Cognitive Performance as Predictor and Outcome of Adolescent Bariatric Surgery

A Nonrandomized Pilot Study

Eleanor R. Mackey, PhD; Marni Jacobs, PhD; Evan P. Nadler, MD; Alexandra Olson, MA; Alaina Pearce, MA; J. Bradley C. Cherry, JD; Sheela N. Magge, MD, MCSE; Michele Mietus-Snyer, MD; Chandan Vaidya, PhD


J Pediatr Psychol. 2018;43(8):916-927. 

In This Article

Abstract and Introduction


Objectives: Evidence in adults suggests that improvements in cognitive performance may follow weight loss resulting from bariatric surgery, and baseline cognitive performance may be associated with weight loss following surgery. This has not been evaluated in adolescents.

Method: Participants were 38 adolescents of age 14–21 years composed of three groups: (1) 12 adolescents with severe obesity who received vertical sleeve gastrectomy during the study (VSG); (2) 14 adolescents with severe obesity who were wait-listed for VSG (WL); and (3) 12 healthy weight controls (HC). Participants completed testing of visual memory, verbal memory, and executive functioning at baseline (T1), which occurred presurgery for the VSG group, and approximately 4 months after baseline (T2). Body mass index (BMI) was assessed at T1, T2, and additionally at 6 months following VSG for the adolescents who received surgery.

Results: Although there was evidence of greater improvement for the VSG as compared with WL and HC groups in visual and verbal memory, group differences did not reach significance and effect sizes were small (η2 < 0.01). There was a significant positive association between indices of baseline executive functioning and excess BMI loss at 6 months postsurgery.

Conclusions: This small pilot study showed no significant differences by group in cognitive performance post-VSG. There was a significant association of baseline cognitive performance with weight loss outcomes. Given the very preliminary nature of these results in a small sample, future research should examine these relationships in a larger sample and evaluate mechanisms of these associations (e.g., insulin resistance, sleep, physical activity).


Severe obesity is estimated to affect 9.1% of adolescents in the United States (Ogden et al., 2016), with rates increasing more rapidly than any other category of obesity (Skinner & Skelton, 2014). Consequences of severe obesity include both poor psychosocial and physical outcomes as well as the risk of premature death (Kelly et al., 2013; Ogden, Carroll, Kit, Flegal, 2014). Additionally, severe obesity is associated with cognitive deficits and poorer school performance (Freidl et al., 2013). Bariatric surgery is the treatment option with the most significant and sustained weight loss in youth with severe obesity (Inge et al., 2016; Paulus et al., 2015) and has been demonstrated to significantly reduce weight and improve or eliminate comorbidities including hypertension, dyslipidemia, and type 2 diabetes (Inge et al., 2016). However, weight loss following surgery is highly variable and predictors of outcomes poorly understood (Inge et al., 2016; Nadler, Barefoot, & Qureshi, 2012).

Previous data have established a robust connection between executive functioning and weight status, as well as with behaviors that may contribute to onset or maintenance of obesity (Hayes, Eichen, Barch, & Wilfley, 2018). For example, poor executive functioning may in part contribute to disordered eating behaviors, such as binge eating (Kittel, Schmidt, & Hilbert, 2017). Existing research has identified a transactional association between executive functioning and obesity, such that poorer executive functioning is prospectively associated with weight gain and obesity (Goldschmidt, Hipwell, Stepp, McTigue, & Keenan, 2015) and obesity associated with poorer executive function. For example, a systematic review of 31 studies demonstrated that children and adolescents with obesity perform worse on a variety of tasks of executive function than their healthy weight peers (Reinert, Po'e, & Barkin, 2013). Given the close two-way association between obesity and executive function, Hayes et al. (2018) note the importance of evaluating the effect of intervening on executive function in conjunction with treatment for obesity, as well as the impact of obesity treatment on improvements to executive functioning. Moreover, they note that the directionality of this association should be studied in greater depth. The current study, therefore, aims to fill this gap in the literature through the study of a population of adolescents with severe obesity experiencing rapid weight loss following bariatric surgery.

