A substantial improvement in mental health in adolescents over the first 2 years after gastric bypass was found. Most adolescents had a level of mental health and self‐concept similar to norms, but a marked subgroup showed substantial depressive symptoms 2 years after surgery.

Symptoms of anxiety ( P = 0.001), depression ( P = 0.001), anger ( P = 0.001), and disruptive behavior ( P = 0.022) were significantly reduced at 2 years after surgery, as were obesity‐related problems ( P < 0.001). Self‐esteem ( P < 0.001), self‐concept ( P < 0.001), and overall mood ( P = 0.025) improved significantly. Improvements were mainly observed during the first year after surgery. The second year was characterized by stabilization. Symptoms of anxiety, depression, anger, disruptive behavior, and self‐concept were at normative levels after surgery. However, 19% of the adolescents had depressive symptoms in the clinical range.

Eighty‐eight adolescents (65% girls) aged 13 to 18 years were assessed at baseline and 1 and 2 years after surgery. Generic and obesity‐specific questionnaires were used to evaluate outcomes in mental health, also in relation to age‐ and gender‐specific norms.

Introduction Treatment options for adolescents with severe obesity are urgently needed. While lifestyle interventions initiated in younger ages seem effective, in adolescents they are less successful (1-3). Studies of bariatric surgery for adolescents with severe obesity have shown results in both weight loss and resolution of comorbidities in line with those of adults (4-6). Because it is conducted during a time characterized by intense psychosocial development, the effects of surgery on adolescents' quality of life (QoL) and mental health are of particular interest. Adolescents with severe obesity are a vulnerable group living with a highly stigmatized disease (7, 8), and those presenting for obesity surgery are more heavily burdened with mental health problems than other teenagers (9-11). Symptoms of ongoing depression have been reported in 16% to 39% of adolescents seeking weight loss surgery (9-12). In one study, 68% of adolescents reported a history of depression (11). High levels of anxiety and low self‐esteem have been reported (9) as has poor QoL (10, 12). Previously reported baseline data from the Adolescent Morbid Obesity Surgery (AMOS) study showed that 41% of patients had been under treatment in a pediatric psychiatric unit [versus a prevalence of 15% in a general Swedish sample of children and adolescents under the age of 18 years (13)], and 31% had a neuropsychiatric diagnosis (4). Large‐scale, long‐term follow‐ups of adults after bariatric surgery show that QoL and different aspects of mental health improve significantly post‐surgery (14-17) and that these improvements are sustained up to 6 years after surgery (18). However, most prospective studies have included patients with a mean age >40 years, and there is a lack of studies investigating mental health outcomes among adolescents who have undergone surgery. Short‐term outcome studies in adolescents have shown substantial improvements in psychological well‐being during the first year after surgery (9, 19, 20). One study found a tendency to improvement in mental health already when adolescents were waiting for surgery (21). Outcome studies suggest not only psychological improvement but also normalization of psychological health after surgery (9, 20). A small study of 16 adolescents demonstrated that improvements in psychosocial well‐being are sustained up to 2 years (22). Improvements in adolescents appear to mimic changes in adults undergoing surgery, with major improvements occurring during the first year of rapid weight loss. However, not all adolescents have a positive outcome. In AMOS we previously reported two cases of attempted suicide and five cases of drug abuse during the first two postoperative years (4), as well as impaired psychological health in 16% of patients 4 months after surgery (9). The aim of the present study was to explore 2‐year outcomes in generic and obesity‐specific psychological health in Swedish adolescents (13‐18 years) undergoing laparoscopic gastric bypass. We hypothesized that trends in psychological well‐being observed among adults should also be found in adolescents, i.e. major improvements during the first postoperative year and a deceleration of improvement or minor decline during the second year.

