This is a quantitative cross-sectional observational study.

A total of 221 individuals were recruited from the general community in Brazil, primarily from the southern region. Recruitment occurred through social media platforms (Facebook and Instagram). In addition, part of the sample was recruited from existing contact lists of older adults who had previously participated in research studies conducted at the Pontifical Catholic University of Rio Grande do Sul. Posts and messages contained standardized text explaining the study objectives, eligibility criteria, and a contact link for interested participants. Individuals who expressed interest were contacted individually via WhatsApp to confirm eligibility before scheduling the interview. The participants were divided into 2 groups: 1 group consisted of participants who owned pets and the other consisted of individuals who did not own pets.

Eligible participants were community-dwelling older adults aged 59 years or older, who scored more than 14 points on the Modified Telephone Interview for Cognitive Status (TICS-M) [28], were literate, and did not have uncorrected hearing problems that could interfere with completing the instruments. All participants provided electronic informed consent before data collection. A total of 6 individuals who did not complete the entire questionnaire were excluded from the study. The final sample consisted of 215 participants.

The Sociodemographic Questionnaire was used to collect information regarding the sociodemographic characteristics of the sample.

The TICS-M was employed to assess the cognitive functions of the participants. The original 41-item version (TICS) was developed to identify cognitive decline through a telephone interview [29]. In its modified version (TICS-M), 2 items were altered to include a measure to assess late memory [30]. This instrument has been translated and validated for the Brazilian population in a sample of elderly stroke survivors, showing a Cronbach α coefficient of 0.93. The Brazilian version of the questionnaire identified 3 domains: working memory, recent and late memory, and orientation [28].

Cognitive Reserve Index Questionnaire (CRIq) was applied to assess the cognitive reserve of the participants. This questionnaire consists of 20 items grouped into 3 subscales (CRIq Education, CRIq WorkingActivity, and CRIq LeisureTime). The total score of the instrument is calculated by adding up the subscores of the 3 subscales. The original version of the CRIq has a Cronbach α coefficient of 0.73 [31], and this questionnaire already has a version translated into Brazilian Portuguese [32], which was used in this study.

Mental Health Continuum-Short Form (MHC-SF) was used to assess positive mental health. It consists of 14 items presented in a Likert scale format, ranging from 1 (never) to 6 (every day). The MHC-SF has 3 subscales that assess subjective or emotional well-being, psychological well-being, and social well-being [33]. In this study, we applied the translated and validated version of the MHC-SF for the Brazilian population, which shows adequate reliability with a Cronbach α of 0.96 [34].

Geriatric Depression Scale (GDS-15) was used to measure the participants’ depression symptoms. The GDS is specifically designed for older adults and addresses depression symptoms experienced in the week preceding the questionnaire application. The short version consists of 15 items, with responses classified as “yes” or “no.” The total score is calculated by adding up the responses selected by the respondents [35]. In this study, we used the translated and validated version for the Brazilian context, which presents adequate reliability coefficients according to the paired Wilcoxon test (z=1.60; P=.11), Spearman correlation (ρ=0.86; P<.001), and weighted kappa (κ=0.64) [36].

Geriatric Anxiety Inventory (GAI) was used to assess symptoms of anxiety. This instrument consists of 20 items in which participants indicate whether they agree or disagree with the statements, considering the week before the questionnaire was applied [37]. In this study, we used the translated and validated version for the Brazilian population, which has a Cronbach α coefficient of 0.90 and significant test-retest reliability (ρ=0.85, P<.001) [38].

Data collection was conducted through individual video calls using the WhatsApp messaging app. During each session, participants’ responses were entered in real time into the Qualtrics platform by the researcher. All data were collected by trained psychology students who received prior instruction and supervision to ensure the standardized administration of the instruments. The data collection period extended from April to September 2023.

