A new study shows that adopting a pet may enhance the effect of medication in unresponsive depression.
Pet ownership has a number of potential advantages. Pets can keep lonely people company, and serve as catalysts for friendship formation. Many pet owners also find that they get more exercise (e.g., they need to walk their dogs), and that caring for and loving their pets has made their life more meaningful. A number of studies have shown the benefits of regular interaction with animals and pet ownership. To illustrate, a 1992 study found that pet ownership is associated with lower levels of risk factors for heart disease.7
In the present study, Pereira and Fonte attempted to determine if pet adoption could be helpful for people with treat-resistant depression as well.
Initially, the researchers contacted 80 patients (50 females and 30 males) who had treatment-resistant depression and had been receiving medication treatment for 9-to-15 months without any improvement. The researchers encouraged these patients to adopt a pet.
Of these patients, 33 (25 females and 8 males) agreed to adopt a pet. For comparison purposes, the researchers used another 33 individuals who were randomly drawn from the remaining patients—of the ones who did not adopt or already own any pets—to serve as a control group (henceforth known as the non-pet group).
Among the 33 who accepted the pet adoption suggestion, 18 adopted a dog, 7 adopted two dogs, and 7 adopted one cat. The pet and non-pet groups maintained the same medication treatment as before. Neither group was aware of the other’s existence.
The patients were evaluated several times over the following three months. One of the main measures used was the Hamilton Depression Rating Scale (HAMD-17), which includes questions related to guilt, insomnia, and other depressive symptoms. Scoring over 23 on this measure is usually associated with severe depression while scoring less than 7 indicates the absence of depression.
The results, at the end of the 12 weeks, showed that the pet group had made significant improvements, both in comparison to the beginning of the study but also in comparison to the non-pet group.
For example, a third of the pet-group no longer met the criteria for depression (i.e. they scored less than 7 on HAMD-17). The group’s scores on HAMD-17 began to decrease one month into the study, and by the second month, the scores were significantly different from those of the non-pet group.
These results appear to show that pet adoption is helpful in managing treatment-resistant depression. Nevertheless, we must be cautious in interpreting the results, given that the study did not include random assignment. In other words, we cannot be certain that pet ownership was the only major difference between the groups and thus responsible for the different outcomes.
