1. INTRODUCTION
Diseases and dysfunctions increase with older age [1]. A number of studies have demonstrated that pets enhance older people’s health [2-5]. Enmarker et al. [6] found that this was true for older owners of dogs but not for older owners of cats. However, differences in personality may affect self-perceptions of health [7]. For example, Weiss and Costa [8] showed that neuroticism may be a protective factor for physical illness. Conversely, studies found that neuroticism could predict poorer physical health and poorer subjective well-being [9-11]; yet other studies have not shown any relationship between the two at all [12]. Because of these conflicting results, Metha and Gosling [13] suggest that additional factors may explain the effect of neuroticism on health.
It is assumed that the preference for pets as either cats or dogs varies with the individual’s personality [14]. In accordance, Gosling, Sandy and Potter [15] found that people who considered themselves to be “dog people” were more extroverted than “cat people”, while the latter were more neurotic. When comparing pet and non-pet ownership, Parslow et al. [16] found that older men who own pets were more extroverted than those without animals. But the findings are not consistent. Johnson and Rule [17] did not find any differences between “dog people” and “cat people”.
Studies of personality have been guided by different perspectives [18]. The major approach is the trait theory, which believes that personality consists of traits that make individuals behave and react in a certain way depending on a dominant characteristic trait. Human personalities can be divided into different dimensions such as extraversion (vs. introversion) and neuroticism (emotional stability vs. instability) [19,20]. Extraversion includes assertiveness, adventurousness, sociability, outgoingness, and positive emotions, while neuroticism consists of anxiety, irritability, moodiness, shyness, vulnerability, and depression [21]. In a cross-cultural comparison of people aged 16 - 60 years in Norway and England, Eysenck and Tambs [22] found that both Norwegian men and women were less likely to be neurotic than those participants from England. Other studies have shown that women are more likely to be neurotic compared to men [23,24]. While research has shown differences in specific issues, it has not found any general gender differences in extroversion [25].
Srivastava et al. [26] found that, compared to younger people, older people are more emotionally stable with age, but also have a tendency toward greater introversion [27-29]. However, most longitudinal studies indicate that human personality characteristics are stable throughout adult life [30-32].
Since there is a lack of studies with large samples that examine the relationship between pets, older peoples’ personalities and health, the aim of this population study was to identify personality traits among older (>65 years) male and female owners of cats and dogs and to compare their general health status in relation to their personality. Further, the aim was to examine if current cat and dog ownership could be predicted by personality and/or health.
2. METHOD
2.1. Sample Population
The present cross-sectional population study from the North-Trøndelag Health Study (HUNT) in Norway included a total of 1897 cat or dog owners between 65 years and 101 years of age (M = 74.8, SD = 6.45). In Table 1 the distribution of pet ownership between cats and dogs can be seen. This HUNT study was carried out between 2006 and 2008 in Nord-Trøndelag County. It is one of 19 counties in Norway and contains 3% of the national population. The county is fairly representative of Norway as a whole when demographic and geographical factors are considered but it contains no big cities.
From the descriptions of the pet owners, it can be seen that the proportion of cat owners is highest among the oldest segment (80 years - 101 years). Otherwise, there were no significant differences in the demographics of dog owners and cat owners.
2.2. Measures
Besides age, gender and marital status, there were questions about pets, personality and general selfrated health status.
2.2.1. Questions about Animals/Pets
There was one question about pets/animals: Are there any pets in your home? (cat, dog, other fur-bearing animal/bird).
Table 1. Demographics of cat and dog ownership in numbers and percentage.
Note. Marital status will not be used in further analysis; ***p < 0.001.
Since the aim was to compare cat and dog ownership, owners of other fur-bearing animals and bird owners were excluded.
2.2.2. Personality
To measure extraversion (versus introversion) and neuroticism (emotional stability versus emotional instability), an abbreviated form of the Eysenck Personality Questionnaire (EPQ) was used. Extroversion (E) was measured by six questions about how social the person claims to be (α = 0.70). Neuroticism (N) was measured by six questions on emotional stability (α = 0.71). Only those people who had answered all six questions were included in the analyses. From previous HUNT 3 studies [33], E was classified as low, introversion (0 - 3) and high, extraversion (4 - 6); and N was classified as low, emotional stability (0 - 2) and high, emotional instability (3 - 6) in the analyses. The mean for people aged 65 years and above included in the present HUNT 3 study was for Extraversion 3.08, and for Neuroticism 1.61.
