Glycemic Dysregulations Are Associated With Worsening Cognitive Function in Older Participants at High Risk of Cardiovascular Disease: Two-Year Follow-up in the PREDIMED-Plus Study

The association of glucose metabolism measures and diabetes status with Alzheimer's disease biomarkers of amyloid and tau: A systematic review and meta-analysis

Conflicting evidence exists on the relationship between diabetes mellitus (DM) and Alzheimer's disease (AD) biomarkers. Therefore, we conducted a random-effects meta-analysis to evaluate the correlation of glucose metabolism measures (glycated hemoglobin, fasting blood glucose, insulin resistance indices) and DM status with AD biomarkers of amyloid-β and tau measured by positron emission tomography or cerebrospinal fluid. We selected 37 studies from PubMed and Embase, including 11,694 individuals. More impaired glucose metabolism and DM status were associated with higher tau biomarkers (r=0.11[0.03-0.18], p=0.008; I2=68%), but were not associated with amyloid-β biomarkers (r=-0.06[-0.13-0.01], p=0.08; I2=81%). Meta-regression revealed that glucose metabolism and DM were specifically associated with tau biomarkers in population settings (p=0.001). Furthermore, more impaired glucose metabolism and DM status were associated with lower amyloid-β biomarkers in memory clinic settings (p=0.004), and in studies with a higher prevalence of dementia (p<0.001) or lower cognitive scores (p=0.04). These findings indicate that DM is associated with biomarkers of tau but not with amyloid-β. This knowledge is valuable for improving dementia and DM diagnostics and treatment.

Microbial Phenolic Metabolites Are Associated with Improved Cognitive Health

SCOPE

Diets rich in polyphenols has been associated with better cognitive performance. The aim of this study is to assess the relationship between microbial phenolic metabolites (MPM) in urine and cognition in the context of an older population at high cardiovascular risk.

METHODS AND RESULTS

A cross-sectional analysis is conducted in 400 individuals of the PREDIMED-Plus study. Liquid chromatography coupled to mass spectrometry is used to identify urinary MPM. Mediterranean diet (MedDiet) adherence is estimated with a 17-item questionnaire and cognitive function is evaluated with a battery of neuropsychological tests. Multivariable-adjusted linear regression models are fitted to assess the relationship of urinary MPM with the MedDiet and cognitive tests. Protocatechuic acid and enterolactone glucuronide are associated with higher adherence to the MedDiet. Regarding cognitive function, protocatechuic acid, vanillic acid glucuronide, 3-hydroxybenzoic acid, enterodiol glucuronide, and enterolactone glucuronide are directly associated with a global composite score of all the cognitive tests. Furthermore, protocatechuic acid and enterolactone glucuronide are associated with higher scores in the Mini-Mental State Examination, whereas enterodiol glucuronide is associated with improved Clock Drawing Test scores.

CONCLUSIONS

These results suggest that the MedDiet is linked to MPM associated with better cognitive performance in an older population.

Assessment of circulating insulin using liquid chromatography-mass spectrometry during insulin glargine treatment in type 2 diabetes: Implications for estimating insulin sensitivity and β-cell function

AIM

To determine the potential impact of the cross-reactivity of insulin glargine U-100 and its metabolites on insulin sensitivity and β-cell measures in people with type 2 diabetes.

MATERIALS AND METHODS

Using liquid chromatography-mass spectrometry (LC-MS), we measured concentrations of endogenous insulin, glargine and its two metabolites (M1 and M2) in fasting and oral glucose tolerance test-stimulated plasma from 19 participants and fasting specimens from another 97 participants 12 months after randomization to receive the insulin glargine. The last dose of glargine was administered before 10:00 PM the night before testing. Insulin was also measured on these specimens using an immunoassay. We used fasting specimens to calculate insulin sensitivity (Homeostatic Model Assessment 2 [HOMA2]-S%; QUICKI index; PREDIM index) and β-cell function (HOMA2-B%). Using specimens following glucose ingestion, we calculated insulin sensitivity (Matsuda ISI[comp] index) and β-cell response (insulinogenic index [IGI], and total incremental insulin response [iAUC] insulin/glucose).

RESULTS

In plasma, glargine was metabolized to form the M1 and M2 metabolites that were quantifiable by LC-MS; however, the analogue and its metabolites cross-reacted by less than 100% in the insulin immunoassay. This incomplete cross-reactivity resulted in a systematic bias of fasting-based measures. By contrast, because M1 and M2 did not change following glucose ingestion, a bias was not observed for IGI and iAUC insulin/glucose.

CONCLUSIONS

Despite glargine metabolites being detected in the insulin immunoassay, dynamic insulin responses can be used to assess β-cell responsiveness. However, given the cross-reactivity of the glargine metabolites in the insulin immunoassay, fasting-based measures of insulin sensitivity and β-cell function are biased.

The Triglyceride-Glucose Index Is Associated with Longitudinal Cognitive Decline in a Middle-Aged to Elderly Population: A Cohort Study

BACKGROUND

To examine the effect of the triglyceride-glucose (TyG) index on longitudinal cognitive decline in a healthy middle-aged-to-elderly population.

