Depression and obesity are two conditions with great impact over global health. This is mainly due to their high prevalence and the morbidity and mortality associated to both. The main aim of the present systematic review is to study the association between obesity and depression and the prognostic implications derived from it.
A literature review was performed in the PUBMED database. 18 articles were found (9 cross-sectional studies, 6 longitudinal studies and 3 clinical trials), which were reviewed by critical reading after which a summary of the main conclusions was written.
These selected articles confirmed that there is indeed a link between depression and obesity, although there are doubts as to the significance of this relationship. Depression is a risk factor for obesity, especially atypical depression and in African-American adolescent males. Obesity is a risk factor for depression, especially in women and for recurrent depressive disorder. The comorbidity between obesity and depression is a risk factor for a bad prognosis illness.
The relationship between both disorders has been analysed in scientific literature, obtaining significant associations but also contradictory results. The most current data demonstrates that there is a relationship between both entities, although there is no unanimity when it comes to establishing the meaning of this association.
Obesity and depression are considered notorious health problems, not only because of their significant prevalence but also because of their high morbidity mortality rates. According to recent data from the World Health Organization (WHO) in 2014 it was estimated that more than 600 million people were affected with obesity whilst at least 2.6 million people die from obesity every year. 44% of global cases of diabetes, 23% of ischemic heart diseases and 7–41% of certain cancers are attributable to overweight and obesity [
The probable association between obesity and depression has been studied repeatedly over time in scientific literature. This is mainly due to the fact that they both carry a high prevalence and an increased risk of cardiovascular disease [
Prospective studies have revealed inconsistent findings regarding the sequence in the onset of depression and obesity [
The main objectives of this review will be three; 1) to define the methodological quality of those more recent studies that analysed the association between depression and obesity, 2) to determine whether there is indeed an association between both conditions and 3) to clarify what influence they may have over each other. Additionally it will examine the importance of certain socio-demographic, clinical and therapeutic variables in the relation between obesity and depression.
A literature review was conducted of those articles published in the PUBMED database with an inclusion deadline from January 1, 2012 to December 31, 2017, using the following MeSH terms: “obesity” AND “depressive disorder.” The filters applied were those of studies published in the last 6 years and carried out in humans. 179 articles were obtained and the main researcher (BV) made an exhaustive reading of the abstracts, selected the publications based on the inclusion criteria and was responsible for the successive stages. We follow the international recommendations for systematic reviews as Preferred Items for Reporting of Systematic Reviews and Meta-Analyses (PRISMA) [
The following inclusion criteria was applied: available abstract, English written articles, already established diagnostic criteria for both conditions (obesity according to body mass index (BMI) and depression according to major depression criteria in the DSM IV or ICD-10, studies of prevalence in both pathologies and finally, the evaluation of the possible prognostic association between these conditions when they affect the same person simultaneously. The exclusion criteria where the following: no available abstract, articles written in a non-English language, articles of very low quality according to the GRADE system (Grading of Recommendations, Assessment, Development and Evaluation) [
The GRADE system initially classifies the evidence into high or low, coming from experimental or observational studies; subsequently and following a series of considerations (risk/benefit balance, values and preferences of the patients and professionals, and the use of resources or costs), the evidence is classified into high, moderate, low or very low [
By reading the abstracts, a total of 39 articles were selected, which were then thoroughly revised, eventually discarding 21 of them for not complying with the inclusion criteria. Most of these articles were discarded for failing to adapt to the international diagnostic standards rendering it difficult to draw clear conclusions. The third stage corresponded to the critical reading of the 18 selected articles.
