Abstract

The aim of this study is to estimate the prevalence of depression and its associated factors in elderly residents of the rural area of Rio Grande/RS. In this cross-sectional population-based study performed with 994 elderly (≥ 60 years), whose sampling was based on the 2010 Demographic Census, the Patient Health Questionnaire 9 (PHQ-9) was used for Major Depressive Episode (EDM) screening. Descriptive, bivariate and multivariate analyses were performed using logistic regression. The overall prevalence for Major Depressive Episode screening was 8.1%. The variables independently associated with depression were: female gender, continuous use of medications, chronic diseases, body mass index and worse health perception. The creation of programs target at the elderly in the rural area, aimed at screening, early diagnosis of depression and maintenance of treatment, encompassing several factors related to health, are important actions that must be fostered by the health system.

Key words
Depression; Elderly; Rural

Introduction

Depression is one of the most common mental disorders around the world, affecting about 350 million people¹1 World Health Organization (WHO). Mental Health and Older Adults Fact Sheet nº 381. Geneva: WHO; 2016.. It was the second largest cause of Years Lived with Disabilities (YLDs) in 2013, impairing 5% to 10% of the adult population at a global level²2 Becker A, Kleinman A. Mental Health and the Global Agenda. N Engl J Med 2013; 369(1):66-73.. During the aging process, changes such as the loss of loved ones³3 Ramos GCF, Carneiro JA, Barbosa ATF, Mendonça JMG, Caldeira AP. Prevalência de sintomas depressivos e fatores associados em idosos no norte de Minas Gerais: um estudo de base populacional. Jornal Brasileiro de Psiquiatria 2015; 64(2):122-131., the use of medications⁴4 Mohan Y, Jain T, Krishna S, Rajkumar A, Bonigi S. Elderly depression: unnoticed public health problem in India- a study on prevalence of depression and its associated factors among people above 60 years in a semi urban area in Chennai. International Journal of Community Medicine and Public Health 2017; 4(9):3468-3472. and the appearance of several diseases⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204. may impact the elderly’s mental health, increasing the susceptibility to depression³3 Ramos GCF, Carneiro JA, Barbosa ATF, Mendonça JMG, Caldeira AP. Prevalência de sintomas depressivos e fatores associados em idosos no norte de Minas Gerais: um estudo de base populacional. Jornal Brasileiro de Psiquiatria 2015; 64(2):122-131..

The prevalence of depression in the elderly varies between geographic regions, as well as between urban and rural centers. Population-based studies conducted in urban areas of different countries found prevalences of depressive symptoms ranging from 8% to 14%⁶6 Ferrari AJ, Somerville AJ, Baxter AJ, Norman R, Patten SB, Vos T, Whiteford HA. Global variation in the prevalence and incidence of major depressive disorder: a systematic review of the epidemiological literature. Psychol Med 2013; 43(3):471-481., while studies in rural areas found prevalences between 7.8%⁷7 Sengupta P, Benjamin AI. Prevalence of Depression and Associated Risk Factors among the Elderly in Urban and Rural Field Practice Areas of a Tertiary Care Institution in Ludhiana. Indian J Public Health 2016; 59(1):3-8. and 29.5%⁸8 Cardona D, Segura A, Segura A, Garzón MO. Efectos contextuales asociados a la variabilidad del riesgo de depresión en adultos mayores, Antioquia, Colombia, 2012. Biomédica 2015; 35(1):73-80.. The Pesquisa Nacional de Saúde (PNS)⁹9 Instituto Brasilerio de Geografia e Estatística (IBGE). Pesquisa Nacional de Saúde. Rio de Janeiro: Fiocruz; 2013., which evaluated populations living in urban and rural areas in Brazil found that 7.6% of individuals older than 18 years were diagnosed with depression, with a higher proportion in the 60-64 years age group (11.1%) and prevalence of 5.6% in rural adults. In addition, Munhoz et al.¹⁰10 Munhoz TN, Nunes BP, Wehrmeister FC, Santos IS, Matijasevich A. A nationwide population-based study of depression in Brazil. J Affect Disord 2016; 192:226-233. found a prevalence of 4.1% among Brazilian adults.

