The predictive value of neuroticism for adverse mental and physical outcomes is well documented in the literature. As a construct, neuroticism itself needs to be further clarified because of its overlap with symptoms characterizing depression and anxiety. The goal of this study was to examine the factor structure of neuroticism, and using factor scores, to predict psychological health 7 years later.
Using the 1984 British Health and Lifestyle Study (HALS), we factor analyzed neuroticism as measured by the Eysenck Personality Inventory Neuroticism subscale (n = 5940). Of these 5940 wave one respondents, the General Health Questionnaire (GHQ) scores (n = 3599) seven years later (1991) were dichotomized and regressed against neuroticism factor scores, baseline GHQ, and physical health variables.
A three-factor solution was found for neuroticism that represented anxiety, mood instability, and low mood. Although these three factors were significantly correlated (r = .446 to .530, p < .0001), mood instability had the highest communality and was the strongest predictor of worse mental health (OR: 1.17, robust se: .06, p < .01) next to baseline GHQ.
The results of the present study confirm those of a previous study that indicated mood instability as a distinct and clinically relevant feature of neuroticism.
Mood disorders are common complex conditions (Becker, 2004) with excessive or inappropriate mood as the salient feature. Definitions of particular mood disorders require a minimum number of symptoms for a minimum duration, e.g. 2 weeks for major depression (American Psychiatric Association, 1994). In contrast, when high moods occur, depression becomes bipolar disorder and when mood fluctuates rapidly, the condition is often considered a personality disorder (American Psychiatric Association, 1994). In fact, the recent literature confirms that high moods are common among patients with depression (Nusslock & Frank, 2011), and mood can shift rapidly between lows and highs (Bowen et al., 2006, Eid and Diener, 1999 and Eysenck and Eysenck, 1969), but this view is not widely accepted.
In a previous paper, we reported that one of three factors of the Eysenck Personality Inventory Neuroticism scale represents “moods going up and down” and that this unstable mood factor (along with factors for anxiety and depression) predicts suicidal thoughts (Bowen, Baetz, Leuschen, & Kalynchuk, 2011). Unstable moods are termed mood instability (MI) defined as ‘‘extreme and frequent fluctuations of mood over time” (Trull et al., 2008). MI has a moderate correlation with trait depression but empirically the concepts are distinct enough to be considered as separate constructs (Eid and Diener, 1999, Murray et al., 2002 and Thompson et al., 2011).
Neuroticism is a robust predictor of a variety of psychiatric syndromes and health outcomes that include anxiety and mood syndromes (Kendler & Jablensky, 2011), substance abuse, personality disorders (Jacobs et al., 2011), adverse events (Kendler, Myers, & Reichborn-Kjennerud, 2011), suicidal thoughts (ten Have et al., 2009) and possibly physical health outcomes (Ormel et al., 2004 and Shipley et al., 2007). However, it is still not clear whether our understanding of the concept of neuroticism or of the relationship between neuroticism and mood symptoms has been advanced by this research, since there are shared symptoms of anxiety and depression between the measures of neuroticism and the outcome syndromes (Kendler and Gardner, 2011, Ormel et al., 2004 and ten Have et al., 2009).
In this study, our hypothesis is that MI is an essential component of neuroticism that will predict future psychological ill health. We used data from the British Health and Lifestyle Survey (HALS) (Shipley et al., 2007) to address limitations of our previous study that were the relatively small sample size (n = 125) from one center, the use of the brief Eysenck Neuroticism Scale and the cross sectional nature of the data ( Bowen et al., 2011).