Of the 18 selected studies, 15 were observational and 3 were experimental clinical trials. Within the observational group (15), 6 had a longitudinal design (one retrospective and five prospective) and the other 9 were cross-sectional. The main features as well as the evaluation of the quality of these studies are summarized in
Methodological quality of the studies (
In this section we will focus on those 10 studies that studied depression as a risk factor for obesity. The conclusions here obtained were not uniform. Three of these studies [
Another study focused on age and ethnicity [
In this second section, we discovered 5 studies that concluded that obesity was a risk factor for depression. Only one of the articles could not establish a relationship between both disorders, although the conclusions must be adjusted [
An overall of four articles viewed this subject. The first article [
Our chief aim when undertaking this systematic review has been to clarify the association between obesity and depression, two diseases with great impact over global health. In none of the three sections in which the selected articles have been divided (depression>risk factor>obesity, obesity>risk factor> depression and prognosis when depression and obesity are associated) have we observed unanimity in the conclusions.
In the first group (depression as risk factor for obesity) 8 out of the 11 selected articles presented data in favour of this association. We highlight the results of a clinical trial [
We also analysed articles that could not demonstrate a correlation between obesity and depression [
In the second section there is a greater consensus when it comes to affirming that obesity increases the risk of depression. Out of the six selected articles, five concluded that there is an association between both factors. Once again, the depressive subtype, the average age of the sample and sex are variables that influenced the results. For example, according to Nigatu et al. [
In the third section we analysed the influence on the prognosis of the obesity-depression combination in the same patient. We found two clinical trials [
It has been suggested that the association between depression and obesity is probably due to the action of certain genes involved in both pathologies. For example the genes that encode glucocorticoids, leptin and dopamine receptors. The role of environmental factors should also be noted, especially all those situations that contribute to maintaining a situation of chronic stress. The results of a study conducted on twins by Afari et al. [
As previously explained, the wide methodological variety of the studies included in this review hampered the conclusion of unequivocal results. This is seen in the heterogeneity of the sample size, the design of the studies or the different instruments used to measure obesity and depression, all which could significantly influence the results. However, it can be stated that a high percentage of the analysed bibliography, demonstrates that both pathologies are associated, although in some cases it is difficult to determine the significance of this association.
Another strong point in this study is that it highlights the importance of the subtypes of depression, a feature that is not generally taken into account although there is increasing evidence that depressive disorder will bring different entities together, each with their own clinical and therapeutic characteristics. Furthermore, the influence of age, sex or ethnicity over depressive symptomatology validates the change in diagnostic manuals towards a more dimensional perspective, as well as the inclusion of sub-threshold forms of presentation associated with clinical and functional discomfort. These results highlight that the reality of the great psychiatric syndromes is probably much more complex than what it was initially believed to be.
The current systematic review has several limitations. Firstly, the articles were only reviewed by a single researcher and most of these studies were cross-sectional, rendering it impossible to obtain causality relationships from them. Following the type of design, a high percentage of the studies presented a low to moderate methodological quality according to the GRADE scale [
Obesity and depression are disorders with a high prevalence and an extraordinary effect over global morbidity and mortality. The relationship between both disorders has been analysed in scientific literature, obtaining significant associations but also contradictory results. The most current data demonstrates that there is a relationship between both entities, although there is no unanimity when it comes to establishing the meaning of this association. Certain variables such as the subtype of atypical depression, female sex, and African-American ethnicity could influence the relationship between depression and obesity thus it is advised that they be examined in future studies. The limited methodological quality of the articles included in this review, with a large proportion of cross-sectional studies that are very heterogeneous in their design has influence the difficulty to draw clear conclusions. In the future it is recommended to include a larger number follow up of studies that are based on unified criteria.
The authors would like to gratefully acknowledge the collaboration of Department of Psychiatry members in the University of Granada.
The authors have no potential conflicts of interest to disclose.
Conceptualization: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Data curation: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Formal analysis: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Funding acquisition: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Investigation: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Methodology: Luis Gutiérrez-Rojas, Beatriz Villagrasa Blasco. Project administration: all authors. Resources: all authors. Software: all authors. Supervision: all authors. Validation: all authors. Visualization: all authors. Writing—original draft: all authors. Writing—review & editing: all authors.
Flow chart of the literature search.
