Background: Research on affective disorders in adults with intellectual disability (ID) suggests that depression may not present a 'classic picture' in individuals with severe and profound ID, but may include challenging behaviours, which are referred to as 'atypical symptoms', such as self-injury, aggression and irritability. The aim of the present study was to explore whether there is an association between constructs relating closely to the core symptoms of depression and challenging behaviours in adults with severe and profound ID.
Method: Mood and levels of interest and pleasure were measured in 53 adults with severe or pro-found ID using the Mood, Interest and Pleasure Questionnaire (MIPQ).
Results: Two groups of adults were identified based on MIPQ scores: (1) a 'low mood' group (lowest score = 12); and (2) a comparison group (highest scoring = 12). The groups were clearly differentiated on the MIPQ (P < 0.0001), but were comparable on age, gender and medication use. The Challenging Behaviour Interview showed no difference between the two groups in self-injury, aggression or disrupting the environment. A secondary analysis revealed that participants who showed challenging behaviour scored significantly lower on the MIPQ than those who did not show challenging behaviour.
Conclusions: Possible reasons for these results and considerations for future studies are discussed.