The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD): rationale, study design, and cohort description

Mediterranean diet and cognitive health: Initial results from the Hellenic Longitudinal Investigation of Ageing and Diet

Background

The Mediterranean dietary pattern has been associated with a decreased risk of many degenerative diseases and cognitive function in particular; however, relevant information from Mediterranean regions, where the prototype Mediterranean diet is typically adhered to, have been very limited. Additionally, predefined Mediterranean diet (MeDi) scores with use of a priori cut-offs have been used very rarely, limiting comparisons between different populations and thus external validity of the associations. Finally, associations between individual components of MeDi (i.e., food groups, macronutrients) and particular aspects of cognitive performance have rarely been explored. We evaluated the association of adherence to an a priori defined Mediterranean dietary pattern and its components with dementia and specific aspects of cognitive function in a representative population cohort in Greece.

Methods

Participants from the Hellenic Longitudinal Investigation of Ageing and Diet (HELIAD), an on-going population-based study, exploring potential associations between diet and cognitive performance in a representative sample from Greek regions, were included in this analysis. Diagnosis of dementia was made by a full clinical and neuropsychological evaluation, while cognitive performance was assessed according to five cognitive domains (memory, language, attention-speed, executive functioning, visuospatial perception) and a composite cognitive score. Adherence to MeDi was evaluated by an a priori score (range 0–55), derived from a detailed food frequency questionnaire.

Results

Among 1,865 individuals (mean age 73±6 years, 41% male), 90 were diagnosed with dementia and 223 with mild cognitive impairment. Each unit increase in the Mediterranean dietary score (MedDietScore) was associated with a 10% decrease in the odds for dementia. Adherence to the MeDi was also associated with better performance in memory, language, visuospatial perception and the composite cognitive score; the associations were strongest for memory. Fish consumption was negatively associated with dementia and cognitive performance positively associated with non-refined cereal consumption.

Conclusions

Our results suggest that adherence to the MeDi is associated with better cognitive performance and lower dementia rates in Greek elders. Thus, the MeDi in its a priori constructed prototype form may have cognitive benefits in traditional Mediterranean populations.

Sleep quality and duration in relation to memory in the elderly: Initial results from the Hellenic Longitudinal Investigation of Aging and Diet

BACKGROUND

Sleep is crucial for cognition, particularly for memory, given its complex association with neurodegenerative processes. The aim of the present study was to examine the association between sleep quality as well as sleep duration and memory performance in a Greek elderly population.

SETTING

Cross-sectional design in the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population representative study of Greek elderly (65years or older).

METHODS

Data from 1589 participants free of sleep medication were included. Sleep quality was estimated by using the Sleep Scale from the Medical Outcomes Study. An extensive neuropsychological assessment examining memory was administered to each participant. Linear regression analyses were used to examine whether sleep quality (higher score, poor quality) and/or sleep duration were associated with memory expressed in the form of a z-score. Age, sex, education, and body mass index were included as covariates. The main analyses were conducted first on the total sample, then with the exclusion of demented participants, and finally with the exclusion of both demented and participants with Mild Cognitive Impairment (MCI). We then conducted further analyses on the non-demented, non-MCI group, initially stratified by Apolipoprotein E-ε4 gene. We further examined the role of co-morbidities, as well as the association between sleep duration groups and memory. We also explored any interaction effect between sex and sleep quality/duration on memory. We then examined the associations between components of sleep measures and memory scores. Lastly, we examined the associations between sleep quality/duration and verbal/non-verbal memory separately.

