Towards an approach to mental disorders based on individual differences

T. Widiger has been one of the most influential scholars exploring the role of personality in psychopathology in the last 20 years. In this paper, he provides the reader with a highly accurate, and at times somewhat provocative, overview of the main findings concerning the interface between personality and psychopathology, lively conveying also the excitement that is permeating research on the role (actually, the roles) of personality in psychopathology. I tried to read the article as a clinician, not as a researcher. From a clinician’s perspective, the complex relationships between personality and psychopathology which are consistently documented by research findings suggest that the time is coming for psychiatry to shift from the aim “to carve nature at its joints” to adopting individual differences in personality as the main perspective to understand mental disorders. Putting personality at the cross-roads of adaptive functioning and mental dis- orders does not imply to dismiss a me- dical approach to diagnosis. Rather, it implies to put the subject’s mental dis- order(s) in the perspective of the “characteristic manner in which she/he thinks, feels, behaves, and relates to others”, quoting Widiger’s words. In turn, this involves considering the subject’s mental disorder(s) in the perspective of his/her developmental history, including psychobiological and psychophysiological aspects and risk factors. Widiger’s accurate presentation of the mutual influences between personality and mental disorders also avoids the pitfalls of a simplistic approach to the treatment of mental disorders. In fact, an approach to mental disorders based on individual differences implies taking into account the subject’s personality when deciding the overall therapeutic strategy. For instance, it is well known that, in people with obsessive-compulsive disorder (OCD), the co-diagnosis of schizotypal personality disorder may negatively affect treatment response 1, which suggests the need for an individual case formulation in OCD patients with complex symptomatology and comorbid Axis II disorders 2. Consistent with the complex interplay between personality and mental disorder that Widiger highlights in his article, recent data suggest that impulsivity is a behavioral endophenotype mediating risk for stimulant dependence that may be exacerbated by chronic drug exposure 3. Thus, taking into account this personality trait could be relevant for both preventing substance abuse and fostering abstinence during the maintenance phase of a treatment program for drug addiction. Neuroticism seems to represent a risk factor for depression as well as for several other mental disorders and personality disorders 4. Interestingly, neuroticism seems to be associated also to genetic risk for depression 5. Moreover, personality disorders are among the significant predictors of the risk that a current depressive episode becomes chronic 6. Cuijpers et al 4 pointed out that the economic costs of neuroticism exceed those of common mental disorders. Thus, they suggested that psychiatry should start thinking about interventions that focus not on each of the specific negative outcomes of neuroticism but rather on the starting point itself 4. Another implication of Widiger’s article is that it is possible to adopt a personality-centered approach to mental disorder without adhering to a specific personality theory. Although a Five Factor Theory of personality actually exists 7, the Big Five model of personality does not represent a particular theoretical perspective but was derived from analyses of the terms people use to describe themselves and others 8. This model actually integrates different theories of personality. Widiger’s paper shows that the Big Five traits – i.e., openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism – may have this integrative role also in psychopathology.