Association between subclinical thyroid dysfunction and cognitive decline: findings from the ELSA-Brasil study.

BACKGROUND: Thyroid dysfunction has been associated with cognitive decline and dementia. However, the role of subtle thyroid hormone alterations in cognitive function is still debatable. METHODS: Participants without overt thyroid dysfunction aged 35-74 years at baseline were evaluated in three study waves (2008-10, 2012-14, and 2017-19). We assessed baseline thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Cognitive performance was evaluated every four years in each wave using 10-word immediate and late recall, word recognition, semantic (animals category) and phonemic (letter f) verbal fluency, and the trail-making B-version tests. A global composite z-score was derived from these tests. The associations of TSH, FT4, and FT3 levels with cognitive decline over time were evaluated using linear mixed-effect models adjusted for sociodemographic, clinical, and lifestyle variables. RESULTS: In 9,524 participants (mean age 51.2±8.9 years old, 51% women, 52% White), there was no association between baseline TSH, FT4, and FT3 levels and cognitive decline during the follow-up. However, increase in FT4 levels over time was associated with faster memory (ß=-0.004, 95%CI=-0.007; -0.001, p=0.014), verbal fluency (ß=-0.003, 95%CI=-0.007; -0.0005, p=0.021), executive function (ß=-0.004, 95%CI=-0.011; -0.003, p<0.001), and global cognition decline (ß=-0.003, 95%CI=-0.006; -0.001, p=0.001). Decrease in FT4 levels over time was associated with faster verbal fluency (ß=-0.003, 95%CI=-0.007; -0.0004, p=0.025) and executive function (ß=-0.004, 95%CI=-0.007; -0.0003, p=0.031) decline. CONCLUSION: An increase or decrease in FT4 levels over time was associated with faster cognitive decline in middle-aged and older adults without overt thyroid dysfunction during 8 years of follow-up.

Adherence to the planetary health diet and cognitive decline: findings from the ELSA-Brasil study.

The EAT-Lancet Commission proposed a planetary health diet to improve human health within planetary boundaries; however, little is known about the association between adherence to this diet and cognitive decline. We used data from three waves of the Brazilian Longitudinal Study of Adult Health to evaluate the association between the planetary health diet and cognitive decline using linear mixed-effects models. Here we show that in 11,737 participants (mean (s.d.) age 51.6 (9.0) years, 54% women and 53% white), higher adherence to the planetary health diet was associated with slower memory decline (P = 0.046) and that income was a modifier in this association (P < 0.001). Adherence to the planetary health diet was associated with slower decline of memory (P = 0.040) and global cognition (P = 0.009) in high-income participants. No association was found among low-income participants. The results of our study highlight that the promotion of healthy dietary patterns should take into consideration income barriers as well as differences in dietary habits to achieve high adherence.

Dietary folate intake and its association with longitudinal changes in cognition function.

BACKGROUND & AIMS: Folate (vitamin B9) is an essential co-factor for one-carbon metabolism. Controversial evidence has emerged regarding the association between folate and cognitive performance. The aim of the study was to investigate the association between baseline dietary folate intake and cognitive decline in a population exposed to mandatory fortification during a median follow-up of 8 years. METHODS: Multicenter, prospective cohort study involving 15,105 public servants aged 35-74 years old, both sexes, from The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Baseline dietary intake was assessed by a Food Frequency Questionnaire (FFQ). Six cognitive tests were performed in the three waves to assess memory, executive function and global cognition. Linear mixed-effects models were used to assess the association between dietary folate intake at baseline and changes in cognition over time. RESULTS: Data from 11,276 participants were analyzed. The mean (SD) age was 51.7 (9) years, 50% were women, 63% were overweight/obese, and 56% had graduated from college or more. Overall dietary folate intake was not associated with cognitive decline; neither vitamin B12 intake was a modifier of this association. General dietary supplements and specifically multivitamins use did not affect these findings. Natural food folate group was associated with a slower rate of global cognitive decline (ß (95% CI): 0.001 (0.000; 0.002), P = 0.015). There was no association between fortified food group and cognition scores. CONCLUSION: Overall dietary folate intake was not associated with cognitive function in this Brazilian population. However, folate naturally occurring in food sources may slow global cognitive decline.

Prevalence of Dementia and Cognitive Impairment No Dementia in a Large and Diverse Nationally Representative Sample: The ELSI-Brazil Study.

