Presence of Aquariums 1
Running head: AQUARIUMS AND ECT PATIENTS
Effect of Aquariums on Electroconvulsive Therapy Patients
Sandra B. Barker, Ph.D.*
Professor of Psychiatry
Director, Center for Human-Animal Interaction
Virginia Commonwealth University
P. O. Box 980710
Richmond, VA 23298-0710
Keith G. Rasmussen, M.D.
Assistant Professor of Psychiatry
Mayo Clinic Department of Psychiatry
200 1st Street SW
Rochester, MN 55905
Al M. Best, Ph.D.
Associate Professor of Biostatistics
Virginia Commonwealth University
P. O. Box 980032
Richmond, VA 23298-032
Anthrozoös, (16)3, 229-240
Presence of Aquariums 2
This study investigates the effect of an aquarium on pre-treatment anxiety, fear.
frustration, and depression in electroconvulsive therapy (ECT) patients. Forty-two patients
consecutively referred for ECT were rotated between rooms with and without aquariums. Self
report measures of depression, anxiety, fear, and frustration were obtained along with heart rate
and blood pressure. Preliminary mixed model, repeated measures analysis of variance
(ANOVA) revealed no significant differences between the aquarium and control conditions on
any of the dependent measures. A trend toward significance was found for self reported anxiety
(p =0.08) and further data was collected. Subsequent mixed model, repeated measures ANOVA
confirmed the trend toward differences (p = 0.08) in anxiety between the aquarium and control
condition. Factoring out demographic factors, the average subject experienced 12% less anxiety
in the presence of an aquarium.
Presence of Aquariums 3
Effect of Aquariums on Electroconvulsive Therapy Patients
Electroconvulsive therapy (ECT) is a well-established, effective psychiatric treatment
that is being more widely used, primarily for the treatment of serious mood disorders such as
depression (Harrison and Kaarsemaker 2000). However, one problem that has been recognized
for many years is that patients undergoing ECT often experience fear and anxiety related to
treatment (Gallinek 1956; Freeman and Kendell 1986; Fox 1993). Gomez (1975) reported that
75% of her patients feared ECT, with fears related to memory loss, death, and brain damage.
Between 29% and 40% of patients found ECT to be frightening (Freeman and Kendell 1980;
Benbow 1988). While the effectiveness of ECT has been firmly established, fear and anxiety
have been associated with reduced treatment compliance and treatment refusal (Freeman and
Kendell 1980; Benbow 1988; Fox 1993). Some practitioners have attributed increased fear and
anxiety to lack of information, others attribute these symptoms to unknown aspects of the
treatment itself (Fox 1993; Harrison and Kaarsemaker 2000).
Educational interventions have been primarily developed to address this fear and anxiety;
however conflicting results have been reported regarding their effectiveness. One study focused
on the effect of emotional support, provided by a psychiatric nurse in an educational context, on
the anxiety levels of 32 ECT patients (Cohen 1970). The results revealed no significant
difference in anxiety levels between patients receiving the intervention and those who did not.
Another study involving 37 veteran psychiatric patients reported that while knowledge and
behavioral intent showed positive changes following an educational ECT video, there was no
reduction in fear (Battersby, Ben-Tovim, and Eden 1993). Contrary results were reported using a
continuous quality improvement model in which an educational video and written information
were found to reduce anxiety. These findings are based on followup telephone interviews from
15 patients (Harrison and Kaarsemaker 2000).
The effect of environmental interventions to calm ECT patients has received little
research attention. One environmental intervention, animal-assisted therapy (AAT), has been
found to calm patients in some circumstances. The benefits of interacting with companion
animals are receiving increased attention in the healthcare industry. Studies have documented
reduced cardiovascular risk factors, improved one year survival rates following myocardial
infarction, reduction in minor health problems, and lower physician utilization associated with
pet ownership (Friedman, Katcher, Lynch, and Thomas 1980; Siegel 1990; Serpell 1991;
Anderson, Reid, and Jennings 1992). More recent, randomized controlled studies have shown a
positive effect of pet ownership or the presence of pets in physiological indicators of reactive
stress ( Allen, Blascovitch, Tomaka, and Kelsey 1991; Allen 2000; Allen, Shykoff, and Izzo
2001; Allen, Blascovich, and Mendes 2002;). Interacting with companion animals has also been
associated with reduced anxiety levels for non-psychiatric as well as inpatient psychiatric
populations (Wilson 1991; Barker and Dawson 1998;). A significant reduction in anxiety was
reported in a study involving 241 hospitalized psychiatric patients with a broad range of
diagnoses following 30 minutes of animal-assisted therapy (Barker and Dawson 1998). A more
recent study found a significant reduction in fear following a 15-minute interaction with a
therapy dog and its handler for 35 psychiatric patients waiting for electroconvulsive therapy
Presence of Aquariums 4
(Barker, Pandurangi, and Best 2003). No significant differences were found for anxiety or
A challenge faced by those incorporating therapy dogs into healthcare facilities is
securing volunteers with therapy animals who can provide frequent and consistent services.
