Moderating effect of apolipoprotein genotype on loneliness leading to depressive symptoms in Chinese older adults

Cognition in Patients With Memory Difficulties and Dementia Relative to APOE e4 Status

The aim of this study was to investigate whether cognitive performance was equally influenced by Apolipoprotein E (APOE, with its three alleles, e2, e3, and e4) in patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer’s disease (AD). In addition, we examined a group of patients with a combination of Vascular dementia (VaD) and AD (VaD/AD). We asked if the APOE e4 allele influenced cognition in these patient groups in the same way. Our study comprised data from 1,991 patients (55% women), with a mean age of 70.9 years (SD 10.8) and 12.1 years of education (SD 3.8). Of them, 1,111 (56%) had at least one APOE e4 allele; 871 (44%) had one and 240 (12%) had two e4 alleles. Three neurocognitive tests were used to measure cognition: the Mini Mental State Examination (MMSE), the 10-word test of the Consortium to Establish a Registry for Alzheimer’s Disease Word List (CERAD-WL) (immediate and delayed recall), and the Trail Making Test Part A (TMTA). The APOE genotypes were regressed against cognitive function using linear regression, adjusting for diagnosis, age, sex, and education. The interaction diagnosis^∗APOE was investigated. The allele type had the largest effect on cognitive performance assessed by the CERAD-WL delayed recall test, less for the other tests. Those without the e4 type scored 0.7 units better than those with e4 allele(s) (p < 0.001). Furthermore, there was a significant inverse dose-response pattern between number of e4 alleles and cognitive performance; those with one allele scored 0.4 units better than those with two alleles (p = 0.006), and those without e4 scored 0.7 units better than those with one e4 (p < 0.001). This pattern did not differ between the four diagnostic groups studied.

Social Isolation, Loneliness, and All-Cause Mortality in Patients With Cardiovascular Disease: A 10-Year Follow-up Study

OBJECTIVE

Social isolation and loneliness have been associated with increased incidence of cardiovascular disease (CVD), but few studies have evaluated the impact of social isolation and loneliness on mortality in people with existing CVD, and these are limited to Western populations. We examined whether social isolation and loneliness are associated with increased risk of mortality in individuals with established CVD in Taiwan.

METHODS

The cohort was composed of 1267 patients with confirmed CVD 65 years or older followed up for up to 10 years. Cox proportional hazard regression models were used to examine the association between social isolation and loneliness at baseline and mortality at follow-up by adjusting for demographic variables, health-related behaviors, and health status.

RESULTS

There were 593 deaths during the follow-up period. Social isolation was associated with increased risk of mortality after accounting for established risk factors (hazard ratio [HR] = 1.16; 95% confidence interval [CI] = 1.06-1.26), whereas loneliness was not associated with increased risk of mortality (HR = 0.95; 95% CI = 0.82-1.09). When both social isolation and loneliness were included in the model, social isolation maintained an association with mortality (HR = 1.16; 95% CI =1.07-1.27).

CONCLUSIONS

Social isolation is associated with an increased risk of mortality in patients with CVD, and the effects are independent of loneliness. These findings expand our knowledge about the impact of social isolation on the outcomes of CVD in non-Western countries. Efforts to reduce isolation may have substantial benefits in terms of mortality in patients with CVD.

APOE - a genetic marker of comorbidity in subjects with morbid obesity

Background

In population-based studies, the genetic variability of the APOE E alleles have been associated with health outcomes. Health problems are common in subjects with obesity. This study explored associations between the APOE E alleles and comorbidity in subjects with morbid obesity.

Methods

The study included consecutive subjects referred for evaluation of bariatric surgery with morbid obesity (defined as BMI > 40 or > 35 kg/m² with complications related to obesity). The subjects followed a conservative weight loss program for 6 months before surgery and had a follow-up visit 12 months after surgery. Demographic data and a set psychosomatic scores (musculoskeletal pain, WHO-5 Well-Being Index, Rosenberg Self-Esteem Scale, Hopkins Symptom Check-list 10; Epworth Sleepiness Scale, and Fatigue Severity Scale) were collected, and blood samples were analysed for haematological and biochemical parameters and APOE alleles.