The role of impulsivity is particularly relevant for adolescents, as executive functioning is still developing during this period. In adolescents with obesity, developmentally normal weaker executive functioning may be compounded by additional deficits as compared with peers in normal weight categories (Braet, Claus, Verbeken, & Van Vlierberghe, 2007; Davis & Fox, 2008; Nederkoorn, Braet, Van Eijs, Tanghe, & Jansen, 2006; Pearce, Mackey, Kietlinski, Nadler, & Vaidya, 2014; Yau, Castro, Tagani, Tsui, & Convit, 2012). These deficits in executive function appear to be associated with maladaptive behaviors (Gettens & Gorin, 2017), such as dysregulated eating behaviors (Galanti, Gluck, & Geliebter, 2007; Gowey et al., 2017; Liang, Matheson, Kaye, & Boutelle, 2014; Nasser, Gluck, & Geliebter, 2004) and less physical activity (Joseph, Alonso-Alonso, Bond, Pascual-Leone, & Blackburn, 2011; Loprinzi, Herod, Cardinal, & Noakes, 2013; Riggs, Chou, Spruijt-Metz, & Pentz, 2010). The evidence of deficits in cognitive performance is supported by imaging studies showing weaker activation in the dorsolateral prefrontal cortex (Carnell et al., 2017; Reinert et al., 2013) and anterior cingulate cortex (Yau, Kang, Javier, & Convit, 2014) of adolescents with obesity, areas of the brain that regulate attention and inhibition.

Memory has also been implicated in obesity. As with executive functioning, this may be a transactional relationship, as poorer memory may be associated with increased caloric intake (Robinson et al., 2013), and insulin resistance, which results from obesity, may be a key mechanism by which memory is affected by obesity (Convit, 2005) because of the impact of insulin on hippocampal processes (McNay et al., 2010). Indeed, memory performance has been found to be poorer in adolescents with obesity than their healthy weight peers, though a systematic review found inconsistency in findings across studies (Liang et al., 2014). Studies of adolescents with severe obesity but without associated comorbidities found no differences in memory functioning compared with healthy peers (Yau et al., 2014), reflecting the importance of examining memory functioning in adolescents with severe obesity who may be more likely to have insulin resistance (Yau et al., 2014) while accounting for the lack of memory differences in adolescents with uncomplicated obesity. Research on adult bariatric surgery patients demonstrates improved memory function as early as 12 weeks and as long as 12 months following surgery relative to control participants with obesity (Alosco, Spitznagel, et al., 2014; Gunstad et al., 2011; Miller et al., 2013). Therefore, it is important to assess differences in memory, both visual and verbal, in adolescents with severe obesity, as well as any potential improvements associated with significant weight loss, which may be accompanied by decreased insulin resistance (Inge et al., 2016).

Evidence in adults indicates that improvements in cognitive performance may result from the significant weight loss following surgery (Alosco, Galioto, et al., 2014; Thiara et al., 2017; Veronese et al., 2017) and that baseline cognitive performance may likewise impact weight loss outcomes (Spitznagel et al., 2014; Spitznagel, Alosco, et al., 2013). However, these associations have not yet been studied in adolescents. Although the adult literature can inform understanding of adolescent cognitive functioning with regard to obesity and bariatric surgery, adolescence is a unique period in cognitive development that requires particular attention. Specifically, adolescent brains are developing rapidly, particularly with regard to executive function and reward sensitivity (Steinberg, 2005). Therefore, changes following surgery may be different from adults in terms of both type and trajectory of change. Existing evidence also suggests unique developmental outcomes of adolescents compared with adults in bariatric surgery, with adolescents receiving bariatric surgery exhibiting more metabolic improvement relative to adults, but fewer hormonal changes (Lawson et al., 2006; Sysko et al., 2012), suggesting processes specific to this developmental group following surgery and the value of studying adolescents independently.

The current study was a small pilot study designed to evaluate preliminary evidence of cognitive changes in adolescents undergoing vertical sleeve gastrectomy (VSG) as compared with adolescents who were eligible for VSG but were not having surgery within the study period, and adolescents of healthy weight matched for age and socioeconomic status (SES) to further control for practice effects and potential baseline differences in cognitive functioning. The current study aimed to: (1) evaluate whether, as hypothesized, there was a greater improvement in cognitive function in the VSG group (VSG) as compared with the wait list (WL) and healthy control (HC) groups between baseline (T1) and 3–4 month follow-up (T2); and (2) evaluate whether, as hypothesized, baseline cognitive function (T1) was associated with weight loss at 3- and 6-month post-VSG (T2 and T3, respectively).