Depression as a risk factor for obesity.
Obesity as a risk factor for depression.
Clinical trials studying treatment of patients with obesity and depression
Author (year) | Participants | Objectives | Results | Quality of the study |
---|---|---|---|---|
Kiecolt-Glasser et al. [ |
N=58 women (38 breast cancer survivors and 20 controls) | To study the impact of daily stressors and major depression over metabolic responses related to obesity in the presence of high-calorie food | Stress and depression alter the metabolic response to rich in fat foods increasing obesity (up to 104 kcal more per meal) | Moderate |
Lin et al. [ |
N=131 (126 of them included in the analysis) patients admitted into acute hospitalization ward diagnosed with major depression | Changes in the Hamilton and functional scale based on body weight and BMI in those patients treated with 20 mg of fluoxetine for 6 weeks | Patients who did not achieve remission had a higher BMI and greater weight before commencing the treatment | Moderate |
High weight and BMI are correlated with a slower improvement in both symptoms and functionality at the end of treatment | ||||
Toups et al. [ |
N=662 patients with chronic or recurrent major depression, randomized into 3 treatment groups (28 weeks duration, with open phase and single blind phase) BMI was measured before and after the treatment | To assess if BMI has any influence over the response to antidepressant treatment or in its comorbidities | Depression in obesity was common (46.2%) compared to the 25.5% of the sample with normal weight | Moderate |
There were no significant differences in the response to treatment in the different groups | ||||
The comorbidities did vary depending on the weight | ||||
BMI is associated with the clinical presentation and the prevalence of comorbidities, but not to the response in antidepressant treatment |
Longitudinal studies in patients suffering from depression and obesity
Author (year) | Participants | Objectives | Results | Quality of the study |
---|---|---|---|---|
Nigatu et al. [ |
N=1,094, follow up for an average of 2.17 years | To examine the significance of the relationship between major depression and obesity, depending on whether it is a single or recurrent episode of depression | In individuals with obesity there was no increased risk of single major depressive episode (OR=0.75, 95% CI 0.25–2.30), but there was risk of major depression with recurrent episodes (OR=11.63; 95% CI 1.05–128.60) | Low |
Ages between 33 and 79 | There was no association found between a single depressive episode or depression with recurrent episodes and the development of obesity in the future | |||
Laserre et al. [ |
N=3,054 (51.3% women, ages from 35 to 66) | To determine whether the subtypes of major depressive disorder (melancholic, atypical, combined and non-specific) are predictive of adiposity in terms of obesity incidence and changes in BMI | Only patients with atypical depression subtype had an increased risk of obesity with an OR of 3.75 (95% CI 1.24–11.35) | Low |
5.5 follow-up years | The subtype of atypical depression is a strong predictor of obesity | |||
Angstmann et al. [ |
Retrospective N=1,111 with major depressive disorder (including dysthymia). BMI was measured. 75% of the sample were women, average age around 40 (18–92.3) | To assess whether obesity can have a negative effect over the response to multimodal treatment for depression (6 months) | Treatment results after six months were not significantly affected by patients BMI | Low |
Roberts and Duong [ |
N=4,175 adolescents from 11 to 17 years of age. 1 follow-up year. Cohort study. DISC-IV (Diagnostic Interview Schedule for Children) questionnaire. Measure of height and weight. Classification according to BMI | To examine whether obesity increases the risk of developing depression, if depression increases de risk of obesity or if there is a reciprocal effect | Initial weight did not predict major depression or depressive symptoms (non-significant OR and adjusted OR). Major depression increased the risk of future obesity by more than two [OR between obesity in phase 2 and major depression in phase 1 was 2.87 (95% CI 1.34–6.18)] | Low |
Young people who are obese are not more likely to be depressed than non-obese people. However, depressed youth are more likely to become obese | ||||
Godin et al. [ |
