New paper reveals multiple factors behind neurodevelopmental disorders

Paper examines multiple factors affecting atypical development and efficacy of interventions

Scientists from Birkbeck’s Centre for Brain and Cognitive Development have published a new paper in the journal Clinical Psychological Science. The paper examines the importance of multiple methodologies when investigating neurodevelopmental disorders, such as autism. It also paid close attention to the importance of timing when delivering interventions.

The paper was led by Professor Annette Karmiloff-Smith and combined the results of four separate studies to show why treating neurodevelopmental conditions with a narrow range of interventions may not be effective at ameliorating symptoms. The studies considered both environmental and genetic risk factors; and how the two might interplay to determine how an individual responds to an intervention.

The effects of socio-economic status on early brain development

In the first study the scientists examined the brains of six-nine month old infants from families with low socio-economic status. They found that disparities in socio-economic status are strongly associated with differences in the activity of neural structures in the brain which support language and attention abilities. The differences were observed specifically in the frontal area of the brain.

Professor Karmiloff-Smith said: “By focusing on young infants we showed that low socio-economic status in the first months of life is a significant risk factor for future atypical development. This means that timing of any interventions to address this environmental risk factor needs to be during those crucial early months.”

Anxiety disorders in adolescents

The second study conducted by colleagues in the USA aimed to understand why cognitive behavioural therapy (CBT) is effective for some adolescents with anxiety disorders, but does not help others (40-60%). Using mouse models and human neuroimaging to assess genetic factors influencing an individual’s response to CBT, they found a clear genetic difference between those who responded to CBT and those for whom it was not effective.

Professor Karmiloff-Smith explains: “Understanding whether efficacy of the intervention is influenced by genetics or by other factors is vital, as it enables us to know which individuals are likely to be the most responsive to CBT interventions.”

Same behaviour, different causes

The paper also presented research examining the brain activity of individuals with high-functioning autism whose results in memory-based tasks were similar to those of healthy control participants. They showed that although these individuals were able to produce the same results as typical adults at the behavioural level, the underlying brain activity to achieve those results was substantially different.

Regression in autism spectrum disorders

Some toddlers develop typically, in terms of their motor, social, cognitive and language skills, and are then observed to regress during the second year of life. Professor Karmiloff-Smith’s group reported a study using neurocomputational models (artificially created organic neural networks) to demonstrate that larger neural network size is a risk factor for suffering greater impairment to cognitive function during regression and that the earliest symptoms to emerge in autism are likely to be sensory and motor rather than social.

Professor Karmiloff-Smith said: “This paper brought together five different methodologies. We believe that future research into neurodevleopmental disorders will require teams to gather data simultaneously using different methods on the same individuals because, as our studies have shown, there are multiple factors affecting atypical development and efficacy of interventions.

“We need to be able to understand the convergence of behaviour, genetics, neural networks and environment, as well as how timing of interventions affects neurodevelopment.

“These studies have thrown up many future questions but we predict that to achieve maximum efficacy, interventions will need to address multiple areas and that by focussing on single domains we risk missing opportunities to make real impact on the symptoms of individuals with neurodevelopmental conditions.”