Incorporating fish aquariums into healthcare facilities eliminates these challenges. Aquariums
enable more frequent, longer, and consistent exposure to the intervention without involving
volunteers, but requires financial investment in the purchase or lease, and maintenance of the
aquariums. This study was undertaken to determine if aquariums would provide some of the
same benefits for hospitalized psychiatric patients as therapy dogs have been reported to provide.
Several studies have explored the benefits of fish aquariums in healthcare settings with
equivocal results ( Katcher, Segal, and Beck 1984; Cole and Gawlinski 2000; Edwards and Beck
2002). While Katcher et al. (1984) found that physiological indicators of anxiety, blood pressure
and heart rate, were not significantly lower in patients contemplating an aquarium prior to dental
surgery when compared with a comparison and control group, subjective reports of calming were
significantly different with contemplation of an aquarium associated with more comfort and
relaxation. It is important to note that subjects in this study were told to anticipate a calming
benefit from focusing on the aquarium. Cole and Gawlinski (2000) explored the effect of a salt-
water fish aquarium on levels of stress, anxiety, depression, and hostility in a small (n=10)
sample of patients waiting for orthotopic heart transplantation. While the authors found no
statistically significant reductions on any of the variables assessed, they did note other benefits of
the fish aquarium, including the successful introduction of animal-assisted activities into the
intensive care environment, the provision of cognitive stimulation, and patient subjective reports
of delight and calm associated with the fish aquarium. A more recent study found important
benefits to patients with Alzheimer’s disease (Edwards and Beck 2002). Patients observing
aquariums while dining showed significant increases in nutritional intake and weight over a 16-
The current study investigated whether the presence of an aquarium is associated with
reduced physiological levels of anxiety and self reported anxiety, fear, depression, and
frustration in psychiatric patients waiting for scheduled electroconvulsive therapy (ECT).
Depression was included as the null hypothesis, as was done in the Barker, Pandurangi, and Best
(2003) study with ECT patients. It was not expected that brief exposure to an aquarium would
impact depression that had not responded to pharmacological treatment and that was of a severity
to warrant ECT.
The study was a within-subject design in which subjects served as their own controls.
Subjects were alternately assigned to the treatment condition (an aquarium present in the ECT
Holding Room) or the control condition (absence of aquarium in the ECT Holding Room) on
subsequent ECT treatment days. Pre and posttest measures of anxiety, depression, fear, and
frustration were collected for both conditions prior to ECT treatment.
Presence of Aquariums 5
Following approval of the study by a university committee for the protection of human
subjects, outpatients consecutively scheduled for electroconvulsive therapy were invited to
participate in the study. These patients were referred for ECT by psychiatrists in the community,
from within the health system in which the study took place, or from other hospitals. These
patients typically have severe depression or bipolar disorder that has not responded to
The intervention consisted of two ten gallon, fresh water, self contained, fish aquariums,
measuring 20 inches long, 10 inches wide, and 12 inches high. Each aquarium contained
approximately five colorful and hearty (African Cichlid variety) fish, colorful gravel and
decorations, a deep blue background, oxygen pump, light, and self-feeder. They were cleaned
and maintained on a biweekly basis by an aquarium leasing company. Each aquarium was placed
on a 28 inch tall cabinet. An aquarium was placed in two of the four holding rooms used for
patients waiting for ECT. Four private patient rooms located adjacent to the ECT Treatment
Room are designated as holding rooms to provide patients with a private room for changing
clothes and waiting for their ECT treatment as well as recovering following treatment. These
rooms are equipped with furniture, but contain no television, radios, or magazines.