N=3,090 people over 65 years of age (without depression). 10 years of cohort follow-up. 1,744 people complete de study. 478 cases of depression. The diagnosis of depression was made with MINI (International Psychiatric Structural Interview) or also if the patient was still taking anti-depressive treatment | To investigate the association of BMI and the risk of developing depression in an older population (this study also took blood pressure into account) | Obese subjects (BMI larger than 30) had an increased risk of developing depression when compared to subjects with a normal BMI (RR=1.60 95% CI 1.03–2.51) | Low |
BMI is prospectively associated with the risk of depression | ||||
Pickering et al. [ |
N=34,653 adults from the USA. Ages 18 and over. | The aim was to determine the incidence in mood disorders, anxiety and substance abuse (DSM IV) and the changes in BMI during the follow-up period | Women who are overweighed, have a higher risk of depression than those with normal weight OR=1.3 CI 95% (1.02–1.56); obese women, also had a higher risk of depression than those with a normal weight OR=1.2 CI 95% (1.02–1.51) | Low |
3 years follow up | ||||
Rating of depression with AUDADIS-IV (Alcohol Use Disorder and Associated Disabilities Interview Schedule) and obesity with BMI |
OR: odds ratio, CI: confidence interval, BMI: body mass index, RR: relative risk
Cross-sectional studies performed in patients with obesity and depression
Author (year) | Participants | Objectives | Results | Quality of the study |
---|---|---|---|---|
Kinley et al. [ |
N=4.181 | To examine the association between cardiac and metabolic conditions including obesity, anxiety and depression | Among depressed individuals (N=699) 130 were obese (16.9%). It calculated the OR of obesity for people with depression adjusted to various confounding factors obtaining an OR of 0.85 (95% CI, 0.66 to 1.09) It concluded that depression was not associated either with cardiac or metabolic conditions, but rather with the deterioration of self-care which had an impact on these health problems | Low |
Ages from 18 to 65 | ||||
Ul-Haq et al. [ |
N=140.564 | To examine the probable relationship between major depression and various measurements of adiposity (BMI, waist circumference, waist-hip index and percentage of body fat) | The OR adjusted for obese participants was of 1.16 (1.12–1.20) using the BMI; 1.15 (1.11–1.19) applying the waist circumference and 1.18 (1.12–1.25) when applying the waist-hip index | Low |
Ages from to 40 to 69 (average age of 57) | There was a significant association between adiposity and gender. Overweight women were at an increased risk of depression with a dose-response effect. However, in men, there was only a significant risk of depression for those with obesity type III | |||
Adiposity has been associated with probable major depression, regardless of the used measurements. The association is stronger in women than in men | ||||
Rottenberg et al. [ |
N=210 people with depression, 195 siblings and 161 healthy controls | To assess whether there is an association between depression and cardiovascular risk factors (including obesity) in adolescents with depression which started during their childhood. To do this, he compares them with adolescent siblings of depressed patients (without depression) and with healthy controls | Major depression in childhood is associated with an unfavourable profile for cardiovascular risk factors. For overweight patients the OR (depressed/controls) was 2.13 (1.0–4.56) and for obese patients the OR (depressed/controls) was 3.67 (1.42–9.52) | Low |
The average age was of 17 in the first group 15.9 in the second one and 15.8 in the third one | ||||
63.3% were men | ||||
Yu et al. [ |
N=4,511 (1,382 men and 3,129 women). Ages varied between 35 and 69 (average age 53). BMI was measured and the questionnaire PHQ-9 was passed, based on DSM-IV criteria. They considered major depression if the score was equal to or greater than 10 | To investigate the association between depressive symptoms and diet quality, physical activity and body composition | Compared with healthy individuals, those with mild and major depression have significantly higher ORs for obesity (BMI) and abdominal obesity. Thus, the OR of obesity (BMI>30) in major depression is 1.56 with a 95% CI of (1.30–1.87) and for abdominal obesity the OR is 1.88 with a 95% CI of (1.58–2.24) | Low |
Vannucchi et al. [ |
