Seminar 3 –
Summary and Discussion
Our first discussion focussed on the terminology we should use with respect to co-morbidity. Suggestions included co-occurrence and co-existence as possibilities with colleagues not favouring the term association. Detailed analysis of the terms revealed different preferences within the group but all related back to the formal definition with the core being motor behaviour and other difficulties noted as additional. There was a slight preference for the term ‘co-occurring’.
Amanda Kirby noted that in the end this is always a clinical decision examining the profile of the child. This in turn moved to aetiological considerations and how influential, necessary and indeed helpful this would prove to be. The group did not show consensus on this but the general feeling was that the information could be of use and as better information was provided its usefulness would increase in the future. The group was divided on whether long lists of historical notes were useful.
Overlapping symptoms and history
This concept of overlapping symptoms was taken up by Dido Green and discussion centred on which symptom to address when they were overlapping; again clinical judgement appeared to be favoured although formal assessment was a contributing factor in identifying priorities. Discussion moved to providing a better history of the child in the context of the family with debate on how much medical information was available and necessary. Overall development was taken as another theme with some children showing distinct changes in the profiles they present over time and a discussion on the dynamic nature of this change and the variables (constraints) that may influence this change in profile. The concept of MBD (and derivatives-ABD) was touched upon but it received little positive support as being a useful concept. Many of the group rejected it outright.
Elisabeth Hill examined heterogeneity in children with DCD noting overlap with other conditions such as ADHD. The question of how these different symptoms/conditions exist in the same individual; are they all part of the same condition or are they a number of separate symptoms? Statistical techniques such as cluster and factor analysis but we do yet have the cohort of studies that exist in other developmental disorders such as dyslexia and ADHD. The concept of Atypical Brain Development was again debated with questions asked about what we gain from it. A useful debate ensued with a short presentation of a model by John Morton in his recent book ‘Understanding Developmental Disorders’ in which he distinguishes between the various levels of analysis noting we can do this at the biological/brain level, cognitive level, and behavioural level and we need to be clear of which one we are using when making comparisons.
Mark Mon Williams gave us an account of experimental work that may help to explain some of the characteristics of children with DCD. Specifically he gave an elegant account of work on aiming movements examining Fitts’ Law which involves an explanation of the relationship between the difficulty of a movement, as defined by the width of a target and the distance to travel, and the speed of the movement. Discussions surrounded whether DCD children operate in the same manner and whether Fitts’ Law operates in more complex movements.
Discussion also took place on why children with DCD have these problems and the concept of noise within the system was proposed with engineering analogies used to show that noise, in this case neural noise produces chaos in the system through disrupting the various signals possibly in the cerebellum or parietal cortex. This in turn translates into some of the unstable trajectories we may find in studies involving reaching and grasping in children with CP for example.