Methods AMOS is an ongoing Swedish 10‐year prospective study examining the safety and efficacy of gastric bypass in adolescents with severe obesity. Inclusion and exclusion criteria are presented in detail elsewhere (4). Eligibility criteria were age 13‐18 years and body mass index (BMI) ≥ 40 or ≥ 35 with comorbidity. The adolescent should have attended an obesity treatment program at a pediatric clinic for at least 1 year before entering the study. Exclusion criteria included psychotic disease and ongoing drug abuse. This study sample from the AMOS cohort consists of 88 consecutively enrolled adolescents (65% girls and 35% boys) undergoing laparoscopic gastric bypass between May 2006 and January 2010. Mean age at surgery was 16.8 years (SD ± 1.2; range 13‐18). Participants were enrolled and followed‐up at the three largest childhood obesity units in Sweden: Stockholm, Gothenburg, and Malmo. All surgeries were performed at Sahlgrenska University Hospital, Gothenburg. The study was approved by the regional ethics committee. Procedure Data were collected at inclusion and at the 1‐ and 2‐year post‐surgery follow‐ups. All adolescents visited the nearest study centre for assessment. A battery of generic and obesity‐specific self‐assessment questionnaires was used to measure psychological health. Questionnaires were collected by study coordinators; however, two questionnaires, the Beck Youth Inventories (BYI) and Beck Depression Inventory II (BDI‐II), were administrated by a clinical psychologist and were only collected when a psychologist was available at the clinic. Therefore, the BYI and BDI‐II (BDI‐II only administered at follow‐ups) were collected from 72% at baseline, in 59% at the 1‐year follow‐up, and in 72% at the 2‐year follow‐up. For other questionnaires the collection rates varied between 85 and 95%. Available data is shown in Table 1. Table 1. Anthropometrics and psychological health in adolescents with severe obesity at baseline and 1 and 2 years after gastric bypass Baseline n 1 year post‐surgery n P value, 1 year vs. baseline 2 years post‐surgery n P value, 2 years vs. baseline P value, 2 years vs. 1 year BMI 45.6 (44.4‐46.8) 86 30.9 (29.9‐31.9) 85 <0.001 30.1 (29.0‐31.2) 85 <0.001 0.065 Anxiety BYIa 14.2 (12.1‐16.4) 63 10.2 (8.2‐12.3) 52 <0.001 10.5 (8.5‐12.7) 63 0.001 0.763 Depression BYIa 14.1 (12.0‐16.6) 63 9.5 (7.5‐11.8) 52 <0.001 9.9 (7.8‐12.4) 63 0.001 0.694 Anger BYIa 11.3 (9.4‐13.5) 63 9.3 (7.3‐11.6) 52 0.056 7.8 (5.8‐10.1) 62 0.001 0.125 Disruptive behavior BYIa 4.8 (3.7‐6.0) 63 3.7 (2.8‐4.8) 52 0.048 3.4 (2.5‐4.5) 63 0.022 0.585 Self‐concept BYI 34.6 (32.2‐37.1) 63 41.3 (38.6‐44.1) 52 <0.001 40.5 (37.8‐43.3) 63 <0.001 0.587 Rosenberg Self‐Esteema 20.6 (19.0‐22.0) 82 24.2 (23.0‐25.2) 84 <0.001 23.9 (22.5‐25.2) 75 <0.001 0.648 Pleasantness MACL 2.88 (2.76‐2.99) 82 3.08 (2.97‐3.20) 83 <0.001 3.04 (2.92‐3.17) 74 0.015 0.509 Activation MACL 2.61 (2.50‐2.72) 81 2.83 (2.71‐2.95) 83 <0.001 2.71 (2.58‐2.84) 75 0.124 0.058 Calmness MACL 2.61 (2.49‐2.72) 82 2.85 (2.74‐2.97) 83 <0.001 2.76 (2.63‐2.89) 75 0.027 0.129 Overall mood MACL 2.70 (2.60‐2.79) 82 2.92 (2.82‐3.03) 83 <0.001 2.83 (2.71‐2.95) 75 0.025 0.084 OP 51.5 (46.0‐57.0) 82 29.4 (24.4‐34.4) 81 <0.001 32.9 (27.2‐38.5) 75 <0.001 0.187 Measures Anthropometrics Weight was measured on an electronic scale to the nearest 0.1 kg with the subject wearing light clothing. Height was measured without shoes to the nearest 0.1 cm using a wall‐mounted standardized stadiometer. BMI was calculated as kg/m2. Beck Youth Inventories BYI consists of five self‐report inventories for children and adolescents aged 7 to 18 years and assess symptoms of anxiety, depression, anger, disruptive behavior, and self‐concept (23). Scale scores range from 0 to 60, and higher scores on the anxiety, depression, anger, and disruptive behavior inventories indicate more symptoms, while a higher score on the self‐concept inventory reflects a more positive self‐concept. Swedish gender‐specific norms are available for children aged 9 to 18 and scores are transformed to percentiles. Percentiles indicate whether a respondent's symptoms are greater or equal to those of sex‐ and age‐matched peers. Symptom severity is classified according to standardized cut‐offs. On four of the scales (anxiety, depression, anger, and disruptive behavior) the following cut‐offs are used for categorization: ≥90th percentile highly elevated, 89th‐76th percentiles slightly elevated, ≤75th percentile in the average