According to the World Health Organization¹1 World Health Organization (WHO). Mental Health and Older Adults Fact Sheet nº 381. Geneva: WHO; 2016., depression results from a complex interaction between social, psychological and biological factors. Several factors are associated with depression in the elderly. Research shown that female subjects⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204.^,1010 Munhoz TN, Nunes BP, Wehrmeister FC, Santos IS, Matijasevich A. A nationwide population-based study of depression in Brazil. J Affect Disord 2016; 192:226-233., with advanced age⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204.^,1111 Xinghu Zhou BB, Liqiang Zheng, Zhao Li, Hongmei Yang, Hongjie Song, Yingxian Sun. The Prevalence and Risk Factors for Depression Symptoms in a Rural Chinese Sample Population. PlosOne 2014; 9(6):1-8. and low schooling¹²12 Gao S, Jin Y, Unverzagt FW, Liang C, Hall KS, Ma F, Murrell JR, Cheng Y, Matesan J, Li P, Bian J, Hendrie HC. Correlates of depressive symptoms in rural elderly Chinese. Int J Geriatr Psychiatry 2009; 24(12):1358-1366.^,1313 Park JH, Kim KW, Kim M-H, Kim MD, Kim B-J, Kim S-K, Kim JL, Moon SW, Bae JN, Woo JI, Ryu S-W, Yoon JC, Lee N-J, Lee DW, Lee DW, Lee SB, Lee JJ, Lee J-Y, Lee C-U, Chang SM, Jhoo JH, Cho MJ. A nationwide survey on the prevalence and risk factors of late life depression in South Korea. J Affect Disord 2012; 138(1-2):34-40. were more likely to develop depression. Among behavioral factors, those most associated with the disorder are smoking¹⁴14 Munhoz TN, Santos IS, Matijasevich A. Major depressive episode among Brazilian adults: A cross-sectional population-based study. J Affect Disord 2013; 150(2):401-407.

15 An R, Xiang X. Smoking, heavy drinking, and depression among U.S. middle-aged and older adults. Prevent Med 2015; 81:295-302.^-1616 Gullich I, DuroI SMS, Cesar JA. Depressão entre idosos: um estudo de base populacional no Sul do Brasil. Revista Brasileira de Epidemiologia 2016; 19(4):691-701. and sedentary behavior¹⁷17 Santos D. Atividade física, comportamento sedentário e a sintomatologia depressiva em idosos. Uberaba: Universidade Federal do Triângulo Mineiro; 2013.^,1818 Pegorari MS, Dias FA, Santos NM, Tavares DM. Prática de atividade física no lazer entre idosos de área rural: condições de saúde e qualidade de vida. Journal of Physical Education 2015; 26:233-241.; among health-related characteristics, the most frequent are the presence of other chronic diseases¹⁹19 Abe Y, Fujise N, Fukunaga R, Nakagawa Y, Ikeda M. Comparisons of the prevalence of and risk factors for elderly depression between urban and rural populations in Japan. International Psychogeriatrics 2012; 24(8):1235-1241.^,2020 Behera P, Sharan P, Mishra AK, Nongkynrih B, Kant S, Gupta SK. Prevalence and determinants of depression among elderly persons in a rural community from northern India. The National Medical Journal of India 2016; 29(3):129-134., use of medications²¹21 Dutta M, Prashad L. Prevalence and risk factors of polypharmacy among elderly in India: Evidence from SAGE Data. International Journal of Public Mental Health And Neurosciences 2015; 2(2):11-16.^,2222 Wauters M, Elseviers M, Vaes B, Degryse J, Dalleur O, Stichele RV, Bortel LV, Azermai M. Polypharmacy in a Belgian cohort of community dwelling oldest old (80+). International Journal of Clinical and Laboratory Medicine 2016:1-9. and poor health perception³3 Ramos GCF, Carneiro JA, Barbosa ATF, Mendonça JMG, Caldeira AP. Prevalência de sintomas depressivos e fatores associados em idosos no norte de Minas Gerais: um estudo de base populacional. Jornal Brasileiro de Psiquiatria 2015; 64(2):122-131.^,2323 John PDS, Blandford AA, Strain LA. Does a rural residence predict the development of depressive symptoms in older adults? Can J Rural Med 2009; 14(4):150-156..

