Impact of social connectedness on weight loss outcomes in an online program

Obesity is linked to many negative health consequences. While online behavioral weight loss programs (BWL) are an effective treatment for obesity, weight losses are modest. Social connectedness has been found to improve weight loss outcomes and previous findings suggests that it may be especially important for people of color. The present study investigated the impact of social connectedness (structural connectedness, or network size; relationship quality, and functional connectedness, or social support) on weight loss outcomes in an online BWL program and whether Black race or Hispanic ethnicity moderates the relationship between social connectedness and weight loss. Participants (N = 387) enrolled in a 16-week online BWL program and completed measures of social connectedness before treatment and had their weight measured. Individuals with less structural connectedness (smaller social networks) had greater weight losses. Further, higher levels of functional connectedness (affectionate support, positive support, and relationship quality) mediated the relationship between smaller network size and better weight loss outcomes. Black race / Hispanic ethnicity did not moderate the relationship between social connectedness and weight loss. These findings suggest that the quality of one's relationships, not the size of one's social network, is important for weight loss. Future studies may examine whether online BWL programs that build relationship quality and affectionate and positive support in participants' existing social networks improve overall weight loss outcomes.

Abdominal Obesity Genetic Variants Predict Waist Circumference Regain After Weight Loss

Although many individuals are able to achieve weight loss, maintaining this loss over time is challenging. We aimed to study whether genetic predisposition to general or abdominal obesity predicts weight regain after weight loss. We examined the associations between genetic risk scores for higher BMI and higher waist-to-hip ratio adjusted for BMI (WHRadjBMI) with changes in weight and waist circumference up to 3 years after a 1-year weight loss program in participants (n = 822 women, n = 593 men) from the Look AHEAD (Action for Health in Diabetes) study who had lost ≥3% of their initial weight. Genetic predisposition to higher BMI or WHRadjBMI was not associated with weight regain after weight loss. However, the WHRadjBMI genetic score did predict an increase in waist circumference independent of weight change. To conclude, a genetic predisposition to higher WHRadjBMI predicts an increase in abdominal obesity after weight loss, whereas genetic predisposition to higher BMI is not predictive of weight regain. These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain.

ARTICLE HIGHLIGHTS

Nearly all individuals who intentionally lose weight experience weight regain. Individuals with a higher genetic risk for abdominal adiposity experience increased regain in waist circumference after weight loss. Genetic predisposition to higher BMI does not predict weight regain after weight loss.

Psychological resilience in older adults with type 2 diabetes from the Look AHEAD Trial

BACKGROUND

There is growing interest in identifying factors associated with healthy aging. This cross-sectional study evaluated associations of psychological resilience with factors associated with aging in older adults with type 2 diabetes mellitus (T2DM).

METHODS

Participants were 3199 adults (72.2 ± 6.2 years of age, 61% female, 61% White, body mass index [BMI] = 34.2 ± 8.2 kg/m2 ) with T2DM enrolled in Look AHEAD (a multi-site randomized clinical trial comparing an intensive lifestyle intervention for weight loss to diabetes education and support). Participants were followed observationally after the 10-year intervention was discontinued. The following items were assessed approximately 14.4 years post-randomization in a cross-sectional analysis: Brief Resilience Scale; overnight hospitalizations in past year; physical functioning measured objectively (gait speed, grip strength) and via self-report (Pepper Assessment Tool for Disability; physical quality of life [QOL; SF-36]); a measure of phenotypic frailty based on having ≥3 of unintentional weight loss, low energy, slow gait, reduced grip strength, and physical inactivity. Depressive symptoms (PHQ-9) and mental QOL (SF-36) were also measured. Logistic/linear/multinomial regression was used to evaluate the association of variables with resilience adjusted for age, race/ethnicity, and gender.

RESULTS

Greater psychological resilience was associated with lower BMI, fewer hospitalizations, better physical functioning (i.e., lower self-reported disability, better physical QOL, faster gait speed, greater grip strength, lower likelihood of frailty), fewer depressive symptoms, and greater mental QOL (all p < 0.05). Psychological resilience moderated the relationship of number of hospitalizations in the past year with self-reported disability and grip strength.

CONCLUSIONS

Psychological resilience is associated with better physical function and QOL among older adults. Results should be interpreted cautiously given cross-sectional nature of analyses. Exploring the clinical benefits of resilience is consistent with efforts to shift the narrative on aging beyond "loss and decline" to highlight opportunities to facilitate healthy aging.

