Personality Trait Profiles in People With Mild Intellectual Disability: A Comparative Study.

Background: Personality assessment in people with mild intellectual disability (MID) is difficult due to their communication difficulties and lack of reliable instruments. In addition, characteristics of maladaptive personality traits may be attributed to the intellectual disability. As a result, little is known about (maladaptive) personality traits in people with MID. The aim of this study was to explore maladaptive personality traits of people with MID and compare them to those of two comparison groups.

Methods: Maladaptive personality traits of people with MID referred to specialised mental health care (n = 75) were compared with those of people with borderline intellectual functioning referred to specialised mental health care (BIF, n = 69) and those of people with average educational levels from general mental health care (AVE, n = 73) using the Dimensional Assessment of Personality Pathology-Short Form.

Results: People with MID scored higher on Affective Lability, Anxiousness, Identity Problems, Insecure Attachment and Suspiciousness and lower on Narcissism and Social Avoidance compared to the people with AVE. No differences in personality trait scores were found between people with MID and people with BIF, except for a lower score on Social Avoidance in those with MID. Almost all differences demonstrated small effect sizes.

Discussion: Maladaptive personality traits of people with MID and comorbid psychopathology are of similar severity compared to those of people with BIF and comorbid psychopathology or people in mental health care with average educational levels. This study emphasises that clinicians look beyond the intellectual and adaptive disabilities when assessing for mental health problems in people with MID, while meeting their needs when it comes to the treatment of these problems.