The study was approved by the Research Ethics Committee of the Pontifical Catholic University of Rio Grande do Sul (approval number: 65996522.5.0000.5336) and complied with national and institutional ethical standards for research involving human participants, in accordance with Resolution No. 466/2012 of the Brazilian National Health Council and Resolution No. 016/2000 of the Federal Council of Psychology. All participants received an electronic informed consent form outlining the study’s objectives, potential risks and benefits, anonymity, and voluntary nature of participation. Only those who agreed to the consent form were included in the study. Participants were assured of the confidentiality of their data and their right to withdraw from the study at any time without any consequences. Data were collected and stored anonymously, and no personally identifying information was retained or linked to participant responses. Participants did not receive financial compensation or any other form of remuneration for their participation.

The data were analyzed using the JASP software (version 0.18.3.0. JASP Team). Quantitative variables were described using means and standard deviations, while categorical variables were presented in terms of absolute and relative frequency. The normality of the univariate distribution of the variables under investigation was assessed using the Shapiro-Wilk test, adopting a significance level of P<.05. Since all variables in this study violated the assumption of normality, nonparametric statistical tests were employed. To compare the groups, the Mann-Whitney U test was conducted, followed by a rank-biserial correlation (r_b) to assess the magnitude of the effect size found.

This study aimed to compare symptoms of depression, anxiety, and levels of psychological and cognitive well-being between older individuals who owned pets and those who did not. The results showed that pet owners presented fewer symptoms of depression compared to non–pet owners, whereas no significant differences were observed for anxiety, cognitive functioning, or cognitive reserve.

The observed association between pet ownership and lower depressive symptoms aligns with previous findings, suggesting that companion animals can mitigate depression symptoms among older individuals who had experienced loss, such as a divorce or the death of a spouse [21]. Furthermore, in another study, older individuals who frequently engaged in activities with their pets reported lower levels of depression symptoms, regardless of factors such as age, gender, and education. However, this effect was not observed when considering only the presence of a pet [39].

Friedmann et al [19] proposed the biopsychosocial model as a framework to explain how companion animals may help minimize depressive symptoms in their owners. According to this perspective, pet ownership can influence health through the interaction of biological, psychological, and social factors. The presence of an animal may enhance the social dimension by providing companionship and emotional support, which can improve the psychological state through social support or other mechanisms, such as reducing depression, stress, and anxiety, and ultimately promote positive health outcomes in older adults [19].

However, not all studies have found the same association. Sharpley et al [40], in a longitudinal study, reported that older individuals with more symptoms of depression were more likely to own a dog. However, in this study, pet ownership was not associated with changes in symptoms of depression over time [40]. Similar results were observed in the study by Mueller et al [41], where pet ownership was associated with a higher likelihood of having experienced symptoms of depression over the course of life. In contrast, no relationship was found between current depression and pet ownership [41].

In another investigation, cat owners exhibited more symptoms of depression in comparison to dog owners or older individuals without pets [42]. These results were corroborated by other studies that also found no evidence of an association between having a pet and symptoms of depression in the older population [19,24,43,44].

One possible explanation for these inconsistencies is that while some older individuals may benefit from living with pets, for others, the responsibility of caring for an animal could be detrimental [24]. This may be due to the stress caused by the commitment or difficulties in meeting the pet’s needs [42]. The responsibility of taking care of a pet might interfere with the individual’s freedom, limiting outings and travel. Financial concerns, such as the costs of food and veterinary care, may also cause worries for some pet owners [45,46].

As for anxiety symptoms, no significant differences were found between the groups. This result also shows contradictory findings across studies. While some research has not observed differences in anxiety symptoms when comparing older individuals with and without pets [19,47], the results from Bolstad et al [48] suggest that having a pet during old age is associated with lower anxiety symptoms. Additionally, the systematic review conducted by Hughes et al [49] concluded that interaction with companion animals can alleviate anxiety symptoms in older individuals. Moreover, a study that evaluated mental health outcomes in older individuals with dogs concluded that the frequency of contact with a dog might be associated with lower anxiety levels [20].

