Study finds correlation between depressive symptoms and the effectiveness of BMS

Despite the improvements in physical and mental health after bariatric and metabolic (BMS) procedures there is a possibility of a correlation between depressive symptoms and the effectiveness of bariatric surgery, according to a short-term study by researchers at I-Shou University, Kaohsiung City, Taiwan. The study authors said the findings underscore the importance of continuous mental health support and comprehensive care for BMS patients, both before and after the procedure, to ensure sustained improvements in both physical and mental health.

The aim of this Taiwanese study was to evaluate the changes in physical and mental health before and after BMS, and investigate the association between surgical outcome and mental health status, particularly in the population of ethnic Chinese patients.

The study population included patients who had undergone BMS at least one year prior (with the follow-up durations predominantly within two years). The researchers collected and compared pre- and post-operative mental health status (using the Chinese Health Questionnaire, CHQ, and the Taiwanese Depressive Questionnaire, TDQ) and physical indicators to:

• determine whether patients’ mental health improves after bariatric surgery

• explore the relationship between the degree of mental health improvement and the effectiveness of weight loss; and

• investigate whether mental health factors can predict the effectiveness of weight loss. It is expected that understanding the impact of mental health factors on bariatric surgery will enhance treatment outcomes for obese patients.

  
  

In addition, formal psychiatric diagnoses were confirmed by psychiatrists to analyse the differences between the groups with and without such diagnoses.

In total, 147 patients were included in the study (~70% female), most of the patients were unmarried (66.7%) and had tertiary education (53.7%) with the mean age of the patients was 33.84 years. Most patients had full-time or part-time jobs (77.6%). The mean follow-up duration was 16.7 months (SD 8.2), with a range between 10 and 45 months.

Compared with the pre-operative period, post-operative results showed a significant reduction in body weight and BMI. The average reduction in body weight was 39.43kg and the average reduction in BMI was 13.46kg/m². All other physical health indicators also showed significant improvements: systolic blood pressure (SBP) decreased by 21.76 mmHg (SD 20.97), diastolic blood pressure (DBP) decreased by 15.15 mmHg (SD 15.70), and total cholesterol decreased by 28.72 mg/dL (SD 34.75).

Key outcomes on mental health

The authors reported that post-surgery results indicated an improvement in mental health. There was a significant decrease in both CHQ and TDQ scores. The CHQ score decreased by 1.52 points (SD 2.76) and the TDQ decreased by 5.08 points (SD 8.58). In addition, there was a statistically significant correlation between the body weight change and the CHQ change (r=0.171, p=0.038). The BMI change and the TDQ change showed a positive correlation (r=0.167, p=0.043). Additionally, there was a negative correlation between the post-operative BMI and the TDQ change (r=-0.194, p=0.018).

The prevalence of any psychiatric disorder in these patients was found to be 34%. Patients with pre-surgical mental illness had significantly higher pre-operative CHQ and TDQ scores compared to those without mental illness. However, they found no significant difference in pre-operative BMI between the two groups. Post-operative results showed that the group with mental illness had a higher BMI (mean 29.25, SD 7.42) vs. the group without mental illness, although this difference was not statistically significant. The effectiveness of weight loss (%TWL) was 31.67% (SD 13.16) in the group with mental illness and 34.03% (SD 12.13) in the group without mental illness, but again, this difference was not statistically significant. However, the post-operative CHQ and TDQ scores remained significantly higher in the group with mental illness compared to those without.

In the multiple linear regression models, in model 1 while %TWL was used as dependent variable, they included TDQ score, age, sex, education level, employment status, marital status, follow-up duration and history of psychiatric treatment as independent variables. Married status and tertiary education level (≥13 years) were statistically significant (standardized coefficient β=-0.353, p=0.001; β=-0.195, p=0.030, respectively; R² =0.111) but not the TDQ score.

In model 2, the term TDQ x follow-up duration was introduced in addition to the aforementioned preserved independent variables. The TDQ-by-duration interaction term was significantly associated with %TWL (β = 0.559, p=0.022), indicating that TDQ-by-duration was detected.

Furthermore, married status (β=-0.322, p=0.001) and tertiary education level (β=-0.174, p=0.049) remained significantly and negatively associated.  However, pre-operative CHQ score did not predict %TWL, after controlling for all potential variables (including CHQ-by-duration interaction). Conversely, when CHQ or TDQ change was employed as the dependent variable and %TWL as the independent variable, no significant association was observed between %TWL and CHQ or TDQ change, after controlling for other factors.

Overall, the authors found that patient’s mental health improved after bariatric surgery, even for those with psychiatric disorders. Weight loss has been shown to improve the mental health of individuals with psychiatric disorders, although this improvement is not necessarily complete. According to the authors this indicates that mental health is a complex phenomenon, influenced by multiple factors beyond weight and obesity.

“This study explored the changes in mental health status preceding and following bariatric surgery (based on follow-up durations of less than two years, largely) and their association with weight changes in Chinese patients with clinically severe obesity,” the authors concluded. “About 34% of bariatric surgery patients had a history of psychiatric disorders before surgery, and the presence of pre-operative psychiatric disorders did not significantly affect weight change after surgery.”

The findings were featured in the paper, 'A longitudinal study of the association between the outcome of bariatric surgery and mental health indicators in Chinese patients: an examination of the interaction effect', published in BMC Psychiatry. To access this paper, please click here