Diverse diagnostic and behavioural patterns amongst people with a dual diagnosis.
Dual-diagnosis clients fall into six behavior clusters, so tailor plans to the cluster, not the umbrella label.
01Research in Context
What this study did
McConkey et al. (1999) ran a factor analysis on 940 people with dual diagnosis. They wanted to see if everyone looked the same or if smaller groups appeared.
The team used behavior ratings already in the files. No new tests were given.
What they found
Six clear behavior clusters showed up. One group was mostly calm, another showed self-injury, a third had mood swings, and so on.
The big take-away: dual diagnosis is not one big blob. Services need to treat the cluster, not just the label.
How this fits with other research
Soenen et al. (2009) did the same math on 73 adults with mild ID and also found four behavior clusters. This backs up the 1999 finding with a smaller, stricter sample.
Shuster et al. (2014) looked at 36 ASD factor studies and saw only two stable domains: social-communication and restricted-repetitive. That sounds like a contradiction, but Jill focused only on autism. When ASD is mixed with ID and other risks, more clusters pop out.
Garrison et al. (2025) later found five stable mood-risk profiles in youth with ID. They extended the idea: once you split by behavior, the groups stay stable for at least a year.
Why it matters
Stop writing generic behavior plans for dual diagnosis. Screen for the six clusters first, then pick interventions that match each profile. You will waste fewer hours on plans that never fit.
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02At a glance
03Original abstract
People who have both an intellectual disability and a mental illness diagnosis are gaining more attention in the mental health and developmental disabilities service systems. This interest is partly because of the challenging behaviours and the complexities of the problems in this population. The present study analyses the diagnoses, behaviour problems and demographic characteristics of a group of people with a dual diagnosis to determine if specific patterns are evident which distinguish this set of subjects. A group of 940 people who were part of a class action lawsuit in North Carolina, USA, were investigated. A factor analysis was conducted to determine whether or not distinct patterns or factors were evident. This analysis revealed six distinct patterns primarily based on the behaviour problems of this group and secondarily based on their diagnoses. These six factors are referred to as: (1) aggressive/disturbing behaviour; (2) withdrawal/asocial behaviour; (3) inappropriate behaviours; (4) sociopathic characteristics; (5) suicidal or runaway crises; and (6) pica disorder. The findings suggest that mental illness is a prominent characteristic of some of the six factors but not of others. Furthermore, an intellectual disability diagnosis and the particular level of intellectual disability are reflected very differently amongst all of these factors.
Journal of intellectual disability research : JIDR, 1999 · doi:10.1046/j.1365-2788.1999.00188.x