Social network and the risk for developing mild cognitive impairment and dementia among older adults.

BACKGROUND: This study aimed to investigate the longitudinal associations between social network (SN) and the risk of lower cognitive function, mild cognitive impairment (MCI), and dementia among cognitively normal individuals 65 years and older. METHODS: Data from the Age, Gene/Environment Susceptibility (AGES) Reykjavik Study on 2816 participants (aged 65 to 96 years) were used to examine the associations using multiple logistic and linear regression models. SN included questions on frequency of contact with family and friends as well as information on marital status, resulting in a score ranging from 0 (poor social network) to 3 (good social network). Cognitive function outcomes included the speed of processing (SP), executive function (EF) and memory function (MF). MCI and dementia were diagnosed using a detailed assessment according to international guidelines. RESULTS: At baseline 0.5, 7.0, 41.7 and 50.8% reported a score of 0, 1, 2 and 3, respectively. During a mean follow-up time of 5.2 years, 7.1% (n = 188) of cognitively intact participants developed MCI and 3.0% (n = 79) developed dementia. Longitudinal analyses demonstrated that participants who had low SN were significantly more likely to have declines in MF (ß = - 0.533, P = 0.014) compared to high SN. Social networks were not independently associated with the decline of SP and EF during follow-up. According to fully adjusted models using logistic regression, SN was significantly associated with incidence risk of MCI (OR = 2.030, P = 0.014 and OR = 1.847 P = 0.001). These associations were largely independent of other lifestyle factors, depression and genetic disposition. CONCLUSIONS: Community-dwelling older adults who have poor social networks have a higher risk of declining memory function as well as a higher risk of mild cognitive impairment than older adults who have a higher social network. This study included numbers of relevant covariates in the study analysis, thereby significantly contributing to the literature on cognitive aging.

Serum 25-Hydroxy-Vitamin D Status and Incident Hip Fractures in Elderly Adults: Looking Beyond Bone Mineral Density.

Observational studies have consistently reported a higher risk of fractures among those with low levels of serum 25-hydroxyvitamin D (25(OH)D). Emerging evidence suggests that low serum 25(OH)D levels may increase the rate of falls through impaired physical function. Examine to what extent baseline measures of volumetric bone mineral density (vBMD), absolute bone mineral content (BMC), and markers of physical function may explain incident hip fractures in older adults with different serum levels of 25(OH)D. A prospective study of 4309 subjects (≥66 years) recruited between 2002 and 2006 into the Age, Gene/Environment Susceptibility-Reykjavik (AGES-Reykjavik) study. Hip fractures occurring until the end of 2012 were extracted from hospital records. Prevalence of serum 25(OH)D deficiency (<30 nmol/L), inadequacy (30-<50 nmol/L), and sufficiency (≥50 nmol/L) was 6%, 23%, and 71% for males; and 11%, 28%, and 53% for females, respectively. Female participants had ~30% lower absolute BMC compared to males. Serum 25(OH)D concentrations were positively associated with vBMD and BMC of the femoral neck and markers of physical function, including leg strength and balance. Those who had deficient compared to sufficient status at baseline had a higher age-adjusted risk of incidence hipfractures with hazard ratios (HRs) of 3.1 (95% confidence interval [CI], 1.9-5.2) and 1.8 (95% CI, 1.3-2.5) among males and females, respectively. When adjusting for vBMD and measures of physical function, the association was attenuated and became nonsignificant for males (1.3; 95% CI, 0.6-2.5) but remained significant for females (1.7; 95% CI, 1.1-2.4). Deficient compared to sufficient serum 25(OH)D status was associated with a higher risk of incident hip fractures. This association was explained by poorer vBMD and physical function for males but to a lesser extent for females. Lower absolute BMC among females due to smaller bone volume may account for these sex-specific differences. © 2021 American Society for Bone and Mineral Research (ASBMR).

Body weight changes and longitudinal associations with cognitive decline among community-dwelling older adults.

INTRODUCTION: We aim to investigate the longitudinal associations between changes in body weight (BW) and declines in cognitive function and risk of mild cognitive impairment (MCI)/dementia among cognitively normal individuals 65 years or older. METHODS: Data from the Age Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik Study) including 2620 participants, were examined using multiple logistic regression models. Cognitive function included speed of processing (SP), executive function (EF), and memory function (MF). Changes in BW were classified as; weight loss (WL), weight gain (WG), and stable weight (SW). RESULTS: Mean follow-up time was 5.2 years and 61.3% were stable weight. Participants who experienced WL (13.4%) were significantly more likely to have declines in MF and SP compared to the SW group. Weight changes were not associated with EF. WL was associated with a higher risk of MCI, while WG (25.3%) was associated with a higher dementia risk, when compared to SW. DISCUSSION: Significant BW changes in older adulthood may indicate impending changes in cognitive function.

Lifestyle and 25-hydroxy-vitamin D among community-dwelling old adults with dementia, mild cognitive impairment, or normal cognitive function.

BACKGROUND: Several studies have indicated that older adults with cognitive impairment have a poorer lifestyle than their healthy peers including lower 25-hydroxy-vitamin D levels (25OHD). AIM: To investigate the associations between lifestyle and 25OHD depending on cognitive status among old adults. METHODS: Community-dwelling old adults (65-96 years) participated in this cross-sectional study based on the Age-Gene/Environment-Susceptibility-Reykjavik-Study. The analytical sample included 5162 subjects who were stratified by cognitive status, i.e., dementia (n = 307), mild cognitive impairment (MCI, n = 492), and normal cognitive status (NCS, n = 4363). Lifestyle variables were assessed and 25OHD was measured. The associations between lifestyle and 25OHD were calculated using linear models correcting for potential confounders. RESULTS: According to linear regression models, 25OHD was significantly lower in older people with dementia (53.8 ± 19.6 nmol/L) than in NCS participants (57.6 ± 17.7 nmol/L). Cod liver oil (7.1-9.2 nmol/L, P < 0.001) and dietary supplements (4.4-11.5 nmol/L, P < 0.001) were associated with higher 25OHD in all three groups. However, physical activity ≥ 3 h/week (2.82 nmol/L, P < 0.001), BMI < 30 kg/m2 (5.2 nmol/L, P < 0.001), non-smoking (4.8 nmol/L, P < 0.001), alcohol consumption (2.7 nmol/L, P < 0.001), and fatty fish consumption ≥ 3x/week (2.6 nmol/L, P < 0.001) were related to higher 25OHD in NCS only, but not in participants with dementia or MCI. DISCUSSION: Older people living in Iceland with dementia are at higher risk for 25OHD deficiency when compared to healthy individuals. Physical activity reported among participants with dementia, and MCI is low and is not significantly associated with 25OHD. CONCLUSIONS: Lifestyle factors among NCS participants are associated with 25OHD levels. Importantly, healthy lifestyle should be promoted among individuals with MCI and dementia.