Borderline intellectual functioning: a systematic literature review.
Borderline IQ brings real-life struggles that our field keeps ignoring.
01Research in Context
What this study did
Peltopuro et al. (2014) hunted for every paper on borderline intellectual functioning. They found 49 studies written between 1986 and 2013.
The team pulled out data on thinking skills, mental health, jobs, money, and service use. Most studies were small and used different tests.
What they found
Adults with borderline IQ (70-85) show clear problems. They have weaker memory, poorer social skills, and more mood disorders.
They also earn less money and get fired more often. Yet scientists rarely study this group.
How this fits with other research
Milane et al. (2025) widened the search and found 138 papers. Their 2025 map now replaces the 2014 map as the go-to guide.
Orío-Aparicio et al. (2025) zoomed in on the gap Minna flagged. They show adults with borderline IQ have daily-living skill deficits that match people with mild ID.
Heald et al. (2020) used whole-country records. Their numbers back Minna’s story: psychiatric hospital visits are 3.4 times higher and disability pensions 2.7 times higher for this group.
Why it matters
Your caseload probably includes clients with IQ 70-85 who do not qualify for ID services. Add an adaptive scale like the ABAS-3 to show daily-skill gaps. Use the data to argue for extra time, visual aids, or mental-health referrals. These small tweaks can keep clients employed and out of crisis.
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02At a glance
03Original abstract
The literature related to people with borderline intellectual functioning (BIF) was systematically reviewed in order to summarize the present knowledge. Database searches yielded 1,726 citations, and 49 studies were included in the review. People with BIF face a variety of hardships in life, including neurocognitive, social, and mental health problems. When adults with BIF were compared with the general population, they held lower-skilled jobs and earned less money. Although some risk factors (e.g., low birth weight) and preventive factors (e.g., education) were reported, they were not specific to BIF. The review finds that, despite the obvious everyday problems, BIF is almost invisible in the field of research. More research, societal discussion, and flexible support systems are needed.
Intellectual and developmental disabilities, 2014 · doi:10.1352/1934-9556-52.6.419