Background

An intellectual disability is due to a difference in brain development, either before birth or in early childhood. People with intellectual disability can have difficulties learning and understanding new or complex information, such as new skills, rules, or everyday tasks. To help them in their learning journey, many children and adolescents with intellectual disability receive educational assistance.

Why did we do this study?

There are still many unanswered questions regarding intellectual disability. For example, while we know that people with intellectual disability are at a greater risk of certain psychiatric conditions than the general population, we don’t know yet how brain anatomy and brain functioning is linked to the presence of these co-occurring psychiatric conditions. Moreover, while we know that the challenges experienced by people with intellectual disability change throughout their life, we don’t know yet what aspects of the experience in childhood influence abilities in adulthood. With this study, we were trying to answer some of these questions.

What did we do?

We conducted a large scale prospective study, meaning that we recruited a very large group of adolescents with special educational needs and we assessed their development at regular intervals over seven years to have a precise picture of how their grow up. We measured many aspects of their development, including their mental abilities, their skills, their behaviour, but also the way their brain changed over time.

What did we find?

We have found a lot of important information regarding the brain and cognitive development of adolescents with special educational needs. For example, we found that adolescents who go on to develop symptoms suggestive of schizophrenia also show changes in their behaviour, their thinking, and their brain structure before they get these symptoms. We also found that these changes are similar to the changes seen in people at high risk of schizophrenia due to genetic reasons. Importantly, we found that the ability to function in adulthood was not predicted by intellectual abilities, but by the level of difficult behaviours experienced in adolescence. This suggest that while intellectual abilities influence the development of the brain and the mind, it is the behaviour of the adolescent that can inform of their future outcomes.

Outputs

Our findings have been published in several peer-reviewed journals. You can read some of the publications related to this study by clicking on the links below:

Determinants of adult functional outcome in adolescents receiving special educational assistance. McGeown HR, Johnstone EC, McKirdy J, Owens DC, Stanfield AC. J Intellect Disabil Res. 2013; 57(8):766-773

Amygdala volume in a population with special educational needs at high risk of schizophrenia. Welch KA, Stanfield AC, Moorhead TW, Haga K, Owens DC, Lawrie SM, Johnstone EC. Psychol Med. 2010; 40(6):945-54.

Progressive temporal lobe grey matter loss in adolescents with schizotypal traits and mild intellectual impairment.  Moorhead TW, Stanfield AC, Spencer M, Hall J, McIntosh A, Owens DC, Lawrie S, Johnstone EC. Psychiatry Res. 2009; 174(2):105-9.

Obstetric complications and mild to moderate intellectual disability. Sussmann JE, McIntosh AM, Lawrie SM, Johnstone EC. Br J Psychiatry. 2009 Mar;194(3):224-8.

Increased right prefrontal cortical folding in adolescents at risk of schizophrenia for cognitive reasons. Stanfield AC, Moorhead TW, Harris JM, Owens DG, Lawrie SM, Johnstone EC. Biol Psychiatry. 2008; 63(1):80-5.

Low birthweight and preterm birth in young people with special educational needs: a magnetic resonance imaging analysis. Spencer MD, Moorhead TW, Gibson RJ, McIntosh AM, Sussmann JE, Owens DG, Lawrie SM, Johnstone EC. BMC Med. 2008 Jan 30;6:1. doi: 10.1186/1741-7015-6-1.

Autistic traits and cognitive performance in young people with mild intellectual impairment. Harris JM, Best CS, Moffat VJ, Spencer MD, Philip RC, Power MJ, Johnstone EC. J Autism Dev Disord. 2008 Aug;38(7):1241-9.

The boundaries of the cognitive phenotype of autism: theory of mind, central coherence and ambiguous figure perception in young people with autistic traits. Best CS, Moffat VJ, Power MJ, Owens DG, Johnstone EC. J Autism Dev Disord. 2008 May;38(5):840-7.

Grey matter correlates of early psychotic symptoms in adolescents at enhanced risk of psychosis: a voxel-based study. Spencer MD, Moorhead TW, McIntosh AM, Stanfield AC, Muir WJ, Hoare P, Owens DG, Lawrie SM, Johnstone EC. Neuroimage. 2007 Apr 15;35(3):1181-91.

Schizotypal cognitions as a predictor of psychopathology in adolescents with mild intellectual impairment. Johnstone EC, Owens DG, Hoare P, Gaur S, Spencer MD, Harris J, Stanfield AC, Moffat V, Brearley N, Miller P, Lawrie SM, Muir WJ. Br J Psychiatry. 2007; 191:484-92.

Structural correlates of intellectual impairment and autistic features in adolescents. Spencer MD, Moorhead TW, Lymer GK, Job DE, Muir WJ, Hoare P, Owens DG, Lawrie SM, Johnstone EC. Neuroimage. 2006 Dec;33(4):1136-44.

Who conducted and funded the project?

The project was conducted by Eve Johnstone, David Owens, Stephen Lawrie, and Andrew Stanfield among others.  It was funded by the UK Medical Research Council.