Adversity over the life course: assessment and quantification issues

The association between adverse life events and body weight change: results of a prospective cohort study

BACKGROUND

Stress has been shown to be a determinant of weight change and risk for obesity. To date, there is scarce evidence that stressful life events and their severity contribute to changes in body weight. We studied the association between the occurrence, impact of and adaptation to adverse life events and weight change and the role of initial weight status.

METHODS

Analyses were based on data from a population-based cohort of 2789 adults. Adverse life events, their impact and adaptation were measured retrospectively after baseline and follow-up weight and height measurements.

RESULTS

Over six years, participants gained an average of 2.8 kg. There were no differences in weight change between those who had experienced an adverse life event versus those who had not. However, the impact of life events had a significant interaction with initial weight status. Adults with a healthy weight showed an average weight reduction of 0.2 kg (95% CIs: -0.7 - 0.2), and overweight adults showed an average weight gain of 0.4 kg (95% CIs: -0.3 - 1.1) for each point increase in impact after experiencing an adverse life event. Further, a slower adaptation to events was significantly associated with greater weight loss among those who lost weight.

CONCLUSIONS

We found no proof for an association between life events and weight change in the entire study sample, but we found that adults at a healthy weight responded differently to adverse life events than those who were overweight.

Validation of the Long-term Difficulties Inventory (LDI) and the List of Threatening Experiences (LTE) as measures of stress in epidemiological population-based cohort studies

BACKGROUND

Stress questionnaires are included in many epidemiological cohort studies but the psychometric characteristics of these questionnaires are largely unknown. The aim of this study was to describe these characteristics for two short questionnaires measuring the lifetime and past year occurrence of stress: the List of Threatening Events (LTE) as a measure of acute stress and the Long-term Difficulties Inventory (LDI) as a measure of chronic stress.

METHOD

This study was performed in a general population cohort consisting of 588 females (53.7%) and 506 males (46.3%), with a mean age of 53.5 years (s.d.=11.3 years). Respondents completed the LTE and the LDI for the past year, and for the age categories of 0-12, 13-18, 19-39, 40-60, and >60 years. They also completed questionnaires on perceived stress, psychological distress (the General Health Questionnaire, GHQ-12), anxiety and depression (the Symptom Checklist, SCL-8) and neuroticism (the Eysenck Personality Questionnaire - Revised Short Scale, EPQ-RSS-N). Approximately 2 years later, 976 respondents (89%) completed these questionnaires for a second time.

RESULTS

The stability of the retrospective reporting of long-term difficulties and life events was satisfactory: 0.7 for the lifetime LDI and 0.6 for the lifetime LTE scores. The construct validity of these lists is indicated by their positive associations with psychological distress, mental health problems and neuroticism.

CONCLUSIONS

This study in a large population-based sample shows that the LDI and LTE have sufficient validity and stability to include them in major epidemiological cohort studies.

The shackles of misfortune: Social adversity assessment and representation in a chronic-disease epidemiological setting

Research evidence is accumulating to support an association between social adversity and the development of predisease processes and physical disease outcomes. While methodological advances have been achieved in the assessment of social adversity, significant barriers remain to their adoption in chronic disease epidemiological settings consequent upon the need to limit participant burden and restrictions imposed by cohort size and cost. A large-scale population-based cohort study, as part of the European Prospective Investigation into Cancer, Norfolk, UK, provided an opportunity to include a comprehensive postal assessment of social adversity. A total of 20,921 participants reported details of 16,031 adverse circumstances during childhood, 119,056 life events and 106,170 person-years of difficulties experienced during adulthood. Impact and adaptation indices were constructed from responses to questions regarding specific life events experienced. There was no evidence that younger participants reported more difficulties in childhood than those who were older, and no evidence of clustering of loss events involving the death of first degree relatives according to their recency. However, there was evidence of recall bias for events not involving loss with increased event rates observed in the few years immediately prior to questionnaire completion. Women reported similar events as more upsetting, and that they took longer to get over their effects, than men. Difficulties experienced in childhood, life events and difficulties in adulthood, event impact and adaptation were all associated with worse physical functional health. Reported slow adaptation to the effects of life events was associated with the largest decrement in physical functional health. These findings strengthen the rationale for including a collection of comprehensive social adversity data within chronic disease epidemiological settings and offer promise for aiding understanding of individual differences in physical disease aetiology.

