectional Study

Background: The relation between dietary inflammation and risk of depression has not been widely explored. We examined the association between the inflammatory effect of the diet and the odds of depression among Iranian female adolescents. Methods: Using a stratified cluster sampling technique, 300 female adolescents aged 15-18 years were recruited from schools in Tehran between years 2014-2015. Depression was assessed using the Depression, Anxiety and Stress Scale (DASS)- a 21-point scale. The dietary inflammatory index (DII®) was used to evaluate the inflammatory potential of the diet. Dietary intake was assessed using a validated food frequency questionnaire. In addition to descriptive statistics, multivariable linear and logistic regression were used to calculate confounder-adjusted beta estimates and odds ratios. Results: In total, 88 females (30%) had at least a moderate level of depressive symptoms (DASS > 6). Females with the most pro-inflammatory diet had higher DASS depression score (β = 1.67; 95% CI = 0.03, 3.31) and were at 3.96 (95% CI = 1.12, 13.97) times higher odds of having at least moderate depressive symptoms, compared to females with the least anti-inflammatory diets. Conclusion: These data suggest that Iranian adolescent females eating a pro-inflammatory diet, as indicated by higher DII scores, had greater odds of having at least moderate depressive symptoms.