Multicenter | To investigate the relationship between obesity and the history of manic or hypomanic symptoms in a sample of patients with major depression | Obese patients belonged more frequently to the bipolar group than non-obese patients. They reported more often an HCL scale of over 14. There were 27 people with bipolar disease in the obese patient group (31.4%) and 92 people in the non-obese group (19.0%). There were significant differences between both groups. In addition, the difference was greater in favour of patients with a BMI of over 35. The more obese a patient was the higher risk he had of suffering from bipolar disorder. Obesity in this sample of patients with a major depressive episode is associated with bipolar disorder | Low |
N=571 | ||||
Ages vary from 18 to 75 | ||||
Roberts and Duong [ |
N=4,175 adolescents with ages between 11 and 17. The population sample is taken from adolescents living in Houston homes, only 66% of them took part in this study. BMI is measured as well as, depression according to Diagnostic Schedule of Interviews for Children and Adolescents (DSM-IV), weight perception and body satisfaction | To examine the association between major depression, obesity and body image among adolescents | Obesity was associated with an increased risk of depression OR=2.51, 95% CI (1.47–4.29) | Low |
However, when the association was examined in models that included weight, major depression and body image and covariates, there was no significant association between major depression and weight, or between body satisfaction and major depression. The real significant association was the relationship with perceived weight and depression | ||||
Thus, even with normal weight, the OR for major depression was greater when the perceived weight was higher | ||||
Chou and Yu [ |
N=10,557 adults over 70 years of age | To reveal the conclusion in the obesity rate associated with classic, atypical and undifferentiated depression compared with those subjects without depression in a representative sample of the population in the USA | It was revealed that after adjusting for sex, age, marital status, race and personal income, the obesity rate was significantly higher for those who had atypical depression than for the rest of the subtypes including controls. The same results were concluded for people that had already passed depression, with current depression and depression throughout their life | Low |
OR (obesity in atypical depression versus obesity control): Lifetime: 4.03; current: 5.53; past: 3.53, all of them significant | ||||
It measured obesity according to BMI (BMI>30), major depression based on AUDASDIS-IV score, and criteria of major depression according to DSM-IV | The rest (classic and indifference vs. control) were not significant | |||
These findings suggest that the heterogeneity of depression should be considered when examining the effect of depression over obesity in the elderly | ||||
Levitan et al. [ |
The group identified 5,092 American adults with past or current depression based on the DSM-IV criteria and 1,500 controls matched by gender. They were divided into three subgroups, depending on the subtype of major depression: classic, atypical and undifferentiated. Those who were both classical and undifferentiated were removed (266) | To examine whether the increased risk of obesity is significant for the basic subtypes of major depression or if it is limited to the atypical subtype | Subjects with atypical depression had noticeably elevated rates of obesity compared to controls and other depressed subjects. OR (atypical vs control): 2.61; 95% CI (2.16–3.16). OR (classic vs. atypical): 0.38; 95% CI (0.32–0.45). OR (atypical versus undifferentiated): 2.27 95% CI (1.90–2.71) | Low |
Only atypical depression is associated with a high risk of obesity | ||||
Merikangas et al. [ |
N=4,150 adolescents with ages between 12 and 19 from the USA. 76% of the initial sample (2001–2004). The study measured weight and height (BMI) subjects were considered obese if IMC was over 95% for their age | To study the association between obesity and depression in this sample of adolescents | After adjusting for sex, race or ethnicity, age and poverty, major depression was not significantly associated with obesity among adolescents in general (depressed obesity/non-depressed obesity) OR=1.6; 95% CI (0.9–2.9). However there was a significant increased risk among men suffering from depression [OR=2.7, 95% CI (1.1–7.1)] and among depressed non-Hispanic blacks [OR=3.1 with a 95% CI (1.1 –8.3)] | Low |
OR: odds ratio, CI: confidence interval, BMI: body mass index, RR: relative risk