Results

One hundred and forty subjects (men/women: 32 (23%)/108 (77%) with mean age 43.0 (SD 8.7) years and BMI 42.1 (SD 3.8) kg/m² were included. One hundred and eight and 92 subjects had data after conservative treatment and 12 months after surgery, respectively. The prevalence of the APOE alleles were: E2E2: 1 (0.7%), E2E3: 13 (9.3%), E2E4: 4 (2.9%), E3E3: 71 (50.7%), E3E4: 47 (33.6%), and E4E4: 4 (2.9%). The prevalence rates were as anticipated in a Norwegian population. The weight loss during conservative treatment and after bariatric surgery was independent of E allele variability. E2 was associated with a significant or clear trend toward improvement of all psychosomatic disorders. There was a significant fall in CRP during the two treatment periods with weight loss. E2 and E4 were significantly associated with high and low CRP, respectively, but no associations were seen between CRP and comorbidity.

Conclusions

The most marked finding was the association between E2 and improvement of all psychosomatic disorders. The positive and negative associations between CRP and E2 and E4, respectively, could indicate effects on inflammation and immunological reactions.

Prospective associations of social isolation and loneliness with poor sleep quality in older adults

PURPOSE

There is evidence for negative associations between social isolation and loneliness and sleep quality in older adults. However, it is unclear to what extent these two factors independently affect sleep quality. This study examined the simultaneous associations of social isolation and loneliness with sleep quality in a longitudinal study of older adults.

METHODS

Data were analyzed from the Social Environment and Biomarkers of Aging Study in Taiwan collected in 2000 and 2006, involving a cohort of 639 participants (mean age = 66.14, SD 7.26). Poisson regression models were conducted to examine the association of social isolation and/or loneliness with sleep quality at follow-up after adjusting for multiple confounding variables.

RESULTS

Univariate analysis showed that sleep quality was inversely associated with both social isolation and loneliness. After demographic, health, cognitive factors, and depressive symptoms were controlled in multivariable analysis, social isolation at the baseline still predicted poor sleep quality 6 years later (incident rate ratio, IRR 1.14; 95% CI 1.04-1.24; p < 0.01), while the association between loneliness and sleep quality was no longer significant (IRR 1.08; 95% CI 0.94-1.23; p = 0.27). The results were unchanged when participants who had poor sleep quality at the baseline were excluded from the analysis.

CONCLUSIONS

These findings confirm an adverse effect of social isolation on the sleep quality of older adults, but indicate that this effect is independent of loneliness. Social isolation and loneliness seem to have distinct pathways in affecting the sleep quality of older adults.

Genome-Wide Association Study of Loneliness Demonstrates a Role for Common Variation

Loneliness is a complex biological trait that has been associated with numerous negative health outcomes. The measurement and environmental determinants of loneliness are well understood, but its genetic basis is not. Previous studies have estimated the heritability of loneliness between 37 and 55% using twins and family-based approaches, and have explored the role of specific candidate genes. We used genotypic and phenotypic data from 10 760 individuals aged ⩾50 years that were collected by the Health and Retirement Study (HRS) to perform the first genome-wide association study of loneliness. No associations reached genome-wide significance (p>5 × 10^-8). Furthermore, none of the previously published associations between variants within candidate genes (BDNF, OXTR, RORA, GRM8, CHRNA4, IL-1A, CRHR1, MTHFR, DRD2, APOE) and loneliness were replicated (p>0.05), despite our much larger sample size. We estimated the chip heritability of loneliness and examined coheritability between loneliness and several personality and psychiatric traits. Our estimates of chip heritability (14-27%) support a role for common genetic variation. We identified strong genetic correlations between loneliness, neuroticism, and a scale of 'depressive symptoms.' We also identified weaker evidence for coheritability with extraversion, schizophrenia, bipolar disorder, and major depressive disorder. We conclude that loneliness, as defined in this study, is a modestly heritable trait that has a highly polygenic genetic architecture. The coheritability between loneliness and neuroticism may reflect the role of negative affectivity that is common to both traits. Our results also reflect the value of studies that probe the common genetic basis of salutary social bonds and clinically defined psychiatric disorders.

