Facets of neuroticism and musculoskeletal symptoms. A study of middle-aged twins

• Published in: Norsk epidemiologi Vol. 26; no. 1-2
• Main Authors: Vassend, Olav, Orvik, Benedicte Humborstad, Czajkowski, Nikolai Olavi, Røysamb, Espen
• Format: Journal Article
• Language: English
• Published: Norsk Forening for Epidemiologi 20-07-2016
• ISSN: 0803-2491
• DOI: 10.5324/nje.v26i1-2.2015

Clinical and epidemiological studies have shown that both site-specific and more widespread musculoskeletal(MS) conditions are linked to anxiety and depression symptoms. However, the nature of this relationship ispoorly understood, particularly in terms of underlying genetic and environmental influences. Furthermore, thepersonality trait neuroticism has been shown to be related to common emotional symptoms and somaticdistress as well as to more serious psychiatric and medical disorders. In modern personality theory, the broadneuroticism domain is conceptualized as consisting of a set of lower-order facets, such as anxiety, hostility,and depression, which may be differentially related to various health outcome measures. So far, the role ofneuroticism facets as risk factors for MS conditions has not been explored in genetically informative designs.In the current study, the relationship between MS symptoms and six neuroticism facets was investigated inbivariate analyses and in regression models including sex, education level, and general health indices ascontrol variables. Using multivariate twin modeling, genetic and environmental influences on the phenotypesand the associations among them were determined. The sample consisted of 746 monozygotic (MZ) and 770dizygotic (DZ) twins in the age group of 50-65 (mean = 57.11 years, SD = 4.5). The results showed that asingle factor accounted for about 50% of the overall variance in MS symptom reporting. Two neuroticismfacets, N1: anxiety and N3: depression, appeared as significant in the regression analyses. Both these facetsand MS symptoms were strongly influenced by genetic factors [heritability (h2) = 0.46-0.54]. While there wasa considerable overlap in genetic risk factors between the three phenotypes, a large proportion (71%) of thegenetic variance in MS symptoms was unique to the phenotype, and not shared with the neuroticism facets.