The world population is aging rapidly, the occurrence of depression at advanced ages is increasing and new health demands are emerging²⁴24 Duarte E, Barreto S. Transição demográfica e epidemiológica: a Epidemiologia e Serviços de Saúde revisita e atualiza o tema. Epidemiol Serv Saúde 2012; 21(4):529-532.. The study of elderly’s mental health is important to broaden the understanding of the disease-health process at this stage of development and to collaborate with public policies for this population²⁵25 Fleck MPA, Chachamovich E, Trentini CM. Projeto WHOQOL-OLD: método e resultados de grupos focais no Brasil. Rev Saúde Pública. 2003; 37(6):793-799.. The Brazilian studies that address the issue of depression in elderly residents of rural areas are scarce, since the great majority refers to urban areas⁶6 Ferrari AJ, Somerville AJ, Baxter AJ, Norman R, Patten SB, Vos T, Whiteford HA. Global variation in the prevalence and incidence of major depressive disorder: a systematic review of the epidemiological literature. Psychol Med 2013; 43(3):471-481., pointing out the need to develop Brazilian research on this subject in areas with lower population density²⁶26 Silva MT, Galvao TF, Martins SS, Pereira MG. Prevalence of depression morbidity among Brazilian adults: a systematic review and meta-analysis. Revista Brasileira de Psiquiatria. 2014; 36:262-270.. Thus, the present study aimed to estimate the prevalence of depression and its associated factors in elderly residents of the rural area of Rio Grande/RS.

Methods

Participants and sample process

Cross-sectional population-based study conducted in the rural area of Rio Grande, Rio Grande do Sul, Brazil, which was conducted between April and October 2017. This study was part of a larger study entitled Saúde da População Rural Rio Grandina, which evaluated the health of the elderly, children under 5 years and women at fertile age. The present study focused on the elderly population group. It is estimated that Rio Grande has 210,000 inhabitants, with about 4% of rural residents and approximately 13.1% of these are elderly residents - about 1,080 people aged 60 or over²⁷27 Instituto Brasileiro de Geografia e Estatística (IBGE). Censo Demográfico 2010. Rio de Janeiro: IBGE; 2011..

The inclusion criteria to participate in the study were: living in the rural area of the municipality of Rio Grande and being 60 years or older. All individuals institutionalized in nursing homes, hospitals and/or prisons were excluded, as well as those with physical and/or mental incapacity to respond to the interview.

Two sample size calculations were performed, one descriptive and other for associated factors. The parameters for the descriptive calculation were: prevalence of 10%, margin of error of 2p.p., level of significance of 5% and design effect of 1,5, resulting in 721 individuals. In the associated factors calculation, the parameters used were prevalence ratios of 1.5 to 2.0, power of 80%, level of significance of 5%, prevalence in non-exposed of at least 11%, ratio of not exposed to exposed of 5:1 and design effect of 1,5, resulting in 700 individuals. On top of the largest sample number, derived from the descriptive calculation (721), 10% were added to deal with losses and refusals and 15% to deal with confounding factors, obtaining a N of 901.

Sampling was based on the 2010 Demographic Census²⁷27 Instituto Brasileiro de Geografia e Estatística (IBGE). Censo Demográfico 2010. Rio de Janeiro: IBGE; 2011.. The sampling process consisted in the systematic selection of 80% of the households from the draw of a number between “1” and “5”. The number drawn corresponded to the residence considered hop. For example, if the number “3” was drawn, every household of number “3” in a sequence of five households was not sampled, that is, it was skipped. This procedure ensured that four out of five households were sampled. All the seniors were invited to participate in the study.

Data collection

Social, economic, demographic and behavioral questions were collected through the self-report of: sex; age (60-69 years, 70-79 years and 80 years or more); economic class collected according to the Associação Brasileira de Empresas de Pesquisa - ABEP, which estimates the purchasing power of Brazilian families²⁸28 Pesquisa ABE. Critério de classificação econômica Brasil Portal ABEP2014.; schooling (full years); marital status (with companion and without companion); use of alcohol in the last week; tobacco use; medication use, number of chronic noncommunicable diseases, body mass index (BMI) and health perception (very good/good, regular and poor/very poor). Questions regarding sedentary behavior were collected using the adapted Measure of Older Adults Sedentary Time (MOST) instrument, which verifies the individual’s sedentary behavior time in the last week through nine different situations, in hours or minutes per day²⁹29 Gardiner C, Healy E, Winkler O. Measuring older adults sedentary time: reliability, validity, and responsiveness. Med Sci Sports Exerc 2011; 43:2127-2133.. The variable was categorized into sedentary behavior less than 7 hours/day and more than 8 hours/day³⁰30 Ekelund U, Steene-Johannessen J, Brown WJ, Fagerland MW, Owen N, Powell KE, Bauman A, Lee IM, Lancet Physical Activity Series Executive Committe; Lancet Sedentary Behaviour Working Group Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Lancet 2016; 388(10051):1302-1310..