Obesity, Apolipoprotein E ε4, and Difficulties in Activities of Daily Living Among Older Adults: a 6-Year Follow-up Study

BACKGROUND

Obesity has been associated with increased physical limitations among older adults, although few studies have adjusted for important covariates. There is limited information about the relationship between apolipoprotein E (APOE) polymorphisms and physical limitations, and the findings have been inconsistent.

PURPOSE

This study examined the longitudinal associations of obesity and APOE ε4 with difficulties in activities of daily living (ADLs) over a 6-year follow-up period controlling for multiple covariates.

METHODS

Data were analyzed from the Social Environment and Biomarkers of Aging Study (SEBAS) in Taiwan collected in 2000 and 2006, involving a cohort of 639 participants (mean age = 66). Body mass index (BMI) was used to define obesity at a baseline, and the APOE genotype was classified into an APOE ε4 carrier and non-carrier status. The combination of basic and instrumental activities of daily living (ADLs and IADLs) was used to define impaired ADLs.

RESULTS

APOE ε4 carriers had greater difficulties in combined ADLs (incident rate ratio; IRR = 1.87, 95 % CI = 1.40-2.51) than non-carriers. Obese but not overweight adults had greater difficulties in activities of daily living (IRR = 1.59, 95 % CI = 1.20-2.10) compared with the normal/underweight group. Obese older adults without APOE ε4 had greater subsequent difficulties in ADLs than non-obese non-carriers. Among APOE ε4 carriers, obesity was not a significant risk factor for the development of impaired ADLs in older adults, indicating an interaction between genotype and obesity.

CONCLUSIONS

The interaction between genotype and obesity phenotype adds new information about the determinants of physical impairment.

Social isolation, loneliness and depression in young adulthood: a behavioural genetic analysis

PURPOSE

To investigate the association between social isolation and loneliness, how they relate to depression, and whether these associations are explained by genetic influences.

METHODS

We used data from the age-18 wave of the Environmental Risk Longitudinal Twin Study, a birth cohort of 1116 same-sex twin pairs born in England and Wales in 1994 and 1995. Participants reported on their levels of social isolation, loneliness and depressive symptoms. We conducted regression analyses to test the differential associations of isolation and loneliness with depression. Using the twin study design, we estimated the proportion of variance in each construct and their covariance that was accounted for by genetic and environmental factors.

RESULTS

Social isolation and loneliness were moderately correlated (r = 0.39), reflecting the separateness of these constructs, and both were associated with depression. When entered simultaneously in a regression analysis, loneliness was more robustly associated with depression. We observed similar degrees of genetic influence on social isolation (40 %) and loneliness (38 %), and a smaller genetic influence on depressive symptoms (29 %), with the remaining variance accounted for by the non-shared environment. Genetic correlations of 0.65 between isolation and loneliness and 0.63 between loneliness and depression indicated a strong role of genetic influences in the co-occurrence of these phenotypes.

CONCLUSIONS

Socially isolated young adults do not necessarily experience loneliness. However, those who are lonely are often depressed, partly because the same genes influence loneliness and depression. Interventions should not only aim at increasing social connections but also focus on subjective feelings of loneliness.

The genetics of loneliness: linking evolutionary theory to genome-wide genetics, epigenetics, and social science

As a complex trait, loneliness is likely to be influenced by the interplay of numerous genetic and environmental factors. Studies in behavioral genetics indicate that loneliness has a sizable degree of heritability. Candidate-gene and gene-expression studies have pointed to several genes related to neurotransmitters and the immune system. The notion that these genes are related to loneliness is compatible with the basic tenets of the evolutionary theory of loneliness. Research on gene-environment interactions indicates that social-environmental factors (e.g., low social support) may have a more pronounced effect and lead to higher levels of loneliness if individuals carry the sensitive variant of these candidate genes. Currently, there is no extant research on loneliness based on genome-wide association studies, gene-environment-interaction studies, or studies in epigenetics. Such studies would allow researchers to identify networks of genes that contribute to loneliness. The contribution of genetics to loneliness research will become stronger when genome-wide genetics and epigenetics are integrated and used along with well-established methods in psychology to analyze the complex process of gene-environment interplay.

