Genetic and Environmental Influences on Expression of Recurrent Headache as a Function of the Reporting Age in Twins

Preliminary Validation of a General Factor Model of Chronic Overlapping Pain Conditions

Chronic overlapping pain conditions (COPCs) by definition, frequently co-occur, perhaps reflecting their shared etiologies. Their overlapping nature presents a methodological challenge, possibly masking associations between COPCs and health outcomes attributable to either general or specific processes. To address this challenge, we used population-based cohort data to evaluate the predictive validity of a bifactor model of 9 self-reported COPCs by assessing its association with incident pain-related clinical diagnoses; pain-relevant pharmacotherapy; and other health outcomes. We obtained data from a 2005 to 2006 study of Swedish adult twins linked with health data from nationwide registers through 2016 (N = 25,418). We then fit a bifactor model comprising a general COPC factor and 2 independent specific factors measuring pain-related somatic symptoms and neck and shoulder pain. Accounting for age, biological sex, and cancer, the general factor was associated with increased risk of all pain-related outcomes (eg, COPC diagnosis adjusted odds ratio [aOR], 1.71; 95% confidence interval [1.62, 1.81]), most mental health-related outcomes (eg, depression aOR, 1.72 [1.60, 1.85]), and overdose and mortality (eg, all-cause mortality aOR, 1.25 [1.09, 1.43]). The somatic symptoms specific factor was associated with pain-relevant pharmacotherapy (eg, prescribed opioids aOR, 1.25 [1.15, 1.36]), most mental health-related outcomes (eg, depression aOR, 1.95 [1.70, 2.23]), and overdose (eg, nonfatal overdose aOR, 1.66 [1.31, 2.10]). The neck and shoulder pain-specific factor was weakly and inconsistently associated with the outcomes. Findings provide initial support for the validity and utility of a general-factor model of COPCs as a tool to strengthen understanding of co-occurrence, etiology, and consequences of chronic pain. PERSPECTIVE: This article presents associations between a novel measurement model of COPCs and various health outcomes. Findings provide support for measuring pain across multiple domains rather than only measuring pain specific to one physical location in both research and clinical contexts.

Chronic pain conditions and risk of suicidal behavior: a 10-year longitudinal co-twin control study

BACKGROUND

Understanding the relationship between chronic pain conditions and suicidal behavior-suicide attempt, other intentional self-harm, and death by suicide-is imperative for suicide prevention efforts. Although chronic pain conditions are associated with suicidal behaviors, these associations might be attributed to unmeasured confounding or mediated via pain comorbidity.

METHODS

We linked a population-based Swedish twin study (N=17,148 twins) with 10 years of longitudinal, nationwide records of suicidal behavior from health and mortality registers through 2016. To investigate whether pain comorbidity versus specific pain conditions were more important for later suicidal behavior, we modeled a general factor of pain and two independent specific pain factors (measuring pain-related somatic symptoms and neck-shoulder pain, respectively) based on 9 self-reported chronic pain conditions. To examine whether the pain-suicidal behavior associations were attributable to familial confounding, we applied a co-twin control model.

RESULTS

Individuals scoring one standard deviation above the mean on the general pain factor had a 51% higher risk of experiencing suicidal behavior (odds ratio (OR), 1.51; 95% confidence interval (CI), 1.34-1.72). The specific factor of somatic pain was also associated with increased risk for suicidal behavior (OR, 1.80; 95% CI, 1.45-2.22]). However, after adjustment for familial confounding, the associations were greatly attenuated and not statistically significant within monozygotic twin pairs (general pain factor OR, 0.89; 95% CI, 0.59-1.33; somatic pain factor OR, 1.02; 95% CI, 0.49-2.11) CONCLUSION: Clinicians might benefit from measuring not only specific types of pain, but also pain comorbidity; however, treating pain might not necessarily reduce future suicidal behavior, as the associations appeared attributable to familial confounding.

Outcome of Headache Frequency in Adolescence

Only a few studies have been published of the outcome of adolescent headache (HA). The aim of this study was to examine the predictors of the outcome of headache frequency. A population-based sample of 13-year-olds with or without HA ( N = 228) was followed to the age of 16 years. HA was classified on the basis of a face-to-face interview and clinical examination. The outcomes of monthly HA (>1/month) and non-frequent HA (0-1/month) were studied. Frequent use of analgesics, female gender and multiple non-headache pain predicted the persistence of monthly HA (>1/month). Significant predictors for worsening non-frequent HA (from 0 to 1/month to >1/month) were female gender, consistent migraine and high basic educational level of one parent. Adolescents frequently using analgesics constitute a risk group for a poor outcome of HA. Especially girls meeting this criterion should be considered a target group in the planning and implementing of preventive measures.

A prospective study of health, life-style and psychosocial predictors of self-rated health

The aim of this study was to investigate what psychosocial predictors, life-style factors and health behaviors in early adulthood are of importance for self-ratings of health after the age of 45. Like-sexed adult twins born 1926-1950 (n = 16,080) from the Swedish Twin Registry that participated in a questionnaire in 1973 and in a telephone interview conducted between 1998 and 2002 were included. Exposure data was collected in 1973 and information on self-rated health and covariates was collected at the second contact 25 years later. Logistic regression using Generalized Estimating Equations was used to evaluate the associations. Conditional logistic regression was used to control for familial and genetic effects in the sample. Pain, lack of exercise, smoking, obesity, unemployment, perceived stress and personality are associated with future poor self-rated health, after controlling for age, sex, illness, education and socio-economic status. Familial and genetic effects influence the associations between recurrent headache, exercise, obesity, and poor self-rated health. Overall, these findings provide support for long-term effects of health behavior and psychosocial risk factors on poor self-ratings of health, beyond the influence of obvious health consequences such as disorders or illnesses. Genetic and familial factors are of importance only for some of these associations.

Etiology of primary headaches: the importance of genes and environment

Results from twin studies show that genes play an important role for susceptibility to migraine. The propensity for migraine to run in some families but not in others arises predominantly from alleles shared by family members and not the shared family environment, and that environmental influences on migraine are unique to the affected family member. The main genetic and environmental architecture for the other two major primary headaches, tension-type and cluster, remains to be elucidated. This review focuses on recent advances in twin studies of primary headaches and the future prospects are outlined.