range. In the self‐concept inventory the following cut‐offs are used for categorization: ≤10th percentile very low self‐concept, 11th‐25th percentiles somewhat low self‐concept, 26th‐89th percentiles average, and ≥90th percentile high self‐concept (23). Beck Depression Inventory II The BDI‐II assesses depressive symptoms in adolescents (≥13 years) and adults (24), and is a valid tool for screening for clinical mood disorders in bariatric samples (25). BDI‐II is widely used to assess depressive symptoms in adolescents (10, 12, 19, 20, 22) and adults (26, 27) undergoing obesity surgery. In a clinical setting, scores ≤13 are categorized as minimal symptoms, 14‐19 mild symptoms, 20‐28 moderate symptoms, and 29‐63 severe symptoms. A score ≥17 is used as a conservative cut‐off for depressive symptoms at the clinical level (24). Rosenberg Self‐Esteem The Rosenberg Self‐Esteem (RSE) questionnaire is widely used to assess global self‐worth in adolescents and adults (28). The RSE consists of 10 items and total score range between 0 and 30. Higher scores reflect higher self‐esteem. Mood Adjective Check List The Mood Adjective Check List (MACL) assesses both positive and negative moods and contains 38 adjectives. The MACL covers three major dimensions of mood: pleasantness/unpleasantness (e.g., optimistic/resigned), activation/deactivation (e.g., active/passive, apathetic), and calmness/tension (e.g., relaxed/tensed). An overall mood score is also calculated. Scale scores range from 1 to 4, with higher scores indicating a more positive mood. The MACL is a valid instrument for detecting changes in mood in populations with obesity during weight loss and relapse (14, 29, 30). Age‐ and gender‐specific norms are available. Obesity‐related Problems scale The Obesity‐related Problems scale (OP) is a condition‐specific questionnaire assessing the impact of obesity on psychosocial functioning in everyday life. Subjects estimate how disturbed they are because of their weight or body shape in social situations such as attending parties, bathing in public places, and intimate situations. The OP consists of 14 items measured on a four‐point scale. It is a reliable and valid questionnaire for assessing weight‐related psychosocial impairment in populations with obesity and is responsive to change in weight status (31). Responses are aggregated on a scale of 0‐100. A score <40 is categorized as mild impairment, 40‐59 as moderate impairment, and ≥60 as severe impairment. Internal consistency of mental health variables Internal consistency was calculated for all administered mental health variables at all assessment points. Cronbach's alpha varied between 0.86 and 0.96, indicating good to excellent internal consistency. Statistical analysis Descriptive statistics are given as mean, confidence interval (CI), standard deviation (SD), and range where appropriate. A sensitivity analysis comparing persons with complete and missing data was conducted with t tests for continuous and chi‐square tests for dichotomous variables. Multilevel mixed‐effect regression models were used to analyze the data to assess changes over the study period. Because observations were considered nested within persons, standard errors (SE) were calculated by taking into account the repeated measurements. Mean changes over time are expressed with 95% CI. Variables which were not normally distributed (BYI anxiety, depression, anger, and disruptive behavior, BDI‐II, and RSE) were transformed with zero‐skewness log‐transformation. Change over time and correlations were analyzed with the transformed variables. Before reporting the means and CI, the results were retransformed back to the original scale. Observed values were used to calculate the standardized response mean (SRM). The SRM estimates the magnitude of change within a group between two assessment points and is calculated as mean change divided by the SD of change. SRM is evaluated according to standard criteria for effect sizes (ES) in which ES < 0.2 is considered trivial, 0.2 to <0.5 is small, 0.5 to <0.8 is moderate, and ≥0.8 is large (32). Pearson's r was used to test for correlations. All P values are two‐tailed and P < 0.05 was considered statistically significant. Statistical analyses were carried out using the Stata statistical package 12.1 (Stata‐Corp, 2011, Stata Statistical Software: Release 12.1, College Station, TX; StataCorp LP) and SPSS 20.0 (IBM, Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM).