The outcome, presence or absence of depression, was identified through Major Depressive Episode (MDE) screening using the Patient Health Questionnaire-9 (PHQ-9) instrument, which assesses the presence of depressive symptoms in the last two weeks, based in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V)³¹31 American Psychological Association (APA). Diagnostic and Statistical Manual of Mental disorders: DSM-5. Washington: APA; 2013.. The recommended cutoff point is ≥ 9, which has good psychometric and operational characteristics, with sensitivity between 77 and 98% and specificity of 75-80%³²32 Santos IS, Tavares BF, Munhoz TN, Almeida LSP, Silva NTB, Tams BD, Patella Am, Matijasevich A. Sensibilidade e especificidade do Patient Health Questionnaire-9 (PHQ-9) entre adultos da população geral. Cad Saude Publica 2013; 29(8):1533-1543..

The questionnaires were applied through tablets by previously selected and trained interviewers using the RedCap® program³³33 Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap)-A metadata-driven methodology and workflow process for providing translational research informatics support. Journal of Biomedical Informatics. 2009; 42(2):377-381.. Prior to data collection, a pilot study was conducted in one of the census tracts near the city to verify and correct problems in interpreting questions and timing the questionnaire application time.

Data analysis

Statistical analyses were performed on software Stata IC 13.1 (Stata Corp., College Station, USA). Univariate analysis was conducted to describe the sample in terms of independent variables and also to calculate the prevalence of depression in the population. Bivariate analysis was also performed using the chi-square test for categorical variables and Student’s t-test or Wilcoxon Mann-Whitney test for numerical variables (depending on the data distribution). Adjusted analysis was performed through logistic regression using the presence or absence of Major Depressive Episode as an outcome. Logistic regression was performed considering the hierarchical analysis model (Figure 1)³⁴34 Victora CG, Huttly SR, Fuchs SC, Olinto MTA. The role of conceptual frameworks in epidemiological analysis: a hierarchical approach. Int J Epidemiol 1997; 96(1):224-227. constructed for the present study, using the backward selection process and considered p value ≤ 0.20 to keep the variables in the model. The level of significance for all analyses was 5%. This study was approved by the Comitê de Ética em Pesquisas na Área da Saúde (CEPAS) of FURG. Participation was voluntary and individuals who accepted participation were asked to sign a free and informed consent form.

Results

The study had a total of 1,130 eligible individuals and 1,030 elderly interviewed, corresponding to a rate of losses and refusals of 8.9%. 994 elderly people in the rural area of Rio Grande responded to PHQ-9 completely, resulting in 10.1% of losses, 1.9% of refusals and a response rate of 88%. The overall prevalence for Major Depressive Episode screening was 8.1%.

Table 1 shows that the sample consisted mostly of male individuals (55.5%), aged between 60 and 69 years (52.5%) and with a companion (63.2%). Half of the individuals were in economy class C (51.9%) and the schooling median was 3 years (IIQ = 1 - 5). Approximately four-fifths of the sample reported the non-use of alcohol in the last week (82.9%), while more than half reported being non-smoker (52.7%) and perceived health as very good or good (58, 0%). 75.6% of the sample reported continuous medication use and 39.1% reported having more than two chronic diseases. In addition, the majority had a sedentary behavior duration of less than 7 hours per day (87.9%), and the mean BMI was 26.5kg/m² (SD = ± 4.7).

From Table 1, it is possible to observe that the prevalence of depression was higher in female subjects (10.4%) and in continuous medication users (10.3%). Those with poor or very poor health perception had a prevalence of 35.2%, almost five times higher than the general (8.1%). Those who had two or more chronic diseases had a prevalence of 13%, and the mean BMI of individuals with depression was 26.2kg/m², while the mean of those without depression was 26.5kg/m².

Table 2 presents the results from the adjusted analysis for depression. After adjusted analysis, the variables gender, medication use, chronic diseases, BMI and health perception remained associated with the outcome. Thus, the chance of developing depression was higher in female subjects (OR = 1.65, 95%CI = 1.04 - 2.62) and medication users (OR = 5.16, 95%CI = 1.74 - 15,33). In addition, those who perceived their health as poor or very poor presented almost twenty times more chances for the disorder when compared to individuals who considered their health very good/good (OR = 19.6, 95%CI = 8.65-44, 32). It was also observed that the chance of developing depression decreases by 6% in each increased kg/m² in the BMI (p = 0.04), and there was a trend between the number of chronic noncommunicable diseases and the chance of developing the disorder (OR = 2.4, 95%CI = 1.11-5.19).

