Comorbidity and familial aggregation of back/neck pain in the NIMH Family Study of Affective Spectrum Disorders

Objective: Back pain is associated with substantial Global Burden of Disease and is highly comorbid with mood and anxiety symptoms and syndromes. However, mechanisms underlying this association have not been well-elucidated. Here we apply data from the NIMH Family Study of Affective Spectrum Disorders to investigate the comorbidity, familial aggregation, and cross-aggregation of back/neck pain with mood disorder subtypes. Methods: The sample includes 519 probands and 560 interviewed first-degree relatives. Lifetime DSM-IV Bipolar I, Bipolar II, and Major Depressive Disorder [MDD] were derived from semi-structured diagnostic interviews. Lifetime history of back or neck pain and its age of onset were self-reported retrospectively. Familial aggregation and cross-aggregation were estimated via mixed effects models in probands and interviewed first-degree relatives, while heritability and co-heritability (endophenotypic ranking value [ERV]) were estimated using full pedigrees. Results: Over 45% of participants endorsed a history of back/neck pain. Back/neck pain was familial (adjusted odds ratio [aOR] 1.5, p = 0.04; h2 = 0.24, p = 0.009). Back/neck pain in probands was associated with MDD in relatives (aOR 1.5, p = 0.04; ERV = 0.17, p = 0.024), but not with bipolar disorder. Onset of back/neck pain occurred earlier in those with bipolar disorder compared to controls. Conclusion: Findings suggest common familial risk factors underlying back/neck pain with MDD, whereas there was within-individual comorbidity of bipolar with back/neck pain. Future studies that identify common factors that lead to either back/neck pain or MDD can inform prevention and interventions.

Automated summary

Back pain is highly associated with mood and anxiety symptoms and syndromes, but the underlying mechanisms are still unclear. This study found a familial aggregation of back/neck pain with Major Depressive Disorder (MDD), but not with bipolar disorder. Onset of back/neck pain occurred earlier in individuals with bipolar disorder compared to controls.