BACKGROUND: Approximately 77% of older adults with dementia in Brazil have not been diagnosed, indicating a major public health issue. Previous epidemiological dementia studies in Brazil were based on data from 1 geopolitical region. METHODS: We aimed to estimate the general and subgroup-specific (age, education, and sex) prevalence of dementia and cognitive impairment no dementia (CIND) classification using data from 5 249 participants aged 60 years and older from the ELSI-Brazil, a large nationally representative sample. Participants were classified as having normal cognitive function, CIND, or dementia based on a combination of the individual's cognitive and functional status. RESULTS: We found a general prevalence of 5.8% (95% CI = 4.7-7.2) for dementia and 8.1% (95% CI = 6.8-9.5) for CIND. Dementia prevalence ranged from 3.2% (60-64 years old) to 42.8% (≥90 years old) by age, and from 2.1% (college level or higher) to 16.5% (illiterates) by education. Females had a higher dementia prevalence (6.8%) than males (4.6%). CIND prevalence was similar across age, sex, and education. CONCLUSIONS: The estimated dementia prevalence is lower than that in previous Brazilian epidemiological studies, but is in line with other Latin American studies. Only 1.2% of the ELSI-Brazil participants reported having a previous diagnosis of dementia, revealing that underdiagnosis is rampant and a common reality. Based on our results and national statistics projections, we estimate that in 2019, there were 1 757 480 people aged 60 years and older living with dementia in Brazil and, at least, another 2 271 314 having to deal with some form of cognitive impairment.

Different Sources of Sugar Consumption and Cognitive Performance in Older Adults: Data From the National Health and Nutrition Examination Survey 2011-2014.

OBJECTIVES: Excess sugar consumption, particularly in sugar-sweetened beverages (SSBs), has been linked to poor cognitive performance. We aimed to assess the association of consumption of total sugar, as well as the consumption of SSBs, solid desserts, and 100% fruit juice with cognitive performance among older adults. METHODS: Consumption of total sugar, SSBs, solid desserts, and 100% fruit juice were obtained from the 24-hr recall interview. Cognitive performance was evaluated using the Consortium to Establish a Registry for Alzheimer's Disease word list, the Animal Fluency Test, and the Digit Symbol Substitution Test. Binary logistic regression models were used to evaluate the association between consumption of sugar (total and from different sources) and cognitive performance. RESULTS: A total of 1,938 participants aged 60 years or older from the National Health and Nutrition Examination Survey 2011-2014 were included. Compared to the lowest tertile, the highest tertile of total sugar consumption was independently associated with higher odds of low memory performance (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 1.00; 3.50, p = .049). Consumption of SSBs was associated with higher risk of low memory (OR = 1.58, 95% CI = 1.11; 2.25, p = .014), whereas consumption of solid desserts was associated with lower risk of low verbal fluency performance (OR = 0.62, 95% CI = 0.41; 0.95, p = .032). DISCUSSION: Higher consumption of total sugars and SSBs was associated with lower memory performance, while consumption of solid desserts was associated with higher verbal fluency performance.

Association Between Consumption of Ultraprocessed Foods and Cognitive Decline.

Importance: Although consumption of ultraprocessed food has been linked to higher risk of cardiovascular disease, metabolic syndrome, and obesity, little is known about the association of consumption of ultraprocessed foods with cognitive decline. Objective: To investigate the association between ultraprocessed food consumption and cognitive decline in the Brazilian Longitudinal Study of Adult Health. Design, Setting, and Participants: This was a multicenter, prospective cohort study with 3 waves, approximately 4 years apart, from 2008 to 2017. Data were analyzed from December 2021 to May 2022. Participants were public servants aged 35 to 74 years old recruited in 6 Brazilian cities. Participants who, at baseline, had incomplete food frequency questionnaire, cognitive, or covariate data were excluded. Participants who reported extreme calorie intake (<600 kcal/day or >6000 kcal/day) and those taking medication that could negatively interfere with cognitive performance were also excluded. Exposures: Daily ultraprocessed food consumption as a percentage of total energy divided into quartiles. Main Outcomes and Measures: Changes in cognitive performance over time evaluated by the immediate and delayed word recall, word recognition, phonemic and semantic verbal fluency tests, and Trail-Making Test B version. Results: A total of 15 105 individuals were recruited and 4330 were excluded, leaving 10 775 participants whose data were analyzed. The mean (SD) age at the baseline was 51.6 (8.9) years, 5880 participants (54.6%) were women, 5723 (53.1%) were White, and 6106 (56.6%) had at least a college degree. During a median (range) follow-up of 8 (6-10) years, individuals with ultraprocessed food consumption above the first quartile showed a 28% faster rate of global cognitive decline (ß = -0.004; 95% CI, -0.006 to -0.001; P = .003) and a 25% faster rate of executive function decline (ß = -0.003, 95% CI, -0.005 to 0.000; P = .01) compared with those in the first quartile. Conclusions and Relevance: A higher percentage of daily energy consumption of ultraprocessed foods was associated with cognitive decline among adults from an ethnically diverse sample. These findings support current public health recommendations on limiting ultraprocessed food consumption because of their potential harm to cognitive function.