Among adults with ADHD, 50–75% have comorbid psychiatric disorders, of which personality disorders (PDs) are among the most common, with several studies reporting a prevalence of between 10% and 75%. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5TM) describes PD as being characterised by inflexibility and pervasiveness, presenting during adolescence or early adulthood and remaining stable thereafter, and causing functional impairment or clinically significant distress. This study aimed to assess the prevalence of personality traits and disorders among a clinical sample of adults with ADHD, and to evaluate the most representative personality profiles in this population.
A consecutive sample of adults (n=107; aged ≥18 years) who accessed the adult ADHD outpatient centre at the AOU San Luigi Gonzaga, Turin, Italy, between January 2015 and May 2017 were screened using the Adult ADHD Self-Report Scale version 1.1 (ASRS-v1.1).* For those adults whose ASRS-v1.1 screen was positive, a diagnosis of ADHD was confirmed via an interview with a trained psychiatrist, using the Diagnostic Interview for ADHD in Adults (DIVA 2.0).† Patients with ADHD were subsequently assessed for PDs by a trained psychologist or psychiatrist using the Millon Clinical Mutiaxial Inventory – 3rd Edition (MCMI-III), which comprises 175 true or false items across 28 scales, including 14 PD scales and 10 clinical syndrome scales,‡ in addition to a validity scale and three modifying indices (disclosure, desirability and debasement), allowing identification of patients who were unwilling or unable to complete the inventory appropriately. MCMI-III scores were standardised, and the base rate (BR) score was used to indicate the probability that an individual had a given personality trait or disorder.§ The prevalence of each identified personality trait and disorder was then estimated, and an exploratory factor analysis (EFA) was conducted to identify personality profiles among the sample.
Of the 107 patients evaluated, 70 were diagnosed with adult ADHD using the Diagnostic and Statistical Manual of Mental Disorders – 4th Edition (DSM-IV) criteria, and were included in the study (mean age, 30.8 [standard deviation 11.53] years; male, 70%). Of these, 30 (42.8%) did not present any PD, while 13 (18.6%) had 1 PD, 13 (18.6%) had 2 PDs, and 14 (20.0%) had ≥3 PDs. The most prevalent personality trait identified was negativistic (n=32; 45.7%), followed by depressive (n=21; 30.0%) and antisocial and sadistic (both n=19; 27.1%). Of the severe PDs tested for, paranoid and schizotypal showed the same prevalence (both n=13; 18.6%), with no patient showing borderline PD. The most frequently identified moderate PDs were negativistic (n=13; 18.6%), depressive (n=12; 17.1%) and sadistic (n=8; 11.4%).
Assessment of sampling adequacy identified three factors that met the criteria for inclusion in the EFA, enabling the identification of three personality profiles. These were:
- Sadistic–antisocial–negativistic (factor 1 explained 42.2% of the variance and was characterised by a strong positive correlation between the sadistic, antisocial and negativistic scale BR scores).
- Masochistic–depressive–dependent–avoidant (factor 2 explained 17.8% of the variance and was characterised by a positive correlation between BR scores on these 4 scales).
- Antihistrionic–schizoid (factor 3 explained 7.6% of the variance and showed positive correlation with histrionic and negative correlation with schizoid scale BR scores).
There were a number of limitations to this study. Firstly, the study design did not exclude comorbid psychiatric disorders, the presence of which could have affected participants’ BR scores on MCMI-III scales. Additionally, the personality profiles identified here are only preliminary profiles for adult ADHD patients; the sample size was not large enough to perform any additional subanalyses, for example to compare personality profiles between patients with different ADHD subtypes. Finally, these results reflect the prevalence of personality traits and disorders in adult ADHD outpatients only, and the results may not be applicable to other populations with ADHD.
The authors concluded that moderate PDs were highly prevalent in the adult ADHD outpatients, with negativistic and depressive personality traits showing the greatest prevalence. In addition, the authors suggested that the three personality profiles identified appear to depict common personality adjustments seen in adults with ADHD, reflecting the persistence of the core symptoms of ADHD (inattentive and hyperactive-impulsive) into adulthood. The authors proposed that the MCMI-III could be utilised by clinicians to develop a personalised, personality-oriented psychotherapy approach for individual adults with ADHD, in order to improve their adjustment to the disorder.
*The ASRS-v1.1 is an internationally validated, self-administered adult ADHD screening tool, comprising a 6-item checklist surrounding adult ADHD symptoms. Patients are required to indicate the frequency of occurrence of each symptom, with the screen considered positive if ≥4 answers are above the significance cutoff value
†The DIVA 2.0 is a validated, structured interview used to assess for adult ADHD according to the DSM-IV diagnostic criteria. It consists of 18 questions (9 relating to inattentive symptoms and 9 relating to hyperactive-impulsive symptoms). For adult ADHD to be diagnosed, the patient must present ≥6 out of the 9 symptoms in each symptom cluster, or ≥6 symptoms across both clusters, which must cause functional impairment across at least two of the following domains: work/education, relationship/family, social contacts, free time/hobby and self-confidence/self-image
‡The MCMI-III is a self-report personality inventory which allows identification of PDs as diagnostic entities (according to the DSM-IV diagnostic criteria) and additionally provides a dimensional estimation of individual personality traits and the severity of a PD. PD scales in the MCMI-III include 11 moderate personality disorder scales (schizoid, avoidant, depressive, dependent, histrionic, narcissistic, antisocial-sadistic compulsive, negativistic and masochistic) and 3 severe personality disorder scales (schizotypal, borderline and paranoid). Clinical syndrome scales include anxiety, somatoform, bipolar: manic, dysthymia, alcohol dependence, drug dependence, post-traumatic stress disorder, thought disorder, major depression and delusional disorder
§On the moderate PD scales, a BR score of 75–84 indicates the presence of a personality trait, while a BR score ≥85 indicates the presence of a PD; on the severe PD scales, a BR score of >75 indicates the presencen of a PD
Oliva F, Mangiapane C, Nibbio G, et al. MCMI-III personality disorders, traits, and profiles in adult ADHD outpatients. J Atten Disord 2018; Epub ahead of print.