Frequencies of apolipoprotein E alleles in depressed patients undergoing hemodialysis--a case-control study

OBJECTIVE

To explore the relation between the frequencies of apolipoprotein E (ApoE) alleles and the occurrence of depression in patients undergoing hemodialysis in a Chinese population.

METHODS

We examined the ApoE alleles in a sample of 288 subjects: 72 patients with depression under hemodialysis, 74 patients without depression under hemodialysis, 75 patients with depression under nondialytic treatment and 67 patients without depression under nondialytic treatment. The depression state was assessed using the Center for Epidemiological Studies Depression (CES-D) scale. Associations between the occurrence of depression and the frequencies of ApoE alleles were examined using multinomial logistic regression models with adjustment of relevant covariates. Information about sociodemographics, clinical data, vascular risk factors and cognitive function was also collected and evaluated.

RESULTS

The frequencies of ApoE-ɛ2 were significantly different between depressed and non-depressed patients irrespective of dialysis (p < 0.05), but no significant difference was found in the frequencies of ApoE-ɛ4 (p > 0.05). Serum ApoE levels were significantly different between depressed and non-depressed patients in the whole sample (p < 0.05). Multinomial logistic regression models showed significant association between the frequency of ApoE-ɛ2 and the occurrence of depression in the Chinese population after control of relevant covariates, including age, sex, educational level, history of smoking and drinking, vascular risk factors and cognitive function.

CONCLUSIONS

No association between the frequency of ApoE-ɛ4 and the occurrence of depression was found in patients undergoing hemodialysis. Further research is needed to find out if ApoE-ɛ2 acts as a protective factor in Chinese dialysis population since it might decrease the prevalence of depression and delay the onset age.

Influence of social environment on loneliness in older adults: Moderation by polymorphism in the CRHR1

OBJECTIVE

Both adverse social environments and genetic factors contribute to loneliness in old age. Mixed findings between older adults' social relations with their children and their levels of loneliness suggested that a gene × social environment interaction may be operating. We examine whether the effects of infrequent contact with children and low levels of perceived social support from children on loneliness in older adults are moderated by two candidate single nucleotide polymorphisms (i.e., rs1876831 and rs242938) in the corticotrophin releasing hormone receptor 1 (CRHR1) gene.

DESIGN

This was a longitudinal observational study.

SETTING

and

PARTICIPANTS

A population-based sub-sample of 1,374 community-dwelling older adults aged 65 years and older was examined from both the 2003-2004 and 2006-2007 English Longitudinal Study of Aging assessments.

MEASUREMENTS

Our main outcome measure is loneliness, which was assessed by four items extracted from the ULCA loneliness scale.

RESULTS

Compared with older adults carrying the CT/TT genotypes, individuals homozygous for the C allele of rs1876831 reported higher levels of loneliness in the context of infrequent social contact with children and lower levels of perceived social support from children. No gene × social environment interactions were found for loneliness between rs242938 and an adverse social environment related to children.

CONCLUSIONS

This study provides the first evidence in humans that the CRHR1 gene interacts with exposure to a negative social environment to predict loneliness in older adults.

APOE ϵ4, rated life experiences, and affect among centenarians

OBJECTIVES

The purpose of this study was to assess the relationship between apolipoprotein E (APOE), life events and engagement, and subjective well-being (as measured by positive and negative affect) among centenarians. Based on the life stress paradigm, we predicted that higher levels of stress would allow APOE to influence positive and negative affect.

METHOD

196 centenarians and near-centenarians (98 years and older) of the Georgia Centenarian Study participated in this research. The APOE, positive and negative affect, the number of recent (last 2 years) and lifelong (more than 20 years prior to testing) events, as well as a number of life engagement tasks were assessed.