Results Missing data An analysis was conducted for all variables at baseline comparing adolescents with complete data in relation to those having missing data. There were no statistically significant differences on any variable (all P > 0.05). Furthermore, there were no significant differences for age (P = 0.705) or gender (P = 0.203). BMI Mean BMI decreased significantly from baseline until 2 years after surgery (Table 1 and Figure 1a). At the 2‐year follow‐up, 50% of the adolescents were no longer in the obese range (BMI < 30). The other 50% were still classified as obese, and 4 of these (5%) remained class III obese (BMI ≥ 40). None had a BMI < 20. Figure 1 Open in figure viewer PowerPoint BMI and mental health data in adolescents before and after gastric bypass. Black line = mean (95% CI). Grey lines = individual development for adolescents with more than one assessment. Abbreviations: BMI = body mass index, BYI = Beck Youth Inventories, RSE = Rosenberg Self‐Esteem, OP = Obesity‐related Problems scale. Because of non‐normal distribution, BYI variables and RSE were transformed with zero‐skewness log‐transformation before analyses. In reporting the means and confidence intervals (CI), these are retransformed back to the original scale. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Anxiety, depression, anger, and disruptive behavior Symptoms of anxiety, depression, anger and disruptive behavior measured on the BYI were significantly decreased 2 years after surgery compared to baseline (Table 1). The effect size of the 2‐year change was moderate for anxiety (ES = 0.53) and small for depression (ES = 0.47), anger (ES = 0.41), and disruptive behavior, (ES = 0.25). Reductions in anxiety, depressive symptoms and disruptive behavior were observed during the first year after surgery while the second year was characterized by stabilization (Table 1 and Figure 1b‐c). Anger symptoms gradually decreased as no change reached significance between consecutive assessments, but there was a significant change from baseline to 2 years (Table 1). Descriptive values for percentiles for baseline and 2‐year follow‐up are presented in Table 2. The mean BYI percentiles at baseline indicate that adolescents with severe obesity have more symptoms of anxiety, depression, anger, and disruptive behavior before bariatric surgery than other adolescents. The mean percentiles 2 years after surgery indicate a general alleviation of symptoms, but some continued to have highly elevated symptoms at the 2‐year post‐surgery follow‐up. Table 2. Descriptive percentile values at baseline and 2 years after surgery for BYI variables Mean percentilea (±SD) Median percentilea (IQR) Percentile rangea (min‐max) Average symptomsb Slightly elevated symptomsb Highly elevated symptomsb n BYI anxiety, baseline 67.0 (±28.3) 79.4 (41.5) 3.8‐99.9 44% 37% 19% 63 BYI anxiety, 2‐year follow‐up 50.9 (±30.6) 45.3 (46.4) 1.6‐99.9 76% 8% 16% 63 BYI depression, baseline 66.0 (±26.9) 71.5 (36.6) 9.1‐99.9 56% 21% 24% 63 BYI depression, 2‐year follow‐up 50.9 (±31.3) 52.0 (53.3) 1.9‐99.7 71% 13% 16% 63 BYI anger, baseline 61.7 (±27.0) 65.8 (46.4) 7.9‐99.7 59% 22% 19% 63 BYI anger, 2‐year follow‐up 46.9 (±33.9) 40.8 (64.1) 4.2‐99.0 69% 13% 18% 62 BYI disruptive behavior, baseline 62.0 (±23.3) 60.4 (41.4) 13.1‐98.7 62% 29% 9% 63 BYI disruptive behavior, 2‐year follow‐up 53.3 (±25.9) 52.8 (40.2) 13.1‐99.6 78% 6% 16% 63 Two years after surgery the mean BDI‐II depression score was in the minimal range (m = 10.4, SD ± 13.6, range 0‐52, n = 63). According to cut‐offs, 76% had depressive symptoms in the minimal range, 5% in the mild range, 6% in the moderate range, and 13% in the severe range. A score ≥17 indicates clinical depression, and 19% scored above this cut‐off 2 years after surgery. Self‐concept and self‐esteem Self‐concept (BYI) and self‐esteem (RSE) were significantly improved 2 years after gastric bypass (Table 1), with a moderate ES (0.65) for self‐concept and small (0.40) for self‐esteem. The improvement occurred during the first year, and changes between 1 and 2 years after surgery were not significant (Table 1 and Figure 1d‐e). At baseline the mean percentile for self‐concept was 36.8 (SD ± 26.3, range 1.8‐97.3) and 17% were categorized as having a very low self‐concept, 25% a somewhat low self‐concept, 56% an average self‐concept, and 2% a high self‐concept. Two years after surgery the mean percentile was 54.4 (SD ± 28.7, range 0.4‐97.3); 10% reported a very low self‐concept, 