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Abstract
Evaluating nine randomized controlled trials involving 305 participants, animal-assisted therapy (AAT) may slightly reduce depressive symptoms in people with dementia.
- Participants receiving AAT may experience a reduction in depressive symptoms, with a mean difference of -2.87, although evidence quality is low.
- Quality of life did not appear to improve significantly with AAT, showing a mean difference of 0.45, indicating moderate certainty in the findings.
- There were no clear differences observed in social functioning, problematic behavior, agitation, activities of daily living, or self-care ability among participants receiving AAT.
- Comparing AAT using live animals to robotic animals revealed mixed effects on social interaction, with longer physical contact but shorter conversation duration in the live animal group.
- AAT using live animals showed no significant differences in behavior or quality of life compared to robotic animals or soft toys, with low-certainty evidence.
Simplified
BACKGROUND: Dementia is a chronic condition which progressively affects memory and other cognitive functions, social behaviour, and ability to carry out daily activities. To date, no treatment is clearly effective in preventing progression of the disease, and most treatments are symptomatic, often aiming to improve people's psychological symptoms or behaviours which are challenging for carers. A range of new therapeutic strategies has been evaluated in research, and the use of trained animals in therapy sessions, termed animal-assisted therapy (AAT), is receiving increasing attention.
OBJECTIVES: To evaluate the efficacy and safety of animal-assisted therapy for people with dementia.
SEARCH METHODS: We searched ALOIS: the Cochrane Dementia and Cognitive Improvement Group's Specialised Register on 5 September 2019. ALOIS contains records of clinical trials identified from monthly searches of major healthcare databases, trial registries, and grey literature sources. We also searched MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost), ISI Web of Science, ClinicalTrials.gov, and the WHO's trial registry portal.
SELECTION CRITERIA: We included randomised controlled trials (RCTs), cluster-randomised trials, and randomised cross-over trials that compared AAT versus no AAT, AAT using live animals versus alternatives such as robots or toys, or AAT versus any other active intervention.
DATA COLLECTION AND ANALYSIS: We extracted data using the standard methods of Cochrane Dementia. Two review authors independently assessed the eligibility and risk of bias of the retrieved records. We expressed our results using mean difference (MD), standardised mean difference (SMD), and risk ratio (RR) with their 95% confidence intervals (CIs) where appropriate.
MAIN RESULTS: We included nine RCTs from 10 reports. All nine studies were conducted in Europe and the US. Six studies were parallel-group, individually randomised RCTs; one was a randomised cross-over trial; and two were cluster-RCTs that were possibly related where randomisation took place at the level of the day care and nursing home. We identified two ongoing trials from trial registries. There were three comparisons: AAT versus no AAT (standard care or various non-animal-related activities), AAT using live animals versus robotic animals, and AAT using live animals versus the use of a soft animal toy. The studies evaluated 305 participants with dementia. One study used horses and the remainder used dogs as the therapy animal. The duration of the intervention ranged from six weeks to six months, and the therapy sessions lasted between 10 and 90 minutes each, with a frequency ranging from one session every two weeks to two sessions per week. There was a wide variety of instruments used to measure the outcomes. All studies were at high risk of performance bias and unclear risk of selection bias. Our certainty about the results for all major outcomes was very low to moderate. Comparing AAT versus no AAT, participants who received AAT may be slightly less depressed after the intervention (MD -2.87, 95% CI -5.24 to -0.50; 2 studies, 83 participants; low-certainty evidence), but they did not appear to have improved quality of life (MD 0.45, 95% CI -1.28 to 2.18; 3 studies, 164 participants; moderate-certainty evidence). There were no clear differences in all other major outcomes, including social functioning (MD -0.40, 95% CI -3.41 to 2.61; 1 study, 58 participants; low-certainty evidence), problematic behaviour (SMD -0.34, 95% CI -0.98 to 0.30; 3 studies, 142 participants; very-low-certainty evidence), agitation (SMD -0.39, 95% CI -0.89 to 0.10; 3 studies, 143 participants; very-low-certainty evidence), activities of daily living (MD 4.65, 95% CI -16.05 to 25.35; 1 study, 37 participants; low-certainty evidence), and self-care ability (MD 2.20, 95% CI -1.23 to 5.63; 1 study, 58 participants; low-certainty evidence). There were no data on adverse events. Comparing AAT using live animals versus robotic animals, one study (68 participants) found mixed effects on social function, with longer duration of physical contact but shorter duration of talking in participants who received AAT using live animals versus robotic animals (median: 93 seconds with live versus 28 seconds with robotic for physical contact; 164 seconds with live versus 206 seconds with robotic for talk directed at a person; 263 seconds with live versus 307 seconds with robotic for talk in total). Another study showed no clear differences between groups in behaviour measured using the Neuropsychiatric Inventory (MD -6.96, 95% CI -14.58 to 0.66; 78 participants; low-certainty evidence) or quality of life (MD -2.42, 95% CI -5.71 to 0.87; 78 participants; low-certainty evidence). There were no data on the other outcomes. Comparing AAT using live animals versus a soft toy cat, one study (64 participants) evaluated only social functioning, in the form of duration of contact and talking. The data were expressed as median and interquartile ranges. Duration of contact was slightly longer in participants in the AAT group and duration of talking slightly longer in those exposed to the toy cat. This was low-certainty evidence.
AUTHORS' CONCLUSIONS: We found low-certainty evidence that AAT may slightly reduce depressive symptoms in people with dementia. We found no clear evidence that AAT affects other outcomes in this population, with our certainty in the evidence ranging from very-low to moderate depending on the outcome. We found no evidence on safety or effects on the animals. Therefore, clear conclusions cannot yet be drawn about the overall benefits and risks of AAT in people with dementia. Further well-conducted RCTs are needed to improve the certainty of the evidence. In view of the difficulty in achieving blinding of participants and personnel in such trials, future RCTs should work on blinding outcome assessors, document allocation methods clearly, and include major patient-important outcomes such as affect, emotional and social functioning, quality of life, adverse events, and outcomes for animals.