2.2.3. Self-Rated General Health Status
The participants’ self-rated general health status was graded into one of four response alternatives (very good, good, poor, and very poor). For the analyses, the alternatives were pooled into good (very good and good) and poor (poor and very poor) health.
2.3. Data Analysis
For the two first aims, Pearson chi-squared statistic analyses were performed. In the analyses of health, age was controlled for. For the final aim, a logistic regression model was carried out. The computer program SPSS for Windows (version 19.0) was used and the p-value 0.05 was used as the level of significance for all analyses.
2.4. Ethical Considerations
HUNT-3 was permitted by the Norwegian Data Inspectorate and by the Regional Committee for Medical Research. All participants in HUNT-3 gave written informed consent. Moreover, the present study was approved by the Board of Research Ethics in Health Region IV of Norway, reference number 2009/813-2.
3. RESULT
3.1. Personality in Cat and Dog Owners
The first aim was to compare older male and female cat and dog owners on measures of extraversion and neuroticism. Independent of pet ownership, the share of selfrated extraverted persons in our sample was 50.7%. The corresponding figure for neuroticism was 13.7%. There were more women (n = 163) who displayed high neurotic traits than men (n = 84), p < 0.001. For extroversion, however, there were no gender differences (p > 0.05). Women (n = 467) and men (n = 448).
In Table 2 we see that among cat owners, there was a higher proportion of men who rated themselves as introverted rather than as extroverted. For neuroticism there were no significant gender differences. However, when comparing men and women with a high degree of selfestimated neurotic traits, there was a strong tendency of association: 61% of women were cat owners compared to 51.7% of the men (p = 0.051).
Table 2. The proportion of Cat and Dog owners in association to Personality and Gender presented in number and percentage, with Chi-2 statistics.
Note. Internal dropouts Extraversion = 79 and Neuroticism = 101; *p ≤ 0.05.
3.2. The Association between Personality and General Health Status in Cat and Dog Owners
The next step was to compare female and male owners of cats and dogs for self-reported general health status (not good/good) in relation to their personality. In Tables 3 and 4 women and men are separated.
Table 3. Cat and dog owners’ self reported General Health Status in relation to Extraversion and Gender.
Note. Internal dropouts = 185; *p ≤ 0.05.
Table 4. Cat and dog owners’ self reported general health in relation to Neuroticism and Gender.
Note. Internal dropouts = 208; *p ≤ 0.05.
When distributed by general health status and extraversion, it was shown that significantly more female cat owners were introverted; these women also reported poor health (65.1% of introverted women who were in poor health were cat owners compared with 54.0% of introverted women with good health). For men there were no such differences for introverts and extroverts, but when comparing not good/good health ratings there was a tendency (p = 0.055) for men who rated their health as not good to also be cat owners.
For women, the pattern of neuroticism was almost the same as for extraversion, namely less emotionally stable women (exhibiting high neuroticism) that rated their health as not good also reported a significantly higher percentage of cat ownership (64.8%) compared to the less emotionally stable female cat owners with good health (52.8%). There were no significant differences among neurotic men.
The shares of cat ownership among emotionally unstable women and men who reported a “not good” health status were, respectively, 64.8% versus 52.7% (p = 0.057). In all analyses, age was controlled for, but did not alter the results.
3.3. Predictions of Personality and Health on Pet Ownership
The final step was to examine whether current dog and cat ownership among older women and men could be predicted by personality and health. From the previous chi-squared statistic analyses interactions were constructed in the model. Since health could decrease with older age the interaction health and age was also added. Otherwise, age and gender were controlled for as separate variables.
Table 5 illustrates the result in the logistic regression model. Neither personality nor health could predict petownership. However, it was more likely for older individuals (80 - 101 years) to own a cat than a dog. This result did not change when the interactions were added. None of the included interactions were significant.