Parental Multisite Chronic Pain and the Risk of Adult Offspring Developing Additional Chronic Pain Sites: Family-Linkage Data From the Norwegian HUNT Study

Multisite chronic pain and the risk of autoimmune diseases: A Mendelian randomization study

Background

Accumulating evidence has demonstrated that an association between chronic pain and autoimmune diseases (AIDs). Nevertheless, it is unclear whether these associations refer to a causal relationship. We used a two-sample Mendelian randomization (MR) method to determine the causal relationship between chronic pain and AIDs.

Methods

We assessed genome-wide association study (GWAS) summary statistics for chronic pain [multisite chronic pain (MCP) and chronic widespread pain (CWP)], and eight common AIDs, namely, amyotrophic lateral sclerosis (ALS), celiac disease (CeD), inflammatory bowel disease (IBD), multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus Erythematosus (SLE), type 1 diabetes (T1D) and psoriasis. Summary statistics data were from publicly available and relatively large-scale GWAS meta-analyses to date. The two-sample MR analyses were first performed to identify the causal effect of chronic pain on AIDs. The two-step MR and multivariable MR were used to determine if mediators (BMI and smoking) causally mediated any connection and to estimate the proportion of the association mediated by these factors combined.

Results

With the utilization of MR analysis, multisite chronic pain was associated with a higher risk of MS [odds ratio (OR) = 1.59, 95% confidence interval (CI) = 1.01-2.49, P = 0.044] and RA (OR = 1.72, 95% CI = 1.06-2.77, P = 0.028). However, multisite chronic pain had no significant effect on ALS (OR = 1.26, 95% CI = 0.92-1.71, P = 0.150), CeD (OR = 0.24, 95% CI = 0.02-3.64, P = 0.303), IBD (OR = 0.46, 95% CI = 0.09-2.27, P = 0.338), SLE (OR = 1.78, 95% CI = 0.82-3.88, P = 0.144), T1D (OR = 1.15, 95% CI = 0.65-2.02, P = 0.627) or Psoriasis (OR = 1.59, 95% CI = 0.22-11.26, P = 0.644). We also found positive causal effects of MCP on BMI and causal effects of BMI on MS and RA. Moreover, there were no causal connections between genetically predicted chronic widespread pain and the risk of most types of AIDs disease.

Conclusion

Our MR analysis implied a causal relationship between MCP and MS/RA, and the effect of MCP on MS and RA may be partially mediated by BMI.

Primary dysmenorrhoea in adolescents and young women: A twin family study of maternal transmission, genetic influence and associations

AIMS

The extent to which maternal transmission of primary dysmenorrhoea is genetically determined in adolescents and young women has yet to be determined. We aimed to assess heritability and associations relevant to primary pain syndromes using a twin family study.

METHODS

Participants were young menstruating female twins, and their oldest sisters and mothers, whose families were registered with Twins Research Australia and previously participated in a twin family study of primary paediatric pain disorders. Questionnaire packs were mailed, assessing current maximum and average menstrual pain intensity, current pain interference with activities and retrospective dysmenorrhea secondary symptoms.

RESULTS

The sample comprised 206 twin individuals (57 monozygous (MZ) and 46 dizygous (DZ) pairs) aged 10-22 years, eldest siblings (n = 38) aged 13-28 years and mothers (n = 101) aged 32-61 years. The estimated regression coefficient of the relationship between mother-daughter and twin-sibling dyads indicated significant associations for the measures of dysmenorrhea and supported heritability. Adjusted for age, the within twin-pair correlation for MZ twins was generally more than twice that of DZ twins. Heritability estimates were maximal pain intensity 0.67 (P = 3.8 × 10^-11 ), average pain intensity 0.63 (P = 3.7 × 10^-10 ), pain interference 0.57 (P = 1.8 × 10^-8 ) and retrospective symptoms 0.57 (P = 1.8 × 10^-8 ). Twin individuals with a lifetime (three-month) history of iron deficiency and those with painless restless legs syndrome (RLS) were significantly more likely to have more intense pain associated with menstruation.

CONCLUSION

Primary dysmenorrhea in adolescents and young women was shown to be relatively strongly genetically influenced and associated especially with a history of iron deficiency and painless RLS which have potential therapeutic implications.

Familial and Genetic Influences on the Common Pediatric Primary Pain Disorders: A Twin Family Study

The primary pain disorders of childhood are highly prevalent but have infrequently been studied collectively. Genetic influences have been suggested to be causally implicated. Surveys were sent to 3909 Australian twin families, assessing the lifetime prevalence of growing pains, migraine, headache, recurrent abdominal pain, low back pain, and persistent pain (not otherwise specified) in pediatric twins and their immediate family members. Comparisons between monozygous (MZ) and dizygous (DZ) twin pair correlations, concordances and odds ratios were performed to assess the contribution of additive genetic influences. Random-effects logistic regression modelling was used to evaluate relationships between twin individuals and their co-twins, mothers, fathers and oldest siblings with the subject conditions. Twin analyses of responses from 1016 families revealed significant influence of additive genetic effects on the presence of growing pains, migraine, and recurrent abdominal pain. The analyses for headache, low back pain, and persistent pain overall did not conclusively demonstrate that genetic influences were implicated more than shared environmental factors. Regression analyses demonstrated varying levels of significance in relationships between family members and twin individuals for the tested conditions, with strongest support for genetic influences in growing pains and migraine. These data, together with previously published association analyses, suggest common causal influences including genes.

Baseline Characteristics of a Dyadic Cohort of Mothers With Chronic Pain and Their Children

OBJECTIVES

A growing body of research has demonstrated a robust link between parental chronic pain and child pain and psychological function. Although the association between parent and child pain is strong, there are limited data to understand environmental and behavioral processes that account for the association and how this develops over time. This longitudinal cohort study was designed to understand the potential mechanisms that confer risk or resilience for chronic pain among child offspring of mothers with chronic pain.

METHODS

The current paper presents baseline data on the cohort to describe the pain and psychosocial characteristics of mothers with chronic pain and their 8- to 12-year-old children. A total of 400 mothers with chronic pain and their children were enrolled into the longitudinal study and completed measures of pain, physical, and psychosocial functioning.

RESULTS

Mothers reported a range of pain and pain-related disability and were grouped into 4 pain grades (PGs) representing different pain and disability levels. Mothers in these groups differed on rates of widespread pain and opioid use. Maternal PGs also differed by physical function, fatigue, sleep disturbance, and psychological function. Most children in this sample reported pain and psychosocial symptoms in the nonclinical range, and child variables did not differ by maternal PG. Maternal disability and function were concurrently associated with child psychosocial function.

DISCUSSION

While maternal PGs map broadly onto several dimensions of maternal functioning, they were not significantly related to child pain or function. Results may help identify potential protective factors in the intergenerational transmission of risk for chronic pain.