8% a somewhat low self‐concept, 68% an average self‐concept, and 14% a high self‐concept. Mood Overall mood and two specific aspects of mood, pleasantness and calmness, were significantly improved 2 years after surgery (Table 1). The effect size of change for overall mood was small (ES = 0.28). The improvement took place during the first year, while a non‐significant decline was observed during the second year (Table 1). Activation was significantly improved during the first year after surgery, but at the 2‐year follow‐up the improvement no longer reached significance (Table 1). At follow‐up 2 years after surgery lower mean scores were observed for all aspects of mood compared to age‐matched norms. For overall mood the mean score 2 years after surgery was 0.8 SD below norms. Obesity‐related problems Obesity‐related problems were significantly reduced at year 2 after surgery (Table 1) and the change corresponded to a moderate ES (0.65). The improvements were noted during the first year, with a non‐significant decline during the second year (Table 1 and Figure 1f). Before surgery, the adolescents mean score indicated moderate impairment and at year 2 the mean score indicated mild impairment. There was no significant correlation between the OP score and BMI at any time point nor was there any significant correlation between percent weight loss (%WL) from baseline to 2‐year follow‐up and improvement in OP during the same period (r = 0.10, N = 73, P = 0.40), still OP showed excellent internal consistency at each time point. However, improvement in OP correlated negatively and significantly to BYI depression (r = −0.28, n = 54, P = 0.043), and BDI‐II (r = −0.28, n = 54, P = 0.038) and correlated positively to MACL overall mood (r = 0.32, n = 72, P = 0.006) and RSE (r = 0.28, n = 72, P = 0.016) at year 2. Correlation between weight loss and improvement in mental health There was no significant correlation between %WL and change in any mental health variable (r = −0.19 to 0.037, n = 53‐73, P = 0.178‐0.794) 2 years after surgery.

Discussion This is the first study with a larger sample showing that different aspects of mental health, mood, self‐esteem and obesity‐related problems are significantly improved in adolescents 2 years after undergoing bariatric surgery. As shown in other studies of adolescents (19, 20) and adults (14, 15), major improvements take place during the first year after surgery when weight loss is rapid. In this study, the second year was characterized by stabilization. No changes between the first and second years' follow‐up were significant, although results from other studies have suggested a relative decline in mental well‐being during the second postoperative year in both adolescents and adults (15, 22). Reduction in depressive symptoms is generally seen after bariatric surgery in both adults (17) and adolescents (33), but results for changes in anxiety in adults are inconsistent (34, 35). It has been suggested that anxiety is less weight dependent than depression in populations with obesity (14). In this study, we found that anxiety symptoms were significantly reduced in adolescents after 2 years, which to our knowledge has not been previously reported. While fewer than half of the patients had average anxiety symptoms at baseline, 2 years after gastric bypass three out of four had average anxiety symptoms. Overall, our data show that adolescents undergoing gastric bypass achieve a level of mental health and self‐concept comparable to norms at 2 years after surgery. These findings emphasize the importance of using domain‐ and age‐specific instruments to capture clinically meaningful changes in mental health in adolescents. Previously reported 2‐year QoL results from AMOS suggested no significant improvements in role‐emotional, mental health, or the mental health summary component as measured by the generic Short Form‐36 Health Survey (4). In the present study, only one mental health variable (activation) did not improve from baseline to the 2‐year follow‐up. As assessed on the OP, adolescents are significantly less disturbed by their weight and body shape in social situations at 2 years after gastric bypass, despite many adolescents expressing severe self‐consciousness arising from excess skin (36). The OP is designed to measure the impact of overweight and body shape on psychosocial health and is highly sensitive to change in weight (31), i.e. the greater the weight loss, the greater the improvement in