Olanzapine for chronic, stereotypic self-injurious behaviour: a pilot study in seven adults with intellectual disability

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Abstract
Dopamine one (D1) receptor supersensitvity in the corpus striatum is said to be the primary mechanism within the dopamine model proposed for chronic, refractory self-injurious behaviour (SIB), which may explain why conventional neuroleptics have proven largely ineffective. In common with other atypical antipsychotic agents, olanzapine has more affinity for the D1 receptor. The present study explored whether olanzapine could reduce rates of the stereotypic form of chronic SIB, a subtype where dopamine dysfunction is the most likely underlying mechanism. A clinical sample of seven patients with various levels of learning disability who displayed features of stereotypic SIB were assessed over a 6-week period of baseline measurement and a 15-week treatment phase during which olanzapine was added to existing medication. Both SIB and other aberrant behaviours were measured by daily nurse rating and the Self-Injury Trauma Scale (SITS). All measurements were unblind. Doses ranged from 5 to 15 mg. Out of the seven subjects, three showed a clear improvement, one showed a marginal improvement, one deteriorated, and the data was equivocal for the remaining two individuals. The means of the SITS Number and Severity Indices (NI and SI, respectively) reduced significantly from baseline during both the 5- and 10-mg treatment phases, and taking treatment as a whole, by 53% and 48%, respectively (NI: mean = 0.7 units reduction, P = 0.02; SI: mean = 0.9 units reduction, P = 0.04). The risk index also reduced, but did not reach significance. A modest reduction in mean nurse-rated SIB was not significant for either phase or for treatment as a whole. At doses above 5mg, mean scores deteriorated on balance, although two responders showed a marginal additional improvement. Olanzapine was well tolerated with one adverse event reported (somnolence) which was mild and transient. The present pilot study suggests that olanzapine can reduce stereotypic SIB. A larger trial is indicated.