Discussion

This study identified that 8.1% of the elderly in the rural area of Rio Grande (RS) fulfilled the criteria for screening for Major Depressive Episode. The variables gender, continuous medication use, chronic diseases and health perception remained associated after adjusting for potential confounders. In addition, was observed a protection effect at each increase of one kg/m² in body mass index.

The prevalence of depression found in the study (8.1%) was lower when compared to a study carried out with rural elderly in Brazil⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204. and with elderly residents of rural areas from other countries⁸8 Cardona D, Segura A, Segura A, Garzón MO. Efectos contextuales asociados a la variabilidad del riesgo de depresión en adultos mayores, Antioquia, Colombia, 2012. Biomédica 2015; 35(1):73-80.^,3535 Fukunaga R, Abe Y, Nakagawa Y, Koyama A, Fujise N, Ikeda M. Living alone is associated with depression among the elderly in a rural community in Japan. Psychogeriatrics 2012; 12(3):179-185.. A study carried out in Pelotas with elderly residents from the urban area also presented a higher prevalence (15.2%)³⁶36 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584.. However, the prevalence found in the present study was higher than the one found by the PNS⁹9 Instituto Brasilerio de Geografia e Estatística (IBGE). Pesquisa Nacional de Saúde. Rio de Janeiro: Fiocruz; 2013., which investigated adults living in rural areas (5.6%). The result found was also higher when compared to the study by Munhoz et al.¹⁰10 Munhoz TN, Nunes BP, Wehrmeister FC, Santos IS, Matijasevich A. A nationwide population-based study of depression in Brazil. J Affect Disord 2016; 192:226-233., which found a prevalence of 4.1% among adults in southern Brazil; among the elderly in the southern region, prevalence varied between 5.5% (60-69 years) and 6% (80 years or more). PNS⁹9 Instituto Brasilerio de Geografia e Estatística (IBGE). Pesquisa Nacional de Saúde. Rio de Janeiro: Fiocruz; 2013. also found the highest percentage of adults diagnosed with depression in the southern region of Brazil (12.6%). The differences found in prevalence rates may be due the use of different scales to evaluate depression. The correction using the cut-off point of PHQ-9 has sensitivity between 77 and 98%, and specificity of 75 to 80%, favoring the sensitivity of the test³²32 Santos IS, Tavares BF, Munhoz TN, Almeida LSP, Silva NTB, Tams BD, Patella Am, Matijasevich A. Sensibilidade e especificidade do Patient Health Questionnaire-9 (PHQ-9) entre adultos da população geral. Cad Saude Publica 2013; 29(8):1533-1543., whereas the Geriatric Depression Scale, used in the majority of studies with elderly, is applied using a smaller cut-off point (≥ 6), being less sensitive when compared to PHQ-9⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204.^,88 Cardona D, Segura A, Segura A, Garzón MO. Efectos contextuales asociados a la variabilidad del riesgo de depresión en adultos mayores, Antioquia, Colombia, 2012. Biomédica 2015; 35(1):73-80.^,3535 Fukunaga R, Abe Y, Nakagawa Y, Koyama A, Fujise N, Ikeda M. Living alone is associated with depression among the elderly in a rural community in Japan. Psychogeriatrics 2012; 12(3):179-185..

Regarding the association between MDE and gender, the chance of developing depression was greater among women. This finding is recurrent in the literature: studies conducted in rural areas of Canada³⁷37 John PDS, Blandford AA, Strain LA. Depressive symptoms among older adults in urban and rural areas. Int J Geriatr Psychiatry 2006; 21(12):1175-1180. and India⁷7 Sengupta P, Benjamin AI. Prevalence of Depression and Associated Risk Factors among the Elderly in Urban and Rural Field Practice Areas of a Tertiary Care Institution in Ludhiana. Indian J Public Health 2016; 59(1):3-8. with seniors goes in the same direction, presenting the female sex as a risk factor for the development of depressive disorder. In Greece, however, no differences were found in depression levels between men and women³⁸38 Papadopoulos FC, Petridou E, Argyropoulou S, Kontaxakis F, Dessypris V, Anastasiou A, Katsiardani KP, Trichopoulos D, Lyketsos C. Prevalence and correlates of depression in late life: a population based study from a rural Greek town. Int J Geriatr Psychiatry 2005; 20(4):350-357.. Brazilian studies performed with elderly populations corroborate with international data, finding a higher prevalence of depression among women⁵5 Ferreira PCS, Tavares DMS, Martins NPF, Rodrigues LR, Ferreira LA. Características sociodemográficas e hábitos de vida de idosos com e sem indicativo de depressão. Rev Eletr Enf 2013; 15(1):197-204.^,3636 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584.^,3939 Rodrigues LR, Tavares DM, Silveira FB, Dias FA, Martins NP. Qualidade de vida, indicativo de depressão e número de morbidades de idosos da zona rural. Revista de Enfermagem e Atenção à Saúde 2016; 4(2):278-285.. It is possible that women are more susceptible to the development of depression due to social and biological factors, such as greater sensitivity to potentially stressors events¹⁰10 Munhoz TN, Nunes BP, Wehrmeister FC, Santos IS, Matijasevich A. A nationwide population-based study of depression in Brazil. J Affect Disord 2016; 192:226-233.^,3636 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584. and estrogen deprivation, which may influence the occurrence of depression⁴⁰40 Almeida OP. Idosos atendidos em serviço de emergência de saúde mental: características demográficas e clínicas. Rev Bras Psiquiatr 1999; 21(1):8-12..