RESULTS

In the total sample, we noted significant associations between sleep duration and memory (B=-0.001, p≤0.0001), but not for sleep quality and memory (B=-0.038, p=0.121). After excluding the demented participants, the associations were significant for: sleep quality and memory (B=-0.054, p=0.023), and sleep duration and memory (B=-0.001, p≤0.0001). After excluding both the MCI and the demented subjects, the associations between sleep quality and memory (B=-0.065, p=0.006), and sleep duration and memory (B=-0.001, p=0.003) were still significant. The association between the sleep duration groups and memory function was also significant, such that poor memory performance was associated with the longer sleep duration group. The results remained significant even after controlling for the co-morbidities, as well as after adding in the model anxiety and depression as covariates. Associations between sleep quality and memory, and sleep duration and memory were present in the ApoE-ε4 non-carriers. The individual sleep questions that were probably shown to be driving the associations between sleep and memory were: time to fall asleep, sleep not quiet, getting enough sleep to feel rested upon waking in the morning, and getting the amount of sleep needed. Sleep duration was associated with both verbal and non-verbal memory, while sleep quality was only associated with verbal memory.

CONCLUSION

Poor sleep quality and longer sleep duration were linked to low memory performance, independent of demographic and clinical factors, in a large sample of cognitively healthy older Greek adults. Other parameters than sleep and memory measurements could play an important role on the association. Levels of melatonin, or circadian rhythms dysregulation might play a crucial role in the above associations.

Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study

BACKGROUND

The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline.

METHODS AND FINDINGS

We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54-105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2-16 assessment waves (median = 3) and a follow-up duration of 2-15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p < 0.001) for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002). There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021) on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001) than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009). Males declined on the MMSE at a slightly slower rate than females (difference = 0.023 SD/decade, 95% CI [0.011, 0.035], p < 0.001), and every additional year of education was associated with a rate of decline slightly slower for the MMSE (0.004 SD/decade less, 95% CI [0.002, 0.006], p = 0.001), but slightly faster for language (-0.007 SD/decade more, 95% CI [-0.011, -0.003], p = 0.001). APOE*4 carriers declined slightly more rapidly than non-carriers on most cognitive measures, with processing speed showing the greatest difference (-0.08 SD/decade, 95% CI [-0.15, -0.01], p = 0.019). The same overall pattern of results was found when analyses were repeated with baseline dementia cases excluded. We used only one test to represent cognitive domains, and though a prototypical one, we nevertheless urge caution in generalizing the results to domains rather than viewing them as test-specific associations. This study lacked cohorts from Africa, India, and mainland China.

CONCLUSIONS

Cognitive performance declined with age, and more rapidly with increasing age, across samples from diverse ethnocultural groups and geographical regions. Associations varied across cohorts, suggesting that different rates of cognitive decline might contribute to the global variation in dementia prevalence. However, the many similarities and consistent associations with education and APOE genotype indicate a need to explore how international differences in associations with other risk factors such as genetics, cardiovascular health, and lifestyle are involved. Future studies should attempt to use multiple tests for each cognitive domain and feature populations from ethnocultural groups and geographical regions for which we lacked data.

Observational study assessing demographic, economic and clinical factors associated with access and utilization of health care services of patients with multiple sclerosis under treatment with interferon beta-1b (EXTAVIA)

Multiple sclerosis (MS) results in an extensive use of the health care system, even within the first years of diagnosis. The effectiveness and accessibility of the health care system may affect patients' quality of life. The aim of the present study was to evaluate the health care resource use of MS patients under interferon beta-1b (EXTAVIA) treatment in Greece, the demographic or clinical factors that may affect this use and also patient satisfaction with the health care system. Structured interviews were conducted for data collection. In total, 204 patients (74.02% females, mean age (SD) 43.58 (11.42) years) were enrolled in the study. Analysis of the reported data revealed that during the previous year patients made extensive use of health services in particular neurologists (71.08% visited neurologists in public hospitals, 66.67% in private offices and 48.53% in insurance institutes) and physiotherapists. However, the majority of the patients (52.45%) chose as their treating doctor private practice neurologists, which may reflect accessibility barriers or low quality health services in the public health system. Patients seemed to be generally satisfied with the received health care, support and information on MS (84.81% were satisfied from the information provided to them). Patients' health status (as denoted by disease duration, disability status and hospitalization needs) and insurance institute were found to influence their visits to neurologists. Good adherence (up to 70.1%) to the study medication was reported. Patients' feedback on currently provided health services could direct these services towards the patients' expectations.