Regarding psychological well-being, the results of this study did not indicate significant differences between the groups. This finding is consistent with previous studies that also found no differences when comparing the psychological well-being of older individuals with and without pets [19,47]. However, the study by Hui Gan et al [46] does not support these findings, highlighting the positive effect of pets on the well-being of older individuals. Furthermore, recent research suggests that owning a dog may be effective in enhancing the psychological well-being of socially isolated older individuals. However, the authors of the study highlight that this effect was not observed among cat owners [50].

As observed by Bennett et al [47], merely owning a pet may not be associated with substantial differences in the well-being of older individuals, a point also noted by studies investigating other psychological measures, such as anxiety and depression symptoms [39,47]. This observation may help explain the inconsistencies in the scientific literature that evaluated human-animal interactions [47]. Recent research conducted with adults supports this hypothesis, indicating that interactions with animals may have a protective effect against negative feelings. These studies show that tactile interactions and activities like playing with, caring for, and training the animal are associated with greater well-being among pet owners [51-53]. Thus, it may be more important to consider the frequency of contact with the pet rather than merely evaluating the presence of a pet [47].

Additionally, comparing these studies is challenging due to their methodological differences, such as the use of different instruments to assess the same constructs and the heterogeneity of their samples. It is also important to consider that mental health is influenced by various factors, and pet ownership is just 1 aspect. Therefore, it is crucial to investigate other elements that also affect mental health [54]. In this study, these sources of variability were minimized by employing validated assessment instruments and standardized procedures for data collection, as well as by including a relatively homogeneous sample in terms of education and cognitive level.

When assessing the cognitive level and cognitive reserve of the participants, no significant differences were found between the groups. An earlier study also found no association between cognitive function and pet ownership [26]. However, other studies reveal that older individuals who own pets exhibit better cognitive function compared to those who do not [22,23,43]. Furthermore, the study by McDonough et al [55], conducted with participants up to 74 years old, indicated that pet ownership was associated with higher levels of cognition and larger brain structures, especially among dog owners. Thus, we can infer from these studies that pet ownership may also be associated with a higher level of cognitive reserve.

The inconsistencies observed in these research results may be due to the different methods used to assess cognition. Additionally, evidence suggests that long-term pet ownership (more than 5 y) is what might provide cognitive benefits for older individuals [56]. Since the time spent with the pet was not included in the analyses of this study, and some studies did not mention whether this variable was evaluated [43,43], this may be an alternative explanation for the discrepancies found between the results.

However, the lack of significant differences between the groups regarding cognitive level and cognitive reserve reinforces the finding that indicates fewer depression symptoms among pet owners. Considering the relationship between depression symptoms and cognitive decline in older individuals [57,58], the absence of differences in cognitive levels and cognitive reserve suggests that variations in depression symptoms between groups cannot be attributed to differences in cognitive function. Instead, it is more likely a direct result of the influence of pet ownership. Thus, pet ownership may act as a protective factor against depression symptoms in the older population.

These findings should be interpreted with caution due to several limitations. First, the cross-sectional design precludes causal inferences. Second, the data were based on self-reported measures, which may be subject to response bias. Additionally, the study did not assess the duration or nature of pet ownership, factors that could influence psychological outcomes. Moreover, the sample was primarily composed of highly educated older adults with preserved cognitive functioning from southern Brazil, which may limit the generalizability of the results to other populations.

Future studies should investigate the activities performed with pets to gain a better understanding of how pet ownership can influence the psychological health of older individuals. Additionally, future studies must explore this association with larger samples and use a longitudinal design to examine the effect of pet ownership on depressive symptoms over time.

Despite the mentioned limitations, the results of this study are relevant, as they compared groups with similar cognitive characteristics, suggesting that the differences found may be attributed to the presence of pets. Therefore, the present findings indicate that pet ownership may be associated with fewer depressive symptoms in older adults, although no significant effects were observed on cognitive reserve, cognitive functioning, anxiety, or psychological well-being. These findings highlight the potential role of companion animals as a source of emotional support in later life. Moreover, these findings have practical implications, as encouraging community initiatives that foster human-animal interaction, such as volunteer programs in shelters or animal-assisted physical activities, may help mitigate depressive symptoms in older adults while also promoting animal welfare.