Visual analog scales (VAS) were used to assess depression, anxiety, frustration, and fear.
They were selected for their simplicity and ease of use. The variables were defined globally on
the VAS scales in terms of how much (depression, anxiety, fear, and frustration) the subject felt
at the time. These scales, each 15 cm long and anchored at each end with descriptors of “none”
to “the most severe imaginable” have been used successfully with psychiatric patients with
acceptable levels of reliability and validity (Barker, Pandurangi, and Best 2003). Reported test-
retest (r = 0.45 - 0.78, p = 0.0001) correlations on these scales support their reliability and
significant post intervention correlations (r = 0.65 - 0.68, p = or < 0.01) between patient and
nurse ratings support their validity (Barker, Pandurangi, and Best 2003). Patients simply place a
line on each scale to indicate the intensity of each feeling.
Physiological assessments of anxiety included measurements of heart rate and blood
pressure using an oscillometric, automated device, Dinamap XL Vital Signs Monitor. The
Dinamap Monitor is routinely used in the hospital for assessing blood pressure and heart rate
prior to ECT. Reliability and accuracy of the device has been demonstrated in several studies
(Bruner, Krenis, Kunsman, Sherman 1981; Baker 1986; Mundt, Chambless, Burnham and Heiss
1992; Bald, Kubel, and Rascher 1994; Gardner and Montgomery 1998). It is autocalibrated and
annually tested with a calibrated standard to verify that the transducer is accurate. Blood
pressure was consistently taken in the same position, either sitting or lying, and the cuff was
consistently placed on the same area of the upper arm to insure reliability of the measure.
Demographic information was collected on gender, age, marital status, smoking status,
diagnosis, and previous number of ECT treatments. These variables were assessed since they
Presence of Aquariums 6
could have an effect on the dependent variables, thereby representing intervening variables if not
controlled in the analysis. Marital status was included since it may represent social support that
could affect levels of dysphoria as well as blood pressure. Since some evidence indicates that
fear and anxiety increase in ECT patients as they continue in treatment (Fox 1993), the authors
believed it was important to control for prior treatment. Also, since ECT patients who smoke are
requested to refrain from smoking after midnight the night before ECT, they may experience
increased anxiety related to nicotine withdrawal. Therefore smoking was also controlled in the
Patients were assigned to holding rooms based on a first come basis. ECT nurses were
instructed to alternate assigning patients to holding rooms with and without an aquarium.
Patients were not told about the aquarium or asked to look at it to minimize demand
characteristics. On a subsequent treatment day, patients were assigned to the alternate condition.
The ECT nurse was instructed to take vital signs as soon as patients were taken to their holding
rooms. Nurses were instructed to take vital signs again, after approximately 20 minutes and prior
to the ECT treatment, making sure to take vitals with the patient in the same position (sitting or
lying) as the initial readings. They then asked patients to complete the visual analog feelings
scales presented in random order.
One investigator scored all of the visual analog scales in millimeters using the same
metric ruler. Scores ranged from 0 – 15, with higher scores indicating higher levels of reported
Basic demographic variables of age, gender, marital status, smoking status, previous ECT
treatments, and primary diagnosis were collected from patient records by one of the
A mixed-model repeated-measures analysis of variance was used to determine the effect
of aquarium presence on anxiety, fear, frustration and depression. In addition to the primary
independent variable of aquarium presence (aquarium or control), the following demographic
factors were included in the ANOVA: gender (male or female), current smoking status (yes or
no), age (continuous), diagnosis (depression or other), marital status (married, divorced, single,
widowed, or separated), and number of prior ECT treatments (continuous). A single analysis was
performed for each dependent variable to test for the effect of aquarium presence or absence
(repeated measure), after the effects of demographic characteristics were covaried out.
Forty-two subjects participated in the study. Most of the subjects were female (74%, n =
31) and ranged in age from 21-82 with a mean age of 48.4 (sd = 16.5). Forty-three percent (n =
Presence of Aquariums 7
18) were married, 19% (n = 8) divorced, 26% (n = 11) single, 7% (n = 3) widowed and 2% (n =
1) separated (one subject’s marital status was not documented). Close to three-fourths (74%, n =
31) of the patients were diagnosed with depressive disorder and had undergone previous ECT
treatments (mean = 3.7) prior to the study. Twenty-four percent (n = 10) of the subjects were
Preliminary mixed model repeated-measures analysis of variance was run after 192
observations had been collected. This included 31 patients, 25 of whom experienced both the
aquarium and control conditions at least once. Results revealed no statistically significant
difference at p = 0.05 between the aquarium and control conditions for heart rate, systolic blood
pressure, diastolic blood pressure, self reported levels of fear, frustration, anxiety, and
depression. There was a marginally significant difference at p = 0.08 for self reported anxiety. A
power analysis suggested that increasing the study size to 282 observations (37 subjects) would
yield 70% power.
