Childhood autism : an appeal for an integrative and psychobiological approach
Introduction: Childhood autism, overtly expressed as social indifference and repetitive motor patterns, in fact involves a range of problems covering sensory, attentional, cognitive, emotional, language as well as motor areas of function - 25 symptoms can be listed. Although a reduced verbal IQ and language difficulties are frequent, a major intervening variable may be problems with the development of a "theory-of-mind" ....the ability to comprehend the mental states of others. Prevalence rates per 10,000 of the population range from 2 to 16 in different countries, rising to 50 if one includes spectrum autistic disorder. A number of sometimes related organic associations and potentially separate aetiologies are described. Biology: Evidence for delayed neurotransmission (evoked potentials) and a lack of flexibility in physiological responses (signal detection, cross-modal integration) may underlie the attenuation of monitoring processes that lead to withdrawal and stereotypies. Neuropsychological task performance provides limited and qualified evidence for impaired frontal function, although this could explain event-related potential (ERP) evidence for more of a deficit with controlled attention (Nd) than in automatic processing (MMN). [ERPs also underline the difficulties in generating differential responses to relevant and irrelevant stimuli.] Imaging studies show some structural abnormalities in half the patients (e.g. ventricle volume increases), but indices of activation, though in the normal range do not appear situation-appropriate. Pharmacology: a) A significant proportion of autistic subjects show increased peripheral measures of serotonin and quite often raised dopamine metabolism - that in some high-functioning cases has been claimed to be beneficial. It is plausible that changes in monoaminergic transmission are inadequately compensated by changes in the other transmitter systems. b) With serotonin and dopamine responsible for inhibition/volume-control and for switching/flexibility we propose an imbalance of these systems that results in a stop-go form of neuronal communication that inevitably leads to anomalous responses at the whole organism level. c) At least 20 forms of pharmocotherapy have been attempted, the best with improvement limited to a few patients improving particular symptoms only. The best have proved to be dopamine or opioid antagonists, but at best - these have a limited and modest role to play in clinical care Conclusions: The impairment of children with autism manifests itself at many levels - treatment concepts must attempt to integrate these, with emphasis on the particular abilities and difficulties of the individual. The need is to synthesize the different levels of analysis for a psychobiological approach to be integrated into the wide-ranging remedial programmes currently practised.