RESULTS

Results suggested that centenarians carrying the APOE ϵ4 allele rated lower in positive affect, the number of lifelong events, and in engaged lifestyle, when compared to centenarians without the APOE ϵ4 allele (t = 3.43, p < .01; t = 3.19, p < .01; and t = 2.33, p < .05, respectively). Blockwise multiple regressions indicated that the APOE ϵ4 predicted positive but not negative affect after controlling for demographics. Gene-environment interactions were obtained for the APOE ϵ4 and lifelong events, suggesting that carriers of the APOE ϵ4 allele had higher scores of negative affect after having experienced more events, whereas noncarriers had reduced negative affect levels after having experienced more events.

CONCLUSION

APOE ϵ4 is directly related to positive affect and is related to negative affect in interaction with life events.

Gene environment interaction studies in depression and suicidal behavior: An update

Increasing evidence supports the involvement of both heritable and environmental risk factors in major depression (MD) and suicidal behavior (SB). Studies investigating gene-environment interaction (G × E) may be useful for elucidating the role of biological mechanisms in the risk for mental disorders. In the present paper, we review the literature regarding the interaction between genes modulating brain functions and stressful life events in the etiology of MD and SB and discuss their potential added benefit compared to genetic studies only. Within the context of G × E investigation, thus far, only a few reliable results have been obtained, although some genes have consistently shown interactive effects with environmental risk in MD and, to a lesser extent, in SB. Further investigation is required to disentangle the direct and mediated effects that are common or specific to MD and SB. Since traditional G × E studies overall suffer from important methodological limitations, further effort is required to develop novel methodological strategies with an interdisciplinary approach.

Impact of marital status and race on outcomes of patients enrolled in Radiation Therapy Oncology Group prostate cancer trials

INTRODUCTION

Previous studies by our group and others have demonstrated the importance of sociodemographic factors in cancer-related outcomes. The identification of these factors has led to novel approaches to the care of the high-risk cancer patient, specifically in the adoption of clinical interventions that convey similar benefits as favorable sociodemographic characteristics. This study examined the importance of marital status and race as prognostic indicators in men with prostate cancer.

METHODS

This report is a meta-analysis of 3,570 patients with prostate cancer treated in three prospective RTOG clinical trials. The Kaplan-Meier method was used to estimate the survival rate and the cumulative incidence method was used to analyze biochemical failure rate. Hazard ratios were calculated for all covariates using either the Cox or Fine and Gray's proportional hazards model or logistic regression model with associated 95% confidence intervals and p values.

RESULTS

Hazard ratio (HR) for overall survival (OS) for single status compared to married status was 1.36 (95% CI, 1.2 to 1.53). OS HR for non-White compared to White patients was 1.05 (CI 0.92 to 1.21). In contrast, the disease-free survival (DFS) HR and biochemical failure (BF) HR were both not significantly different neither between single and married patients nor between White patients and non-White patients. Median time to death for married men was 5.68 years and for single men was 4.73 years. Median time for DFS for married men was 7.25 years and for single men was 6.56 years. Median time for BF for married men was 7.81 years and for single men was 7.05 years.

CONCLUSIONS

Race was not associated with statistically significant differences in this analysis. Congruent with our previous work in other cancer sites, marital status predicted improved prostate cancer outcomes including overall survival.

IMPLICATIONS FOR CANCER SURVIVORS

Prostate cancer is the most common visceral cancer in men in the USA. The stratification of prostate cancer risk is currently modeled solely on pathologic prognostic factors including PSA and Gleason Score. Independent of these pathologic prognostic factors, our paper describes the central sociodemographic factor of being single as a negative prognostic indicator. Single men are at high risk of poorer outcomes after prostate cancer treatment. Intriguingly, in our group of patients, race was not a significant prognostic factor. The findings in this paper add to the body of work that describes important sociodemographic prognostic factors that are currently underappreciated in patients with cancer. Future steps will include the validation of these findings in prospective studies, and the incorporation of clinical strategies that identify and compensate for sociodemographic factors that predict for poorer cancer outcomes.