Based on the preliminary results and power analysis, data collection continued only for
anxiety for 108 additional, consecutive ECT treatments. This resulted in data collection on a
total of 42 subjects and 300 observations. Table 1 shows the distribution of the number of
observations and subjects under the aquarium and control conditions. Factoring out the
demographic variables, the trend toward differences in anxiety (p = 0.08) was confirmed
between the treatment and control conditions on anxiety (analysis based on 30 subjects receiving
both conditions). Table 2 shows the least squares means, standard errors, and F ratios for all of
the dependent variables. The average subject was found to experiences 12% less anxiety with an
aquarium than without one. Although there was a trend to significance, the power analysis
indicates that the small effect size will not become statistically significant until a study at least
twice as large as this one is performed. A study twice as large would have a power of 77% (at
alpha = 0.05).
Discussion and Conclusions
Preliminary analysis showed no statistically significant difference on any of the
dependent variables between the aquarium and control conditions. A marginally significant
difference at p = 0.08 was found for anxiety level assessed by visual analog scale. Based on a
power analysis, increased numbers of observations were collected for anxiety. The results
confirmed the trend toward differences (p = 0.08) in anxiety between the aquarium and control
conditions. The trend was toward lower anxiety levels in the aquarium condition. It is important
to note that while the total number of observations was increased to 300 (subjects = 42), the
number of observations included in the analyses was limited to 213, the number of observations
for the 30 subjects who received both conditions. Not all subjects received both conditions
because of the limited number of available holding rooms (n = 4), to which patients had to be
assigned as they arrived for treatment. Since this study was conducted in an active clinical
setting, treatment could not be delayed to accommodate the study. Therefore the targeted number
of observations based on the initial power analysis was not reached (213 observations compared
to 282 indicated by the power analysis). Because of the small effect size, the negative findings
Presence of Aquariums 8
of the current study are inconclusive. Power analysis indicates that a study at least twice as large
as the current one is needed for the small effect size to reach statistical significance. In light of
the confirmed trend toward reduced anxiety, further studies with larger subject numbers are
In addition to the study limitation of sample size, subjects were not randomly selected
and caution should therefore be used in generalizing these findings to other psychiatric
populations. Finally, while standard measurements were used to score the visual analog scales,
the researcher performing the measurements was not blind to the conditions. In an attempt to
minimize bias, a random sample of scales was rescored with 100% agreement.
Similar to the results reported by Katcher, Segal, and Beck (1984), blood pressure and
heart rate were not significantly different for the aquarium and control conditions. The presence
of an aquarium was not associated with reduced physiological measures of anxiety in patients
waiting for ECT. However, unlike the earlier Katcher study, patients in this study were not
asked to look at, or in any way attend to, the aquarium, nor was it suggested to them that the
aquarium would have a calming effect. Instead, the purpose of this study was to assess the
impact of the mere presence of a fish aquarium. Further studies are needed in which patients are
instructed to watch the fish.
The lack of significant findings may be in part due to the background role of the
aquarium in this study. Since patients were not seated in front of the aquarium or asked to look
at it, patients were not intentionally exposed to the potentially calming effect of watching the fish
unless they deliberately chose to do so. Most patients tended to lie down while in the holding
rooms. In order to view the fish in this position, they would have to deliberately lie on one side.
It may be necessary for patients to focus on the aquarium to derive benefit; a task that may be
difficult for severely depressed patients. Also, the aquarium may not represent a powerful
enough stimulus to distract patients from thoughts of their upcoming ECT treatment.
