INTRODUCTION

Aging is influenced not only by biopsychosocial changes, but also by other multidimensional contexts, such as financial status, lifestyle, personal achievement, illnesses, accumulated suffering, and genetic factors.¹

The concept of depression includes the presence of affective, cognitive, volitional, and somatic symptoms that mainly affect the emotional domain.^2,3 Depression manifests in the older adult population in various ways: as a recurring illness from before old age, recent onset as a mental disorder secondary to a general medical condition, or as a secondary symptom associated by the use of medications. Similar to what occurs in other age groups, depression probably stems from a complex multidirectional interaction of biological, psychological (including personality), and social factors.⁴ A diagnosis of depression is based on observed data and the symptoms reported by patients, based on the International Statistical Classification of Diseases and Related Health Problems (ICD) and the American Psychiatric Association (DSM) criteria. Even though several population-based studies identify depression symptoms using screening scales, the Center for Epidemiological Studies Depression Scale (CES-D)^5,6 is the most used instrument.

Depression in older adults is a major health issue and is considered the most common psychiatric disorder among this population in developed countries, associated with suffering and increased prevalence and poor evolution of health problems.⁷ The prevalence of depression in older adults is 13.5% worldwide.⁸ However, in a European study carried out with community-dwelling older adults, this percentage was 12.3%,⁹ whereas in Spain, it was 14%.¹⁰ The prevalence of major depression (recurrent episodes) in community-dwelling older adults is between 1 and 5%.¹¹

Some factors specific to depression in older adults have been identified, such as comorbidity, neurological disorders, psychosocial factors, social support, and life stressors.¹² Learning more about the factors associated with this pathology can help outline actions that aim to improve the health of older adults.

The objective of this study was to determine the prevalence of depression and factors associated with older adults over the age of 75 years in the city of Castellón de la Plana, Spain.

METHODOLOGY

RESULTS

A total of 400 individuals were interviewed, with a mean age of 81.29 ranging from 75 to 96 years of age, of which 46.8% were male and 53.2% were female.

Descriptive analysis by gender (^{Table 1}) showed that 30.5% of the individuals presented depression symptoms, with women presenting higher rates (40.1%) than men (19.7%). Most 78.2% individuals had partners, but among women, this percentage was lower (68.7%) than men (88.9%). Regarding level of education, 51.8% of the individuals did not have a high school education.

In terms of income, 41.5% of the older adults earned less than 900 euros monthly, and among women this rate was higher.

Self-perceived health was considered good by 62.9% of the sample. Women perceived their general health as good less often than men: 55.5% compared with 71.4%.

On comparing frailty by gender, 23.2% of the sample self-reported as frail, wherein women presented higher rates than men: 28% compared with 18%.

Table 1. Sample characteristics by gender: count (n) and percentage (%) 

^{Note: *}NDue to the level of nonresponse for this variable (see Demaio 1980), the inferred values may not represent the population’s characteristics.

Bivariate analysis of the association of depression symptoms with the studied variables (Table ²), showed that, in terms of age, there were no statistically significant differences between individuals under the age of 85 years and 85 years old or older.

Statistically significant differences (p=0.011) were found related to living conditions: older adults living alone showed more depression symptoms than those living with a partner: 26.6% compared with 16.1%.

Table 2. Depression symptoms according to study variables: count (n) and percentage (%) 

^{Note: *}Due to the level of no answer for this variable (see Demaio 1980) the inferred values may not be representative of the population characteristics.

No statistically significant differences were found between the presence of depression symptoms and monthly income; the same was true for level of education.

Conversely, regarding self-perceived health, individuals who self-reported good health conditions did not present depression symptoms at higher rates (75.1%) than those who perceived their health as poor (24.9%) (p=0.000).

Regarding frailty, non-frail individuals presented less depression symptoms (12.1%) than intermediate (57%) and frail individuals (30.8%) (p=0.000).

An analysis of the participants’ social relationships (^{Table 3}) shows that there were no significant differences in the rates of family ties, community activities, network diversity, and received emotional support; however, mean scores were lower among individuals who presented more depression symptoms. Considering only the negative aspects of social relationships, the mean score was significantly (p=0.006) higher among individuals with depression symptoms.

