This study set out to look at associations between psychiatric disorders in people with learning disabilities and challenging behaviours. The study used a large sample and controlled for sex, age, autism and degree of learning disability.

The researchers used data from 47% of all people with learning disabilities who were known to and receiving services from agencies in New York State. Senior psychologists in 14 agencies completed the Institute for Basic Research – Modified Overt Aggression Scale (IBR-MOAS) using information kept on the files of the people in the sample. Analysis was subsequently carried out on data from 4,069 participants.

The researchers found from this analysis of case notes that impulse control disorder and bipolar disorder were strongly associated the five domains of aggressive behaviour in the IBR-MOAS.

Psychotic disorder was highly associated with four of the domains, all except physical aggression against self.

They found anxiety was most associated with physical aggression against self and verbal aggression against self.

Depression was associated with verbal aggression against self.

Obsessive compulsive disorder was associated with physical aggression against objects and personality disorders were associated with verbal aggression against others, verbal aggression against self and physical aggression against self.

They found autism to be associated with physical aggression against others against objects and against self.

Mild to moderate learning disability was associated with verbal aggression against others and against self and severe to profound learning disability was associated with physical aggression against objects and against self.

Being female was found to be most associated with verbal aggression against self.

The authors suggest that psychosis and depression were over-diagnosed in persons with mild to moderate learning disabilities although under-diagnosed in those with severe and profound learning disabilities. They also suggest that the pattern of associations suggested by the study could be helpful indicators for those involved in the treatment of challenging behaviours in people with learning disabilities.

Association of aggressive behaviours with psychiatric disorders, age, sex and degree of intellectual disability: a large-scale survey, Tsiouris, J et al, in Journal of Intellectual Disability Research, 55: 636–649