What is the meaning of associations between personality traits and anxiety and depressive disorders?

Qual é o significado das associações entre as características da personalidade e os distúrbios de ansiedade e depressivo? In this issue, Freire et al. present data on personality traits in patients with acute panic disorder, major depressive disorder, or both conditions, as well as controls. The mean neuroticism scores in each of the 3 patient groups were higher than that of the control group, and comorbidity was associated with particularly high neuroticism. In addition, the mean extraversion scores were lower in 2 of the 3 patient groups than that of the control group, and comorbidity was associated with particularly low extraversion [notably, though, the controls here were younger than the patients, and there was a statistically significant relationship between extraversion and age (older subjects were less extraverted)]. The authors construe their results in terms of a spectrum of difficulties with common personality attributes. Freire et al. highlight an important area of research that has implications for clinical practice and prevention. However, it is quite difficult to accept a simple overarching explanation for results like those presented by Freire et al. As noted by the authors, there are multiple ways in which personality traits seem to relate to anxiety and depressive disorders. For example, there are a growing number of longitudinal studies that suggest that high neuroticism is a “risk factor” for a variety of anxiety and depressive disorders, in that neuroticism at baseline predicts subsequent first onset of these psychiatric conditions. Secondly, a number of studies suggest that acute states of anxiety or depression affect the measurement of long-standing personality traits. Thirdly, personality traits and anxiety and depressive disorders may be influenced by the same genetic and environmental risk factors. A study by Kendler et al. stands out as an exemplar of causal research on personality traits and Axis I conditions. These authors found that 1) baseline neuroticism predicted onset of major depression over the following year (neuroticism appeared to be a “risk factor”); 2) neuroticism increased substantially in subjects who were acutely depressed at follow-up (there appeared to be “state” effects of depression on neuroticism measures); and 3) neuroticism was also increased in subjects who had developed depression but were not acutely ill at follow-up (there appeared to be at least short-term “scar” effects of recent depression on neuroticism measures). Further, the subjects in this study were twins, and the authors found evidence of genetic overlap between neuroticism and major depression (i.e., some of the same genetic factors appeared to affect both neuroticism and major depression – consistent with the genetic spectrum concept). Finally, Kendler et al. were able to address an interesting question: “Does neuroticism represent an inherited ‘true’ risk factor for major depression (a true causal factor), or does neuroticism merely reflect an inherited vulnerability to major depression? ” Modelfitting results suggested that that the latter was the case; i.e., high neuroticism appears to be a sort of marker for genetic vulnerability to depression. This finding is somewhat at odds with most people’s understanding of neuroticism as a true vulnerability factor. Unfortunately, the relationships between personality traits and anxiety disorders have not been studied nearly as systematically. Nevertheless, the current literature suggests that 1) high neuroticism predicts later onset of anxiety disorders, 2) current panic may confound personality measurements, and 3) high neuroticism (and, in some Editorial 3