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 (β = - 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.

Social Participation and the Risk for Developing Mild Cognitive Impairment and Dementia Among Older Adults

Introduction: We aim to investigate the longitudinal associations between social participation and the risk of developing mild cognitive impairment (MCI|) and dementia over 5 years of follow-up among cognitively normal older adults. Methods: A total of 2802 participants had complete follow-up data from Age-Gene/Environment-Susceptibility-Reykjavik-Study. Social participation was assessed by a questionnaire asking the frequency of contact with children, relatives, friends and neighbors. MCI and dementia were diagnosed according to international guidelines and by a team composed of a geriatrician, neurologist, neuropsychologist, and neuroradiologist. Logistic regression analysis was used to assess the associations. Results: At baseline 8% (n=225) reported no social participation. Among cognitively normal participants at baseline, 5.6% (n=243) developed mild cognitive impairment and 2.4% (n= 103) developed dementia during a mean follow-up time of 5.2 years. After full adjustment with covariates including age, gender, education, marital status, vitamin D levels, depression and APOE ε4, those with no social participation at baseline were significantly more likely to develop MCI at follow-up (OR=1.953, P=0.001). However, social participation at baseline was not associated with higher dementia diagnosis at follow-up (OR= 1.490, P=0.194). Conclusions: Community-dwelling old adults who are socially inactive are more likely to develop MCI than those who are socially active. Social participation might independently indicate impending changes in cognitive function among older adults.

The Association between Leisure and Physical Activity Level with Depressive Symptoms after 5-years of follow-up

BACKGROUND: Depressive symptoms in older adults are associated with socioeconomic status (SES), medical care, and physical activity. However, there is little evidence on the longitudinal association between level of leisure activity (LA) and physical activity (PA) with depressive symptoms among community-dwelling older adults in Iceland. The study examined an association of LA and PA at baseline with high depressive symptoms (HGDS) assessed after 5 years of follow-up among community-dwelling older adults. METHODS: A large community-based population residing in Reykjavik, Iceland participated in a longitudinal study with 5 years of follow-up (n=2957, 58% women, 74.9±4.8 yrs). Those with HGDS or dementia at baseline were excluded from the analysis. The reported activity was categorized into 2 groups as no-activity versus any-activity. Depressive symptoms were assessed by the 15-item Geriatric Depression Scale (GDS) on average 5 years later. RESULTS: After adjusting for demographic and health-related risk factors, those who reported having any LA had significantly fewer HGDS after the follow-up of 5 years (6 or higher GDS scores, Odds Ratio (OR) = 0.46, 95% Confidence Interval (CI): 0.27 ~ 0.76, P = 0.003). However, reporting any PA at baseline was not significantly associated with HGDS (OR = 0.71, 95% CI: 0.51 ~ 1.00, P = 0.053). CONCLUSION: Our study shows that any LA among older adults is associated with having less depressive symptoms 5 years later among community-dwelling older adults while having any PA was not associated with depressive symptoms after 5 years of follow-up.

The Association Between Midlife Education and Depressive Symptoms in Late Life: The AGES-Reykjavik Study

BACKGROUND: Disability and depression are associated with cumulative health adversities such as socioeconomic status (SES), nutrition, medical care, and education among older adults. However, there is little evidence on the longitudinal association between mid-life education level with a disability and depressive symptoms in older adults in Iceland. The aim of the study was to examine the association between mid-life education and prevalence of activity of daily living (ADL) dependency and high depressive symptoms in late-life. METHODS: A large community-based population residing in Reykjavik, Iceland (n=4991, 57.3% women, 76.9±5.8 yrs) participated in a longitudinal study with an average of 25 years of follow-up. Mid-life education was categorized into 4 groups (primary, secondary, college, and university). ADL dependency and high depressive symptoms were assessed on average 25 (±4) years later. The 5-item ADL dependency score ranged between 0 (no difficulty) and 18. Depressive symptoms were assessed by the 15-item Geriatric Depression Scale (GDS). RESULTS: After controlling for demographic and health-related risk factors, those with higher education at mid-life were significantly less likely to have high depressive symptomatology (6 or higher GDS scores, Odds Ratio (OR) = 0.65, 95% Confidence Interval (CI): 0.52 ~ 0.82, P < 0.0001). However, mid-life education was not associated with ADL dependency in later life. CONCLUSION: Our study shows that mid-life education is associated with depressive symptoms 25 years later, while no association found with ADL dependency among Icelandic older adults.

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.

LONGITUDINAL ASSOCIATION BETWEEN SERUM 25 HYDROXY VITAMIN D AND COGNITIVE FUNCTION AMONG ICELANDIC OLDER ADULTS

Studies have indicated that low levels of serum 25 hydroxy vitamin D (25OHD) are associated with lower cognitive function among older adults while longitudinal studies have revealed controversial results. The aim was to investigate the longitudinal associations between 25OHD and cognitive function among older adults with 5-years follow up. The Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study (N=3411) assessed cognitive function measuring memory function, speed of processing and executive function. 25OHD was measured using the Liaison chemiluminescence immunoassay and used as a continuous variable. Multivariate linear analysis, adjusting for numerous confounding factors, was used to calculate the longitudinal associations. All analyses were performed separated by gender. There was a high tendency for low levels of 25OHD i.e. 29.6% men and 37.7% women had hypovitaminosis D (<50 nmol/l). Both men and women had significantly lower scores in all aspects of cognitive function at the follow-up time period. Unadjusted correlations between 25OHD and cognitive functions showed a stronger correlation for women, whereas women had lower scores in all aspects of cognitive function associated with low 25OHD. After adjusting for potential confounders, e.g. age, education, lifestyle and health-related factors, 25OHD and cognitive function were not significantly associated. Observational studies indicate that lower levels of vitamin D are associated with lower cognitive function. Intervention studies are yet to show a clear benefit from vitamin D supplementation. More longitudinal- and interventional studies, with longer follow-up duration, are needed.