METHODS

We conducted a population-based longitudinal study. A total of 1774 participants without cognitive impairment were enrolled in the 4-year follow-up. They were divided into four groups according to the quartile of the TyG index. Multivariable-adjusted Cox proportional hazard models were performed to examine the association between the TyG index and cognitive decline. Discrimination tests were used to evaluate the incremental predictive value of the TyG index beyond conventional risk factors.

RESULTS

During the follow-up, compared with those in the bottom quartile group, participants in the top TyG quartile group presented a 51% increase in the risk of cognitive decline (OR 1.51 (95% CI: 1.06-2.14)). As shown by discrimination tests, adding the TyG index into the conventional model resulted in a slight improvement in predicting the risk of cognitive decline (NRI 16.00% (p = 0.004)).

CONCLUSION

This study demonstrated that increasing values of the TyG index were positively associated with the risk of cognitive decline. Monitoring the TyG index may help in the early identification of individuals at high risk of cognitive deterioration.

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.

Mediterranean, DASH, and MIND Dietary Patterns and Cognitive Function: The 2-Year Longitudinal Changes in an Older Spanish Cohort

Background and Aims: Plant-forward dietary patterns have been associated with cardiometabolic health benefits, which, in turn, have been related to cognitive performance with inconsistent findings. The objective of this study was to examine the relationship between baseline adherence to three a priori dietary patterns (Mediterranean, DASH, and MIND diets) with 2-year changes in cognitive performance in older adults with overweight or obesity and high cardiovascular disease risk. Methods: A prospective cohort analysis was conducted within the PREDIMED-Plus trial, involving 6,647 men and women aged 55-75 years with overweight or obesity and metabolic syndrome. Using a validated, semiquantitative 143-item food frequency questionnaire completed at baseline, the dietary pattern adherence scores were calculated. An extensive neuropsychological test battery was administered at baseline and 2-year follow-up. Multivariable-adjusted linear regression models were used to assess associations between 2-year changes in cognitive function z-scores across tertiles of baseline adherence to the a priori dietary patterns. Results: Adherence to the Mediterranean diet at baseline was associated with 2-year changes in the general cognitive screening Mini-Mental State Examination (MMSE, β: 0.070; 95% CI: 0.014, 0.175, P-trend = 0.011), and two executive function-related assessments: the Trail Making Tests Part A (TMT-A, β: -0.054; 95% CI: -0.110, - 0.002, P-trend = 0.047) and Part B (TMT-B, β: -0.079; 95% CI: -0.134, -0.024, P-trend = 0.004). Adherence to the MIND diet was associated with the backward recall Digit Span Test assessment of working memory (DST-B, β: 0.058; 95% CI: 0.002, 0.114, P-trend = 0.045). However, higher adherence to the DASH dietary pattern was not associated with better cognitive function over a period of 2 years. Conclusion: In older Spanish individuals with overweight or obesity and at high cardiovascular disease risk, higher baseline adherence to the Mediterranean dietary pattern may be associated with better cognitive performance than lower adherence over a period of 2 years.

Mediterranean, DASH, and MIND Dietary Patterns and Cognitive Function: The 2-Year Longitudinal Changes in an Older Spanish Cohort

Background and Aims: Plant-forward dietary patterns have been associated with cardiometabolic health benefits, which, in turn, have been related to cognitive performance with inconsistent findings. The objective of this study was to examine the relationship between baseline adherence to three a priori dietary patterns (Mediterranean, DASH, and MIND diets) with 2-year changes in cognitive performance in older adults with overweight or obesity and high cardiovascular disease risk. Methods: A prospective cohort analysis was conducted within the PREDIMED-Plus trial, involving 6,647 men and women aged 55-75 years with overweight or obesity and metabolic syndrome. Using a validated, semiquantitative 143-item food frequency questionnaire completed at baseline, the dietary pattern adherence scores were calculated. An extensive neuropsychological test battery was administered at baseline and 2-year follow-up. Multivariable-adjusted linear regression models were used to assess associations between 2-year changes in cognitive function z-scores across tertiles of baseline adherence to the a priori dietary patterns. Results: Adherence to the Mediterranean diet at baseline was associated with 2-year changes in the general cognitive screening Mini-Mental State Examination (MMSE, β: 0.070; 95% CI: 0.014, 0.175, P-trend = 0.011), and two executive function-related assessments: the Trail Making Tests Part A (TMT-A, β: -0.054; 95% CI: -0.110, - 0.002, P-trend = 0.047) and Part B (TMT-B, β: -0.079; 95% CI: -0.134, -0.024, P-trend = 0.004). Adherence to the MIND diet was associated with the backward recall Digit Span Test assessment of working memory (DST-B, β: 0.058; 95% CI: 0.002, 0.114, P-trend = 0.045). However, higher adherence to the DASH dietary pattern was not associated with better cognitive function over a period of 2 years. Conclusion: In older Spanish individuals with overweight or obesity and at high cardiovascular disease risk, higher baseline adherence to the Mediterranean dietary pattern may be associated with better cognitive performance than lower adherence over a period of 2 years.