Older people who reported continuous medication use were five times more likely to develop depression. The greater consumption of drugs in this phase of life, often due to the coexistence of several diseases, can have side effects and a negative perception of health, as well as a decline in the metabolism of pharmaceutical substances⁴¹41 Taylor WD. Depression in the Elderly. N Engl J Med 2014; 371(13):1228-1236.. The use of several drugs at the same time, also known as polypharmacy, is common during aging and may have negative consequences due to pharmacokinetic and pharmacodynamic changes inherent in the elderly⁴²42 Secoli SR. Polifarmácia: interações e reações adversas no uso de medicamentos por idosos. Revista Brasileira de Enfermagem 2010; 63(1):136-140.. Longitudinal studies conducted in Belgium²²22 Wauters M, Elseviers M, Vaes B, Degryse J, Dalleur O, Stichele RV, Bortel LV, Azermai M. Polypharmacy in a Belgian cohort of community dwelling oldest old (80+). International Journal of Clinical and Laboratory Medicine 2016:1-9. and in India²¹21 Dutta M, Prashad L. Prevalence and risk factors of polypharmacy among elderly in India: Evidence from SAGE Data. International Journal of Public Mental Health And Neurosciences 2015; 2(2):11-16. with elderly residents of urban areas have found that the diagnosis of depression is significantly associated with the use of several drugs, contributing to the occurrence of polypharmacy. This phenomenon is also associated with both patients’ and health system’s significant increase in health expenditures⁴³43 Maher R, Hanlon J, Hajjar E. Clinical consequences of polypharmacy in elderly. Expert Opinion Drug Saf 2014; 13(1):57-61..

Elderly with two or more chronic diseases were twice as likely to present depression. This finding is recurrent in studies carried out with elderly populations in rural areas, where a positive association between morbidities and depressive symptomatology was found¹⁹19 Abe Y, Fujise N, Fukunaga R, Nakagawa Y, Ikeda M. Comparisons of the prevalence of and risk factors for elderly depression between urban and rural populations in Japan. International Psychogeriatrics 2012; 24(8):1235-1241.^,2020 Behera P, Sharan P, Mishra AK, Nongkynrih B, Kant S, Gupta SK. Prevalence and determinants of depression among elderly persons in a rural community from northern India. The National Medical Journal of India 2016; 29(3):129-134.^,4444 Peltzer K, Phaswana-Mafuya N. Depression and associated factors in older adults in South Africa. Global Health Action 2013; 6:1-9.. However, studies conducted in Brazil with elderly people from urban and rural regions found no association between depression and such variable³⁶36 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584.^,4545 Borges LJ, Benedetti TRB, Xavier AJ, d'OrsiI E. Fatores associados aos sintomas depressivos em idosos: estudo Epi Floripa. Rev Saude Publica 2013; 47(4):701-710.. Individuals who have chronic diseases are more likely to develop depression than those without other diseases, so the coexistence of these two conditions is very common⁴⁴44 Peltzer K, Phaswana-Mafuya N. Depression and associated factors in older adults in South Africa. Global Health Action 2013; 6:1-9.. Moreover, the relationship between depression and chronic diseases can be two-way, since problems such as chronic pain may lead to a predisposition to depression, so depressive symptoms are associated with negative health outcomes such as heart disease⁴¹41 Taylor WD. Depression in the Elderly. N Engl J Med 2014; 371(13):1228-1236..

