Animal-Assisted Therapy With Chronic Psychiatric Inpatients: Equine-Assisted Psychotherapy and Aggressive Behavior

Inpatients at Greystone Park Psychiatric Hospital (GPPH), ≥18 and <65 years, were identified from hospital records and by treatment teams asked to identify patients with aggressive or regressed behavior, which was defined as three or more violent incidents in the preceding 12 months (or two incidents plus clinically perceived active risk) or persistent social isolation and difficulty engaging in discharge-related programs (most in a database maintained by social services of patients discharge-ready for more than 12 months). A large majority of GPPH patients met one or both criteria; the intent was to be inclusive. Exclusion criteria, determined on medical director review, included impaired ambulation, cognitive impairments, or other medical factors that might be exacerbated or result in harm during animal contact. Patients were not referred if their behavior was considered to pose a substantive risk to animals or peers.

Introductory presentations to potential participants on each long-term unit were followed by written informed consent after complete description of the study. Each participant was randomly assigned to one of four groups: EAP, CAP, environmentally enhanced social skills group psychotherapy (SSP) (active control), or regular hospital care (standard control). Active interventions provided for ten 40- to 60-minute weekly group sessions, with groups of up to ten members that were homogeneous on recruitment subtype (aggressive or regressed). EAP, CAP, and SSP were conducted in parallel at 9 a.m., 10:45 a.m., and 1 p.m. Participants in the standard control group received no additional interventions beyond regular hospital treatment. Groups were conducted at dedicated sites on hospital grounds, including suitably configured outdoor areas (EAP) or cottages (CAP and SSP). EAP and CAP session staffing included certified pet therapists, hospital rehabilitation staff, and hospital staff to address emergent clinical issues. Aside from the additional weekly AAT activity, participants’ hospital care was unchanged. The two months preceding enrollment were used as baseline for hospital-derived data; clinical instruments were completed by staff members, who were blind to group assignment, at intake. Outcomes reflected the three months after study initiation.

The active control group involved social skills exercises identical to those in the hospital’s general program, but, as with CAP, they were conducted in an appropriately configured cottage. The setting was intended to control therapeutic factors unrelated to animal interactions, including leaving the hospital building, proceeding to a novel setting, and having added staff attention.

Participants in the standard control group remained in the general hospital, receiving no additional intervention except recruitment procedures and very brief three-month follow-up assessments.

Data from hospital records contrasted the two months preceding intake with the three months postintake. Intake interview measures were obtained from staff with an ongoing clinical relationship with the patient but blind to AAT assignment and compared with measures three months postintake. Staff training sessions on the measures suggested consensus; however, obtaining formal interrater reliability ratings was not feasible. Potential covariates among the clinical and demographic characteristics included age, sex, chart-derived psychiatric and medical diagnoses, hospitalization duration, legal commitment status, and number of intervention sessions attended. Although formal diagnostic assessment using standardized interviews would have been desirable, such assessments were not feasible and not considered essential to the study’s behavioral goals and rationale. Staff members interviewed at follow-up were not blind to patient project involvement; however, many (47%, N=41 of 88 responders) reported limited awareness of AAT assignments, and none had direct involvement in AAT interventions.

Statistical analyses used SPSS (12.0); all tests were two-tailed. To examine intervention effects, these analyses excluded participants assigned to EAP, CAP, or SSP who did not attend any sessions. As a conservative analytic approach, data for all other participants (meaning those with any exposure to the interventions) were included. Intervention group differences in baseline clinical and demographic characteristics were assessed. Outcomes among the four intervention groups were assessed primarily with analysis of variance (ANOVA) in generalized linear models (Tukey post hoc tests). Covariance analyses assessed effects in the violent incidents models.