Social adversity, the serotonin transporter (5-HTTLPR) polymorphism and major depressive disorder

BACKGROUND

Recent evidence has suggested that the short allele of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR of the human serotonin gene [SLC6A4]) is associated with increased risk of depressive disorder but only among individuals exposed to social adversity. We report an investigation designed to replicate this finding.

METHODS

Data were available from a non-clinical sample of 4,175 adult men and women, ages 41-80 years, selected from participants in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk, United Kingdom) study. Evidence of past-year prevalent episodic major depressive disorder (MDD), defined by restricted DSM-IV diagnostic criteria, was assessed through questionnaire. Adverse experiences in childhood and in adulthood (during the five years preceding assessment) were also assessed through self-report. The 5-HTTLPR variant was genotyped according to published protocols.

RESULTS

One-year prevalent MDD criteria were met by 298 study participants. The experience of social adversity (both in childhood and adulthood) was strongly associated with increased rates of past-year prevalent MDD. No gene by environment (GxE) interactions between the 5-HTTLPR genotype, social adversity, and MDD were observed.

CONCLUSIONS

This study has not replicated a previous finding of a GxE interaction between the 5-HTTLPR genotype, social adversity, and depression.

Are stress related factors associated with alcohol intake?

Moderate alcohol consumption is related to reduced risks of coronary heart disease and all-cause mortality. Our goal is to advance our understanding of the associations between stress-related factors and alcohol consumption, using cutoff points for alcohol intake that reflect health benefits rather than health risks. Cross-sectional data were used from 4,131 respondents (age 20-65 years) participating in a cohort study in the Netherlands on psychosocial factors and cancer risk. Analyses were performed among drinkers only, for men and women separately. Heavy alcohol intake (>/= 3 glasses per day for men, >/= 2 glasses per day for women) was associated with only a few stress-related factors in multivariate analyses. No significant associations between the total amount of stressors and alcohol intake were found. We conclude that stress-related factors are only marginally associated with a heavy alcohol intake compared with fair drinking, using the safe limits of drinking as cutoff point.

Time-varying exposure and the impact of stressful life events on onset of affective disorder

Stressful life events are now established as risk factors for the onset of affective disorder but few studies have investigated time-varying exposure effects. Discrete (grouped) time survival methods provide a flexible framework for evaluating multiple time-dependent covariates and time-varying covariate effects. Here, we use these methods to investigate the time-varying influence of life events on the onset of affective disorder. Various straightforward time-varying exposure models are compared, involving one or more (stepped) time-dependent covariates and time-dependent covariates constructed or estimated according to exponential decay. These models are applied to data from two quite different studies. The first, a small scale interviewer-based longitudinal study (n = 180) concerned with affective disorder onset following loss (or threat of loss) event experiences. The second, a questionnaire assessment as part of an ongoing population study (n = 3353), provides a history of marital loss events and of depressive disorder onset. From the first study the initial impact of loss events was found to decay with a half-life of 5 weeks. Psychological coping strategy was found to modify vulnerability to the adverse effects of these events. The second study revealed that while men had a lower immediate risk of disorder onset following loss event experience their risk period was greater than for women. Time-varying exposure effects were well described by the appropriate use of simple time-dependent covariates.

Lifestyle risk factors for cancer: the relationship with psychosocial work environment

BACKGROUND

Psychosocial work characteristics (job demands, control, support, job strain and iso-strain [high job strain combined with social isolation at work]) may be linked to cancer risk, by affecting cancer-related lifestyles like smoking, high alcohol consumption, low intake of fruits and vegetables and lack of physical activity.

METHODS

Cross-sectional data obtained from 3309 respondents participating in an ongoing prospective cohort study in the Netherlands on psychosocial factors and cancer risk were used to study the association between psychosocial job characteristics and lifestyle. Information on job characteristics and risk factor prevalence was collected from 20-65-year-old men and women, through self-administered questionnaires. Multiple logistic and linear regression analyses were undertaken by gender, with adjustment for age and education.

RESULTS

No differences in the prevalence of lifestyle risk factors for cancer were found amongst the psychosocial work characteristics studied. Moreover, little evidence was found for a relation between job (or iso-) strain and cancer-related lifestyles in multivariate analyses.

CONCLUSIONS

The present study found no support for the hypothesis that job strain or iso-strain are associated with a cancer-related lifestyle. Further research on the role of other psychosocial factors-like personality or social support outside work-in mediating associations between job characteristics and lifestyle, is warranted.