There was an association between body mass index and depression in the adjusted analysis. Significant association between BMI and depression was observed in studies with elderly populations in Japan, Colombia and United States⁸8 Cardona D, Segura A, Segura A, Garzón MO. Efectos contextuales asociados a la variabilidad del riesgo de depresión en adultos mayores, Antioquia, Colombia, 2012. Biomédica 2015; 35(1):73-80.^,1515 An R, Xiang X. Smoking, heavy drinking, and depression among U.S. middle-aged and older adults. Prevent Med 2015; 81:295-302.^,4646 Yoshimura K, Yamada M, Kajiwara Y, Nishiguchi S, Aoyama T. Relationship between depression and risk of malnutrition among community-dwelling young-old and old-old elderly people. Aging Ment Health 2013; 17(4):456-460.. However, studies with elderly populations in Brazilian urban areas⁴⁵45 Borges LJ, Benedetti TRB, Xavier AJ, d'OrsiI E. Fatores associados aos sintomas depressivos em idosos: estudo Epi Floripa. Rev Saude Publica 2013; 47(4):701-710. and in rural areas in Japan¹²12 Gao S, Jin Y, Unverzagt FW, Liang C, Hall KS, Ma F, Murrell JR, Cheng Y, Matesan J, Li P, Bian J, Hendrie HC. Correlates of depressive symptoms in rural elderly Chinese. Int J Geriatr Psychiatry 2009; 24(12):1358-1366. did not find an association between the variables. Changes in weight and appetite are symptoms of depression; in this sense such association should be checked with caution because of possible bidirectionality. Loss of weight and appetite are recurrent aspects of old age due to biological alterations from this phase of life⁴⁷47 Tamura BK, Bell CL, Masaki KH, Amella EJ. Factors Associated With Weight Loss, Low BMI, and Malnutrition Among Nursing Home Patients: A Systematic Review of the Literature. JAMDA 2013; 14(9):649-655. and depression may be one of the causes of BMI change and, at the same time, a consequent associated factor⁴⁶46 Yoshimura K, Yamada M, Kajiwara Y, Nishiguchi S, Aoyama T. Relationship between depression and risk of malnutrition among community-dwelling young-old and old-old elderly people. Aging Ment Health 2013; 17(4):456-460..

An inverse trend was observed between development of depression and health perception among the interviewed elderly. Those who considered their health poor or very poor were twenty times more likely to develop depression compared to the reference group. This finding is consistent with studies carried out with rural elderly populations in the world²³23 John PDS, Blandford AA, Strain LA. Does a rural residence predict the development of depressive symptoms in older adults? Can J Rural Med 2009; 14(4):150-156.^,4848 Alpass FM, Neville S. Loneliness, health and depression in older males. Aging & Ment Health 2003; 7(3):212-216. and in Brazil³3 Ramos GCF, Carneiro JA, Barbosa ATF, Mendonça JMG, Caldeira AP. Prevalência de sintomas depressivos e fatores associados em idosos no norte de Minas Gerais: um estudo de base populacional. Jornal Brasileiro de Psiquiatria 2015; 64(2):122-131.^,3636 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584.^,4545 Borges LJ, Benedetti TRB, Xavier AJ, d'OrsiI E. Fatores associados aos sintomas depressivos em idosos: estudo Epi Floripa. Rev Saude Publica 2013; 47(4):701-710.. In this lifetime age, the increase in medication consumption and chronic diseases³⁶36 Hellwig N, Munhoz TN, Tomasi E. Sintomas depressivos em idosos: estudo transversal de base populacional. Cien Saude Colet 2016; 21(11):3575-3584., along with a decrease in work, less interaction with others and feelings of disability influence a worse perception of health and the occurrence of depressive symptoms⁴⁹49 Castro-Costa E, Lima-Costa MF, Carvalhais S, Firmo JOA, Uchoa E. Factors associated with depressive symptoms measured by the 12-item General Health Questionnaire in Community-Dwelling Older Adults (The Bambuí Health Aging Study). Revista Brasileira de Psiquiatria 2008; 30(2):104-109.. In other words, this association may represent a bidirectionality relationship.

