The role of neuroticism in self-harm and suicidal ideation: results from two UK population-based cohorts

Social Psychiatry and Psychiatric Epidemiology https://doi.org/10.1007/s00127-019-01725-7 ORIGINAL PAPER The role of neuroticism in self‑harm and suicidal ideation: results from two UK population‑based cohorts Jonathan D. Hafferty1 · L. B. Navrady1 · M. J. Adams1 · D. M. Howard1 · A. I. Campbell2 · H. C. Whalley1 · S. M. Lawrie1 · K. K. Nicodemus2 · D. J. Porteous2,3 · I. J. Deary3 · A. M. McIntosh1,3 Received: 30 July 2018 / Accepted: 13 May 2019 © The Author(s) 2019 Abstract Background Self-harm is common, debilitating and associated with completed suicide and increased all-cause mortality, but there is uncertainty about its causal risk factors, limiting risk assessment and effective management. Neuroticism is a stable personality trait associated with self-harm and suicidal ideation, and correlated with coping styles, but its value as an independent predictor of these outcomes is disputed. Methods Prior history of hospital-treated self-harm was obtained by record-linkage to administrative health data in Generation Scotland:Scottish Family Health Study (N = 15,798; self-harm cases = 339) and by a self-report variable in UK Biobank (N = 35,227; self-harm cases = 772). Neuroticism in both cohorts was measured using the Eysenck Personality QuestionnaireShort Form. Associations of neuroticism with self-harm were tested using multivariable regression following adjustment for age, sex, cognitive ability, educational attainment, socioeconomic deprivation, and relationship status. A subset of GS:SFHS was followed-up with suicidal ideation elicited by self-report (n = 3342, suicidal ideation cases = 158) and coping styles measured by the Coping Inventory for Stressful Situations. The relationship of neuroticism to suicidal ideation, and the role of coping style, was then investigated using multivariable logistic regression. Results Neuroticism was positively associated with hospital-associated self-harm in GS:SFHS (per EPQ-SF unit odds ratio 1.2 95% credible interval 1.1–1.2, pFDR 0.0003) and UKB (per EPQ-SF unit odds ratio 1.1 95% confidence interval 1.1–1.2, pFDR 9.8 × 10−17). Neuroticism, and the neuroticism-correlated coping style, emotion-oriented coping (EoC), were also associated with suicidal ideation in multivariable models. Conclusions Neuroticism is an independent predictor of hospital-treated self-harm risk. Neuroticism and emotion-orientated coping styles are also predictive of suicidal ideation. Keywords Neuroticism · Self-harm · Record-linkage · Coping · Ideation Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00127-019-01725-7) contains supplementary material, which is available to authorized users. * Jonathan D. Hafferty 1 Division of Psychiatry, Kennedy Tower, Royal Edinburgh Hospital, University of Edinburgh, Edinburgh EH10 5HF, UK 2 Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, Western General Hospital, University of Edinburgh, Edinburgh, UK 3 Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK Suicide is a major global health challenge and is the leading cause of death among young people aged 20–34 years in the UK [69]. A variety of sociodemographic, biological and psychological risk factors have been proposed for completed suicide (for review, see [89]). Among the most predictive, and potentially amenable to clinical intervention, are (1) history of self-harm, which is associated with 37.2 times increased risk of completed suicide within the first year following an act of self-harm [70], and (2) suicidal ideation, which in a recent meta-analysis is associated with increased risk ratios for competed suicide of 2.35–8.00 [48]. Self-harm is a common and debilitating behaviour characterised by self-injury or self-poisoning, irrespective of the 13 Vol.:(0123456789) Social Psychiatry and Psychiatric Epidemiology apparent purpose of the act [63]. Estimated lifetime prevalence of self-harm is 1–6%, with the UK reportedly having the highest self-harm rate in Europe [46]. Incidence is estimated at 400/100,000 population per year [90]. However, many people who self-harm do not attend clinical services, and thus true prevalence may be considerably greater [43]. Self-harm is aetiologically associated with childhood maltreatment [32, 84] and physical illness [23]. In addition, a number of demographic factors are predictive of self-harm, including being female [76]; young adulthood [76]; being unmarried [76]; or separated/divorced [72]; being socioeconomically disadvantaged [88]; unemployed [74]; or low educational attainment [75]. Psychiatric illness also has well-known associations with self-harm [79]. One systematic review of non-fatal self-injury presenting to hospital reported a pooled prevalence for psychiatric disorder of 83.9%, with mood disorders the most common category (58.5%) [44]. The association between depressive disorder and self-harm has been found in numerous other studies [6, 16]. Self-harm is performed with a variety of motivations, including attempted suicide, self-mutilation, seeking psychological relief, and the communication of distress. Often, there is not a single readily definable motivation, but multiple factors occurring simultaneously [20]. In the majority of cases, the intention is not to die [79]. Given the difficulties encountered clinically in ascertaining intent and motivation, it has been argued that the terms ‘deliberate self-harm’, ‘selfharm’, ‘attempted suicide’ and ‘suicidality’ are imprecise for research purposes [67]. Recently, the Fifth Edition of the Diagnostic and Statistical Manual for Mental Disorders [2] has proposed a distinction between ‘nonsuicidal self-injury’ (NSSI) and ‘suicidal behaviour disorder’ as ‘Conditions For Further Study’. However, it remains controversial whether such discrete categorizations can be confidently made in clinical practise, or demonstrate differentiable suicidal outcomes, given the biases inherent in self-report, and the close association of NSSI with suicidal behaviour [19, 52]. Broadly defined ‘self-harm’, therefore, retains an important clinical outcome in current suicidology literature [42, 52]. Another approach to subcategorising self-harm is on the basis of whether it has received hospital treatment. Hospitaltreated self-harm is recognised as an important intervention point in suicide prevention [12]. Approximately oneseventh to one-fifth of those with hospital-treated self-harm will repeat their self-harm within 1 year [71]. Self-harm that requires medical attention significantly increases the future risk of suicide [19], particularly if admission to hospital is required [37]. Within the UK, up to one-fifth of those who die by suicide have attended hospital for self-harm in the preceding year [34]. Suicidal ideation, additionally, is an important antecedent to progression to significant self-harm and suicide attempts 13 (...truncated)