Compared with healthy control patients, people with conversion disorder are more likely to have experienced maltreatment or stressful life events, according to a meta-analysis published in Lancet Psychiatry. The highest risk was associated with emotional neglect, as opposed to the more conventionally highlighted history of physical or sexual abuse.
Conversion disorder (functional neurological disorder) had long been considered a product of internal psychic stress, but that conception has come into question more recently, with clinicians divided on causality. Recent Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, changes removing life stressors as a diagnostic requirement prompted the researchers to explore the association between severe stress and this condition in the face of unclear evidence.
The investigators conducted a systematic review of all relevant case-control studies between 1965 and 2016 by searching PubMed and Science Direct, and identified 34 of low to moderate quality for inclusion, with a total of 1405 patients and 2227 controls. They calculated comparative frequencies and odds ratios (ORs) for various stressors, as well as population attribution fractions, which measure risk factor contributions on a population level by considering prevalence.
In adult and pediatric populations, patients with conversion disorder had higher frequencies of significant stressors than did control patients, with childhood abuse or neglect posing a higher risk than that suffered in adulthood. Emotional neglect in childhood was most common and carried the highest risk (49% for cases vs 20% for controls; OR, 5.6; 95% CI, 2.4-13.1), followed by physical abuse (30% vs 12%; OR, 3.9; 95% CI, 2.2-7.2) and sexual abuse (24% vs 10%; OR, 3.3; 95% CI, 2.2-4.8; P <.0001 for all factors). In adulthood, these same stressors resulted in ORs of 3.2 (95% CI, 1.4-7.2), 2.9 (95% CI, 1.6-5.4), and 2.8 (95% CI, 2.0-3.9), respectively.
After population attribution fraction adjustments, researchers found that physical abuse had the greatest effect on development of conversion disorder (16.9% in childhood and 14.6% in adulthood), followed by emotional neglect and sexual abuse. Importantly, however, 13 studies showed a significant proportion of conversion disorder patients reporting no major stressors before diagnosis, and there was substantial heterogeneity among the studies considered (I2, 21.1%-90.7%).
Study limitations included selective choice of data points, limited quality of included literature, small study sizes with high heterogeneity, frequent use of questionnaires vs interviews, and possible recall bias leading to under- or overreporting.
This comprehensive analysis verified the probable role of severe life stressors in the development of conversion disorder. At the same time, the findings also supported recent Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, changes that removed said stressors as a requirement for diagnosis. The authors acknowledged that although severe stress likely influences the disorder’s progression, it should no longer be a diagnostic prerequisite.
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Ludwig L, Pasman JA, Nicholson T, et al. Stressful life events and maltreatment in conversion (functional neurological) disorder: systematic review and meta-analysis of case-control studies. Lancet Psychiatry. 2018;5(4):307-320.