The associations found in the present study and the lack of association in certain variables can be explained in part by differences between elderly people living in rural and urban areas. Studies that sought to compare the prevalence of depression in rural and urban areas found that reside in rural areas is considered a protective factor against the development of chronic non-communicable diseases²³23 John PDS, Blandford AA, Strain LA. Does a rural residence predict the development of depressive symptoms in older adults? Can J Rural Med 2009; 14(4):150-156. because elderly residents from urban areas are exposed to factors that may contribute to the development of health issues, such as fewer hours of sleep and worse quality of life⁷7 Sengupta P, Benjamin AI. Prevalence of Depression and Associated Risk Factors among the Elderly in Urban and Rural Field Practice Areas of a Tertiary Care Institution in Ludhiana. Indian J Public Health 2016; 59(1):3-8.; in addition, the natural environment, characteristic of the rural area, is responsible for reducing stress levels⁵⁰50 Helbich M. Toward dynamic urban environmental exposure assessments in mentalhealth research. Environ Res 2018; 161:129-135.. Study in Canadá³⁷37 John PDS, Blandford AA, Strain LA. Depressive symptoms among older adults in urban and rural areas. Int J Geriatr Psychiatry 2006; 21(12):1175-1180., which sought to compare the prevalence of depression among rural and urban areas, found a higher prevalence of depression among elderly residents of urban areas, compared to those living in predominantly rural areas (11.6% and 9%, respectively); furthermore, a comparative study developed in Japan found that the risk factors for each population differed, with less occurrence of depression in rural areas¹⁹19 Abe Y, Fujise N, Fukunaga R, Nakagawa Y, Ikeda M. Comparisons of the prevalence of and risk factors for elderly depression between urban and rural populations in Japan. International Psychogeriatrics 2012; 24(8):1235-1241..

A country can present regional differences regarding culture, social and economic conditions, which may result in certain disparities⁵¹51 Breslau J, Marshall G, Pincus H, Brown R. Are mental disorders more common in urban than rural areas of the United States? J Psychiatr Res 2014; 56:50-55.. Residents of rural areas may present greater health challenges, both due to difficulties in accessing services and income related issues, so that the factors associated with depression in this context point to general health characteristics⁵²52 Probst J, Laditka S, Moore C, Harun N, Powell P, Baxley E. Rural-Urban Differences in Depression Prevalence: Implications for Family Medicine. Fam Med 2006; 38(9):653-660.. Environmental and socio-cultural issues should also be taken into account, since the mental health of the individual is modeled by the socio-environmental context in which he is inserted, so that the environment itself may increase the risk for the development of a mental disorder⁵⁰50 Helbich M. Toward dynamic urban environmental exposure assessments in mentalhealth research. Environ Res 2018; 161:129-135.. Regarding mental disorders, residents from rural areas are less likely to report the need for treatment, care for the problem and the very existence of mental health problems, when compared to residents from urban areas⁵³53 Romans S, Cohen M, Forte T. Rates of depression and anxiety in urban and rural Canada. Soc Psychiatry Psychiatr Epidemiol 2011; 46(7):567-575..

The cross-sectional design was adequate to respond the main question of this research. However, the possible reverse causality, inherent to cross-sectional studies, should be considered as one of the study’s limitation. Moreover, it is possible that the prevalence of depression is underestimated by those individuals who did not respond to PHQ-9 completely and were excluded from the sample. It is important to emphasize that, although PHQ-9 is useful for the disorders screening, it does not replace the diagnosis based on a clinical interview conducted by psychologists and psychiatrists. Thus, regardless of how the instrument is used, the result should be described as a probable diagnosis of MDE.

Among the study’s advantages it should be emphasized that this is a population-based study, conducted through a household survey and with a low percentage of losses and refusals when compared to other surveys. In addition, despite several publications about depression in Brazil, few were found addressing the issue in rural regions. Regarding the instrument used for MDE screening, the present study used a validated instrument for the Brazilian population, which has been used in other countries³²32 Santos IS, Tavares BF, Munhoz TN, Almeida LSP, Silva NTB, Tams BD, Patella Am, Matijasevich A. Sensibilidade e especificidade do Patient Health Questionnaire-9 (PHQ-9) entre adultos da população geral. Cad Saude Publica 2013; 29(8):1533-1543..

Female elderly, with lower BMI, users of continuous medications, with two or more chronic illnesses and with worse health perception were more likely to have depressive symptomatology. In other words, they are more exposed to the negative effects of depression. The research carried out in the present study is fundamental to understand the peculiarity of the rural space, considering that there is a shortage of studies on the depression subject in rural areas. Thus, our findings highlight the need to implement policies that consider health in a broad way, since several aspects can contribute to the development of mental health problems. Programs’ designed targeting elderly in rural areas, screening, early diagnosis of depression and maintenance of treatment, encompassing several factors related to health, are important actions that must be fostered by the health system.

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