weight‐related psychosocial functioning. In the present study, we found no significant correlation between %WL or BMI and improvements in OP, maybe explained by a substantial weight loss in most adolescents. Instead there were significant correlations between depressive symptoms, mood, and self‐esteem at year 2 and improvements on the OP. Increasing mental well‐being and global self‐worth may be crucial for reducing social impairment due to concerns about weight and body shape in adolescents. Several findings in the present study add evidence that adolescents seeking bariatric surgery are a vulnerable group. They appear as psychosocially even more burdened than adults undergoing obesity surgery. In this study, the highest mean value for overall mood (2.92) was reported at 1‐year follow‐up, which is similar to the baseline value (2.93) of 665 adult surgical cases (mean: 47.0 years) in the SOS‐study (14). Thus, mood at its highest point after surgery in adolescents is similar to the average level in adults presenting for weight loss surgery. Norm data from general population do not suggest that this difference could be expected just based on age. Similarly, in a substantial number of cases (13%), we found severe depressive symptoms at 2 years after surgery as assessed with BDI‐II. In a recent study by Mitchell et al. only 0.2% of adults had BDI scores in the severe range 2 years after surgery (mean age at baseline: 46) (15). Our results are in line with a 2‐year follow‐up of 16 adolescents in which 14.3% had a BDI‐II score ≥17 (22) compared to 19% in the present study. The high prevalence of severe depressive symptoms in this cohort must not be overlooked given the link between depressive disorders and suicide (37), the increased risk of suicide after bariatric surgery (38) and the two cases of attempted suicide in AMOS (4). The findings suggest that the needs for psychological and psychiatric treatment for depression are going unmet in adolescents undergoing bariatric surgery. Studies of adolescents demonstrating severe depressive symptoms after bariatric surgery are needed to detect this high‐risk group even before surgery and to develop targeted interventions. The main limitation of this study is the lack of a control group. Little is known about the natural development of mental health in adolescents with severe obesity over time independent of weight loss. However, several of the instruments used allowed comparisons to age‐matched population norms. The study relies on self‐report questionnaires. More informants or diverse methods (e.g., clinical interview) would have yielded a more comprehensive picture of the psychosocial status of the adolescents. Also, BYI norms for the age span 9‐18 were used to evaluate mental health, even though most subjects were over 18 years at the 2‐year follow‐up. Time trends according to the BYI‐manual show an increase in symptoms and a reduced self‐concept in the higher age range (23). Using aggregated norms for 9‐ to 18‐year‐olds may lead to under‐estimation of mental health in those over 18. Strengths of the present study are the prospective longitudinal design, a high retention of participants in the study, and the use of both generic and obesity‐specific questionnaires.

Conclusion In summary, we found broad improvements in mental health, self‐esteem, mood, and obesity‐related problems in adolescents 2 years after treatment for severe obesity by gastric bypass. Symptoms of depression, anxiety, anger, disruptive behavior, and self‐concept were at the same level as norms for adolescents, indicating a mental health in the normative range, 2 years after surgery. The improvements took place mainly during the first year after surgery, and the second year was characterized by stabilization. However, mood was still remarkably lower than that of age‐matched norms, and 19% showed depressive symptoms at a clinical level 2 years after surgery. We strongly advocate repeated monitoring of adolescents after bariatric surgery to ensure that adolescents with mental health problems have access to the supports they need.

Acknowledgments The authors express their appreciation to Torsten Ohlsson, Gunilla Lundstedt, Gudrun Furumark, Rebecca Rickert‐Olsson, Jessica Sjövall, Anna Bengtsson‐Strandqvist, Jennifer Curland, John Chaplin, and Jane Klintbäck‐Gabrielsson for their valuable help with the data collection. We also would like to thank the teams at the childhood obesity units in Stockholm, Gothenburg, and Malmö.