Table 3. Depression symptoms according to the social relationships: count (n) y rate (%) 

As for binary logistic regression analysis, which assessed the possibility of presenting depression (^{Table 4}), the variables that presented statistical significance in bivariate analysis were introduced one by one: gender, living condition, frailty, self-perceived health, and negative aspects of social relationships. Gender (female) was statistically significant in the three models, with women presenting almost double the risk of men of being affected by depression (OR: 1.953; CI: 1.159-3.292). Additionally, living condition also presented a significant association with depression: Individuals living with partners showed lower risk of suffering depression symptoms (OR: 0.429; CI: 0.239-0.771). Negative self-perceived health was associated with a higher risk of presenting depression symptoms (OR: 2.582; CI: 1.552-4.295). Frailty was positively associated with depression symptoms, in which frail older adults presented twice the risk of suffering from depression symptoms (OR: 2.118; CI: 1.430-3.136). There was no link between the negative aspects of social relationships and depression symptoms.

Table 4. Odds Ratio (OR) and 95% confidence interval (95%CI) of the binary logistic regression model that assesses the possibility of presenting depression symptoms 

DISCUSSION

The prevalence of depression estimated in different studies varies considerably. The Figures obtained in the current work (30.5%) are very similar to those presented in the study conducted in Lleida¹⁸ applying the same methodology. However, the results are lower than those obtained in the works of Sánchez-García et al ¹⁹ and Estrada et al.²⁰, which used the CES-D-R (modified CES-D scoring) as a measuring tool (56.8% and 47.6% respectively). This may be because the modified CES-D scoring method has proved to be more sensitive in identifying depression symptoms among the older adult population.¹⁹Variability in the prevalence of depression may be due to the fact that the researchers did not perform a screening test first, followed by diagnostic confirmation.²¹

In the current study, differences between gender were observed with more depression symptoms occurring in women, data that coincide with the findings of other studies,^18,19,22 and can be related to social and cultural factors. In contrast, some authors claim that differences in the prevalence of depression between men and women decrease with age, as shown by a study by Urbina et al.²³.

Regarding age, no significant differences were found in the Castellón sample, in contrast to the findings of studies with populations of Valle (Mexico), and Moscow.^7,19,24 A possible explanation is that there were very few older adults 85 years old or older in the Castellón sample.

Regarding living condition, significant differences were observed among older adults living alone, who presented more symptoms of depression. This agrees with the studies of Zavala-González⁷, Domínguez-Sosa²⁵, Escobar et al.¹⁸ and Ferreira & Tavares.²⁶ Contrary to the results of the present study, Acosta & García²⁷ found no significant differences in terms of living conditions, perhaps because they included a broader age group.

The perceived monthly income was not related with depression symptoms, although these results may be taken with caution, since the percentage of losses in the question is high, especially taking into account that, in the consulted literature, a relationship between the economic factor and depression was observed.^7,18

Positive self-perceived health was associated with lower prevalence of depression,²⁰ in agreement with the results of the current study. Considering that positive health perception is linked to a better physical health condition, the present results are in accordance with those obtained by Escobar et al,¹⁸ and Kronfly Carlos-Gil et al.²⁸

Differences were found in the frailty of participants, in that the frail and intermediate individuals were associated with the presence of depression symptoms, a finding that coincides with the works of Díaz de León et al²⁹ and Carlos-Gil et al.³⁰ This relationship may be explained by the increased vulnerability of frail and intermediate older adults when faced with stressful situations.³¹

Regarding social relationships among the Castellón population, significant differences were found regarding negative perceptions of their friends and family ties. The results are in accordance with those of Ferlander et al.²⁴ and Marroquin & Nolen-Hoeksema.³² Along the same lines, Zavala et al.⁷ described a link between poor family ties and higher risk of depression. However, in the current study, this variable did not present predictive value.

The results of the present study confirm that being a woman, having positive self-perceived health, and frailty were strongly associated with the presence of symptoms of depression, similar to other studies.^33,34 The negative aspects of social relationships did not present a significant association, even though it is presented by the literature as a predictor variable,^35,36 and this can be an effect of the good family support networks presented by the sample of the current study.

Limitations of the present study include data loss from the participants who presented cognitive impairments and did not answer the survey’s subjective questions. Furthermore, purposive sampling is subject to the willingness of the healthcare centers to participate in the study and may have impacted the results. Last, the cross-sectional design of this work prevents the researchers from establishing casual relationships.

CONCLUSIONS

The results point to a relationship between the presence of depression symptoms and the female gender, negative self-perceived health, frailty, and living alone, in agreement with most of the bivariate analysis results.

The prevalence of depression symptoms was high. Related factors were gender, with higher rates among women; living condition, with higher rates among older adults living alone; and frailty.

The high prevalence of depression symptoms in the study population justifies the need to design interventions aimed at this issue. Efficient actions should focus on aspects associated with the presence of depression symptoms and propose new lines of longitudinal studies.