While a similar study with ECT patients, involving therapy dogs rather than aquariums,
also found no significant reduction in anxiety or depression, the intervention with the therapy
dog significantly reduced fear (Barker, Pandurangi, and Best 2003). The aquarium intervention
did not significantly impact fear. These inconsistent findings may be due to the difference in
interaction associated with the two species. A self-contained aquarium requires no interaction
with the patient whereas a therapy animal, such as a dog, is more apt to promote interaction in
the form of petting and talking. The entrance of the therapy dog and handler into a patient’s
room almost always results in the patient attending to them, whereas the presence of an aquarium
in the holding room into which the patient is led may not. Also, physical interaction with the fish
is not possible, whereas physical interaction with the dog was readily available. Observing an
aquarium is a more passive experience compared to the active experience of petting or talking to
or about a dog. Perhaps it is more active interaction, such as physically petting the dog that is
needed to impact fear. More research is needed to investigate the components of animal-assisted
activities that contribute to symptom reductions.
Presence of Aquariums 9
Since neither study resulted in a significant reduction in anxiety, it may be that the
anxiety related to the ECT procedure is not amenable to the calming effects of animal-assisted
activities. Or the global nature of the visual analog scales used in both studies may not be
sensitive to anxiety changes resulting from animal-assisted activities.
Positive benefits of the aquariums were noted in positive patient comments about them.
Some patients named the fish and staff frequently commented positively on the presence of the
aquariums and expressed the desire to keep them on the unit. They reported soothing and
calming effects related to the visual and auditory aspects of the aquariums. The cost of
acquisition, set-up, lease and full maintenance of both ten gallon fish aquariums used in this
study totaled $965 a year. Whether the potential benefits justify the cost of incorporating fish
aquarium into psychiatric settings remains to be seen. While our preliminary study documented
a trend towards less anxiety with the presence of an aquarium, it remains for a larger or more
controlled study to confirm this finding.
Presence of Aquariums 10
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Presence of Aquariums 12
Distribution of Observations and Subjects Receiving
Aquarium and Control Conditions
Number of Number of subjects
Observations Aquarium Control
0 9 3
1 6 10
2 9 5
3 5 8
4 5 2
5 3 6
6 1 1
8 1 2
12 1 1
15 1 1
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total 42 42
Presence of Aquariums 14
Least Squares (LS) Means and Standard Errors (SE) for Depression, Anxiety, Frustration, Fear,
Heart Rate, and Blood Pressure for Patients in Rooms with and without a Fish Aquarium Prior to
Condition LS 95% Confidence
N* Mean SE Interval DF F p-value
Depression (n = 20 subjects)
aquarium 62 3.26 1.81 0.05 7.19
control 98 4.34 1.78 0.82 7.86 1,139 1.6 0.2101
Anxiety (n = 30 subjects)
Aquarium 119 5.53 0.95 3.66 7.40
Control 145 6.26 0.95 4.40 8.13 1,233 3.0 0.0848
Frustration (n = 20 subjects)
Aquarium 62 2.13 1.76 -1.35 5.61
Control 98 1.99 1.73 -1.43 5.41 1,139 0.0 0.8266
Fear (n = 20 subjects)
Aquarium 62 2.84 2.53 -2.16 7.83
Control 99 2.50 2.51 -2.46 7.47 1,140 0.5 0.4939
Heart Rate at Baseline (n = 30 subjects)
Aquarium 121 80.28 2.96 74.47 86.09
Control 148 79.21 2.95 73.42 85.00 1,400 0.9 0.3561
Heart Rate Post Condition (n=30 subjects)
Aquarium 64 76.66 3.09 70.59 82.73
Control 100 76.87 3.02 70.93 82.81 1,400 0.02 0.8889
Systolic Blood Pressure at Baseline (n = 30 subjects)
Aquarium 122 130.28 3.99 122.44 138.12
Control 149 130.48 3.97 122.67 138.28 1,400 0.01 0.9141
Systolic Blood Pressure Post Condition (n = 30 subjects)
Aquarium 122 129.61 4.24 121.28 137.94
Control 149 130.13 4.11 122.05 138.21 1,400 0.05 0.8259
Diastolic Blood Pressure at Baseline (n = 30 subjects)
Aquarium 122 74.21 2.12 70.04 78.38
Control 149 73.38 2.11 69.23 77.53 1,400 0.58 0.4470
Diastolic Blood Pressure Post Condition (n = 30 subjects)
Aquarium 122 72.32 2.28 67.83 76.81
Control 149 72.10 2.20 67.77 76.43 1,400 0.02 0.8778
*N = number of observations