People with borderline intellectual functioning (BIF) have a number of problems in life, including neurocognitive, social and mental health problems. They typically have lower-skilled jobs and earn less money.

People with borderline intellectual functioning (BIF) have an IQ test that is one to two standard deviations below average (i.e. 70 – 85). The adaptive behaviour of people falling in this group needs to be taken into account. People with BIF are typically not eligible to receive intellectual disability-related support.

When it comes to determining support (e.g. special education or not) it is often assumed that there is a discrepancy between performance in academic skills and the general level of intelligence.

//NEUROCOGNITIVE FUNCTIONING

--Academic and cognitive skills

Children with borderline intellectual functioning were outperformed by peers of the same age with average intelligence on measures of memory skills. There appears to be a deficit in memory functions in people with borderline intellectual functioning. Children with BIF show structural abnormalities in the phonological store. Furthermore, there appear to be developmental lags in their visuospatial and central executive subsystems. In short, the working memory functions of children with BIF seem to develop in line with their general intellectual abilities as they are experiencing a developmental lag and not a qualitative deviation from normal development.

Children with BIF showed poorer attention shifting (1), cognitive inhibition (2), problem solving (3), planning (4) and response inhibition (5) than controls. Processing speed in children with BIF appears to be slower. However, impulse control appears to be the same as the controls. Arithmetic skills for children with BIF were poorer than for the controls. There is no consensus regarding reading and writing skills.

Students with BIF used theories that were more immature than peers of average intelligence. They prefer to use intentional mechanisms as a relevant causal explanation (e.g. I want my child to have blue eyes so my child will have blue eyes). Furthermore, they used less advanced learning strategies than other children.

--Motor skills

About 40% of the children with BIF showed no motor problems while 43% showed definitive motor problems. This indicates that BIF is associated with motor problems. People with BIF showed better motor and memory functioning than people with mild intellectual disability. However, people with a specific learning disorder mostly outperformed the BIF group or had equal performance on measures. Executive functioning appeared to be poorer among the BIF group than the mild intellectual disability and specific learning disability group.

//SOCIAL BEHAVIOUR

--Social interaction
There is more solitary play and less group-play behaviour among children with borderline intellectual functioning compared to controls. Peers appear to have a great impact on behaviour as there was more positive interaction when children with BIF were paired with average-intelligence same-age children than when they were paired with other children with BIF.

Mothers of children with BIF exhibited less positive and less sensitive parenting than mothers of children with average or far below average IQ. It is likely that the parental understanding of the problems of children with BIF is inadequate. Children with BIF had more passive and aggressive and fewer assertive responses in social situations. Children with BIF recognized all facial expressions more often than peers of lower IQ but less often than peers of average IQ.

--Antisocial behaviour

People with BIF appear to be overrepresented in populations of criminal offenders. Antisocial behaviour was shown more often by boys with BIF but not girls.

//MENTAL HEALTH

Mental health problems were more common in people with BIF than the general population. Children with intellectual disability had more hyperactivity and peer problems than children with BIF but also showed more prosocial behaviour. Individuals with BIF are less likely to receive treatment for mental health. When they receive treatment, they are more likely to be treated with medication than counselling.

//EMPLOYMENT AND MARRIAGE

Occupational prestige and income were lower for individuals with BIF. More women with BIF were unemployed or housewives than in the general population and adolescents with BIF had difficulty maintaining a job.

--Marriage

The rate of marriage was lower among people with BIF than controls at age 35 but not at age 50.

//RISK AND PREVENTIVE FACTORS

The risk of BIF increased with low birth weight (1), poor family environment (2), a low level education of the mother (3), exposure to toxic metals (4), maternal drug use during pregnancy (5), familial history of intellectual disability (6) and mother’s illiteracy (7). Developmental delays are connected to BIF. The risk factors associated with BIF may not be specific to BIF but general risk factors.

Education (1), social contacts (2) and personal qualities (3) were protective factors for BIF. The social contacts include supportive parenting, role models for achievement and warm relationships. Personal qualities include flexibility to change with situational demands, childhood competence, perseverance and relationship skills.

Early training and training with adolescents’ communication skills appear to be effective in the ‘treatment’ of BIF.

It is possible that the transition from adolescence to adulthood is problematic for people with BIF.