Introduction: More than 21 million people worldwide are affected by schizophrenia, with over 50% not receiving appropriate care. Animal-assisted therapies have become increasingly popular in the treatment of both physical and mental illness, including schizophrenia. However, research has often been criticised as being of low quality, stressing the need for more rigorous methods. We conducted a systematic review of randomised controlled trials to examine the effectiveness of AAT for schizophrenia.
Methodology: We searched PubMed, PsycINFO, CINAHL, EMBASE, The Cochrane Library (trials database), CAB Abstracts, and Web of Science. Hand searches of reference lists and citation tracking were conducted for the final list of studies. Articles were independently screened by two review authors to assess eligibility. Studies were eligible if they were randomised controlled trials that had compared animal-assisted therapy to a control group using any participants with a clinical diagnosis of schizophrenia, including schizophreniform disorder and schizo-affective disorder, regardless of age, gender, setting, or severity and duration of illness. Risk of bias was assessed using the Cochrane tool for assessing risk of bias in randomised clinical trials.
Main Findings: Seven studies were included in the review. Meta-analysis was not possible due to heterogeneity between studies, including marked differences in outcome measures and interventions. Four out of seven studies included symptoms as an outcome measure. One study, out of the four, reported improvements in negative symptoms. One study reported improvements in positive symptoms. The remaining two studies reported no significant differences in symptoms between treatment and control. Two of the three studies that did not assess symptoms reported improvements in social interactions/functioning.
Principal Conclusions and Implications for Field: Findings from the included studies suggest that the use of AAT for schizophrenia shows some potential. However, it is important to note that the heterogeneity between studies and the predominantly small sample sizes make it difficult to draw any firm conclusions. In addition to this, there was largely insufficient information across reports to make a judgement of high/low risk of bias. Higher quality RCTs, and more detailed reporting of trials, are much needed in order to assess the true impact of AAT on schizophrenia.