Of 105 inpatients (from 20 clinical units) signing consent, one was deceased prior to project initiation, 12 did not attend any intervention sessions, and two had insufficient baseline data (admitted less than two months before study intake). Characteristics of the remaining 90 participants are presented in Table 1. Participants’ mean age was 44, 37% were women, 61% were non-Latino Caucasian, and 76% had chart diagnoses of schizophrenia or schizoaffective disorder. Mean hospitalization length was 5.4 years, 56% had civil commitment status or had been committed on the basis of a finding of not guilty by reason of insanity, and 63% were identified for the study primarily for aggressive behavior. There were no significant baseline differences among the four intervention groups (ANOVA or chi square) in age, sex, racial-ethnic background, diagnosis, days from hospital admission to study intake, recruitment for aggressive versus regressed behavior, aggressive incidents in the two months preceding intake, BPRS score, and attitudes toward pets and other animals. Baseline differences were found for the LSP-20 (F=2.83, df=3 and 85, p<.05) and OAS-M items assessing assault against objects (F=2.87, df=3 and 85, p<.05) and global overt irritability (F=3.57, df=3 and 83, p<.02). Post hoc tests found higher baseline OAS-M aggression and life skills dysfunction for EAP- versus CAP-assigned participants (p<.05). Staff expectations of AAT benefit, non–aggression-related incident reports, 1:1 staff observation, seclusion and restraint, visual analog scales, and intrusiveness (GIM) also showed no baseline differences among groups (data not shown).

AAT interventions were well tolerated with no adverse effects requiring medical or psychiatric attention. Sessions ran from mid-March to June 2010; attendance appeared sensitive to weather conditions. The median number of sessions attended was seven each for EAP and CAP and five for SSP; there were no significant differences across groups. Eighty-three percent of EAP (N=20), 80% of CAP (N=20), and 78% of SSP (N=18) participants attended at least three sessions. Of the 90 patients, four were discharged before conclusion of the interventions (one from each group), and three were transferred to a more restrictive forensic hospital (one from CAP and two from SSP).

As shown in Table 2, the four groups differed when the mean number of violence-related incident reports for the two months preceding study intake was compared with that for the three postintake months (p=.035). Violent incident reports (per patient per month) suggested decreases for EAP patients but increases for other groups (Figure 1 and Table 2). Post hoc tests revealed significant differences contrasting EAP and SSP. There was no evidence that CAP reduced violence-related incidents (including use of less stringent least-significant-difference post hoc tests, in which EAP showed reduced incidents compared with incidents reported for each of the other groups, including CAP [data not shown]).

Secondary aggression-related measures also suggested improvement with AAT (Table 2). The OAS-M showed group differences in aggression against objects and persons (p=.05 and p=.053, respectively). Aggression among EAP participants appeared to decrease, compared with increased or unchanged levels for other groups (Table 2), with post hoc tests suggesting EAP benefits (p=.029 versus CAP for objects; p=.074 versus SSP for persons, respectively). Group differences were also suggested for 1:1 observation, often a consequence of aggressive behavior (p=.051), with post hoc tests suggesting benefits of canine (p=.058) as well as equine (p=.082) therapy versus regular hospital care. No differences were evident for seclusion and restraint (Table 2).

Nonviolent incidents showed no differences pre- versus postintervention (Table 2 and Figure 1). Similarly, no AAT effects were found with the BPRS, LSP-20, GIM (Table 2), or mood measures on the visual analogue scales (data not shown).

Covariance analyses revealed that few factors contributed to AAT effects on violence. Adding recruitment rationale (aggressive versus regressed) to the model did not reduce the AAT effect on violent incidents (F=2.97, df=3 and 85, p=.036), nor were effects found for baseline BPRS, LSP-20, or GIM scores; attitudes about pets; or age, sex, diagnosis, or sessions attended. To determine whether the reduction in EAP-related violent incidents was associated with reduced symptoms (BPRS), improved function (LSP-20), or reduced intrusiveness (GIM), we tested pre-post changes with each of these covariates in separate analyses. Change in BPRS score had no effect on violence, with the intervention group effect retained (F=3.03, df=3 and 84, p=.034); improved LSP-20 score was associated with reduced incidents (F=5.41, df=1 and 84, p=.022), with effect of intervention group retained (F=3.01, df=3 and 84, p=.05). Improved intrusiveness was associated with reduced violence (F=5.62, df=1 and 76, p=.02) and with a diminished group effect (F=1.91, df=3 and 76, ns).

Staff expectations of AAT benefits at baseline, before randomization, were associated with AAT effects on violence (rated on a 4-point scale, for “very helpful,” “somewhat helpful,” “little or no help,” and “may be detrimental”). In the model, staff expectations were associated with reduced violent incidents (F=6.99, df=1 and 82, p=.01), and the AAT group effect was retained (F=3.65, df=3 and 82, p=.016). Table 3 shows that violent incidents appeared unchanged among patients in the EAP group for whom staff had lesser expectations, whereas those for whom staff predicted that AAT would be “very helpful” showed a large decrease in incidents.