Consideration of the relevance of ethological animal models for human repetitive behavioral spectrum disorders.

This research study investigates the behavior of a horse with a repetitive and seemingly purposeless behavior similar to human compulsive disorders. The study tests the effects of several distinct drugs on this horse’s behavior, revealing that varied drug treatments can have differing levels of success, raising questions about the complexity of neurochemical explanations for behavioral disturbances.

Research Methodology

• The researchers studied a horse that exhibited a form of anomalous behavior called ‘weaving’- a repetitive and seemingly pointless action. This was considered analogous to certain human disorders characterized by similar compulsive behaviors.
• The horse was selectively treated with three different types of drugs which influence different neurotransmitter systems in the brain – a serotonin transport inhibitor (SRI), an opiate antagonist (OA), and a neuroleptic (DA). Each drug treatment was administered over a month-long period, followed by a washout period of one month.
• The horse’s behavior was recorded weekly using videotape, which was then analyzed by two independent evaluators. The frequency of ‘weaving’, the time taken to initiate the weaving behavior, and the severity of the weaving were all noted and recorded.

Results and Findings

• The findings from the drug treatments varied substantially. The serotonin transport inhibitor (SRI) helped reduce the horse’s symptoms by more than 95%. On the other hand, DA and OA resulted in only 40% and 30% reduction in symptoms respectively.
• The substantial variation in the results from the three drug treatments indicates that the neurochemical explanations for disturbances in behavior may be more complex than previously considered.

Implications and Conclusions

• From these findings, the researchers concluded that the currently prevalent approach of explaining disturbances based on single drug vs. placebo trials may oversimplify the complexities of the neurochemical systems.
• Multiple-system investigations probing more than one biological system may be needed to fully understand the complexities of such behavioral disorders.
• This also shows the relevance and potential importance of ethological animal models in advancing our understanding of human psychiatric disorders.