Psychiatric morbidity and social functioning among adults with borderline intelligence living in private households.
Adults with borderline IQ carry high rates of anxiety, drug, and personality disorders yet rarely receive talk therapy—so screen and refer.
01Research in Context
What this study did
Porter et al. (2008) asked 1,301 UK adults with borderline IQ to fill out mental-health and social-life surveys.
They compared answers to adults with average IQ living in the same neighborhoods.
Doctors also recorded who took pills and who got talk therapy.
What they found
The borderline-IQ group had twice the rate of anxiety, drug, and personality disorders.
They were poorer, lonelier, and took more meds yet saw fewer therapists.
In short, treatable problems were high but therapy use was low.
How this fits with other research
Matson et al. (2009) show the same adults have tiny social circles and little paid work.
Versluis et al. (2025) prove the group can still gain from therapy: two weeks of intensive EMDR wiped out PTSD in most clients.
Jackson et al. (2025) add that personality-trait levels in borderline-IQ adults match those with mild ID.
Together the papers say: problems are common, but skills and therapy can still help.
Why it matters
If you serve adults with mild or borderline ID, add quick mood and drug-use screens to every intake.
Use plain-language questions and picture aids.
When scores are high, refer to CBT, EMDR, or social-skills groups instead of only prescribing pills.
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02At a glance
03Original abstract
BACKGROUND: Approximately one-eighth of the population will have DSM-IV borderline intelligence. Various mental disorders and social disability are associated with it. METHOD: The paper uses data (secondary analysis) from a UK-wide cross-sectional survey of 8450 adults living in private households. Data were collected on psychiatric disorders, intellectual level, social functioning and service use. RESULTS: In total, 12.3% of the sample had borderline intelligence. The prevalence of psychotic disorder was not significantly increased, but the group showed significant social disadvantage and increased rates of neurotic disorders, substance misuse and personality disorders when compared with their counterparts of normal intelligence. The borderline group was more likely to receive psychiatric medication, but not talking therapies. They appear to use significantly more services, including emergency services. CONCLUSION: Adults with borderline intelligence are more likely to suffer from treatable mental disorders and an excess of substance misuse. Services should be aware of hidden morbidity in this group.
Journal of intellectual disability research : JIDR, 2008 · doi:10.1111/j.1365-2788.2007.01001.x