Impact of COVID-19 on life experiences reported by a diverse cohort of older adults with diabetes and obesity

OBJECTIVE

This study aimed to measure the impact of the COVID-19 pandemic on self-reported life experiences in older adults with diabetes and obesity.

METHODS

Participants were surveyed in 2020 regarding negative and positive impacts of the pandemic across domains of personal, social, and physical experiences. A cumulative negative risk index (a count of all reported negative impacts of 46 items) and a positive risk index (5 items) were characterized in relation to age, sex, race/ethnicity, BMI, and multimorbidity.

RESULTS

Response rate was high (2950/3193, 92%), average age was 76 years, 63% were women, and 39% were from underrepresented populations. Women reported more negative impacts than men (6.8 vs. 5.6; p < 0.001 [of 46 items]) as did persons with a greater multimorbidity index (p < 0.001). Participants reporting African American/Black race reported fewer negative impacts than White participants. Women also reported more positive impacts than men (1.9 vs. 1.6; p < 0.001 [of 5 items]).

CONCLUSIONS

Older adults with diabetes and obesity reported more positive impacts of the pandemic than negative impacts, relative to the number of positive (or negative) items presented. Some subgroups experienced greater negative impacts (e.g., for women, a greater multimorbidity index). Efforts to reestablish personal, social, and physical health after the pandemic could target certain groups.

Genetic Predictors of Change in Waist Circumference and Waist-to-Hip Ratio With Lifestyle Intervention: The Trans-NIH Consortium for Genetics of Weight Loss Response to Lifestyle Intervention

Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) associated with waist circumference (WC) and waist-to-hip ratio (WHR) adjusted for BMI (WCadjBMI and WHRadjBMI), but it remains unclear whether these SNPs relate to change in WCadjBMI or WHRadjBMI with lifestyle intervention for weight loss. We hypothesized that polygenic scores (PS) comprised of 59 SNPs previously associated with central adiposity would predict less of a reduction in WCadjBMI or WHRadjBMI at 8-10 weeks in two lifestyle intervention trials, NUGENOB and DiOGenes, and at 1 year in five lifestyle intervention trials, Look AHEAD, Diabetes Prevention Program, Diabetes Prevention Study, DIETFITS, and PREDIMED-Plus. One-SD higher PS related to a smaller 1-year change in WCadjBMI in the lifestyle intervention arms at year 1 and thus predicted poorer response (β = 0.007; SE = 0.003; P = 0.03) among White participants overall and in White men (β = 0.01; SE = 0.004; P = 0.01). At average weight loss, this amounted to 0.20-0.28 cm per SD. No significant findings emerged in White women or African American men for the 8-10-week outcomes or for WHRadjBMI. Findings were heterogeneous in African American women. These results indicate that polygenic risk estimated from these 59 SNPs relates to change in WCadjBMI with lifestyle intervention, but the effects are small and not of sufficient magnitude to be clinically significant.

Changes in the Prevalence of Symptoms of Depression, Loneliness, and Insomnia in U.S. Older Adults With Type 2 Diabetes During the COVID-19 Pandemic: The Look AHEAD Study

OBJECTIVE

To evaluate changes in the prevalence of depressive symptoms, loneliness, and insomnia among older adults with type 2 diabetes from 2016 to 2020 and to assess risk factors for these conditions including demographics, multimorbidity, BMI, treatment group, and pre-coronavirus 2019 (COVID-19) measure scores.

RESEARCH DESIGN AND METHODS

This was a prospective, observational study of participants from the Look AHEAD (Action for Health in Diabetes) cohort study. Data were from two assessments before COVID-19 (visit 1: April 2016-June 2018 and visit 2: February 2018-February 2020) and one assessment during COVID-19 (visit 3: July-December 2020). Surveys were administered to assess depressive symptoms, loneliness, and insomnia.

RESULTS

The study included 2829 adults (63.2% female, 60.6% White, mean [SD] age 75.6 [6.0] years). The prevalence of mild or greater depressive symptoms did not change significantly between the two pre-pandemic visits (P = 0.88) but increased significantly from pre- to during COVID-19 (19.3% at V2 to 30.4% at V3; P < 0.001). Higher odds of mild or greater depressive symptoms at V3 were associated with being female (adjusted odds ratio [OR] 1.4 [95% CI 1.1-1.7]), identifying as non-Hispanic White (OR 1.4 [95% CI 1.1-1.7]), having obesity (OR 1.3 [95% CI 1.0-1.5]), and reporting mild or greater depressive symptoms at V1 (OR 4.0 [95% CI 2.9-5.4]), V2 (OR 4.4 [95% CI 3.2-5.9]), or both visits (OR 13.4 [95% CI 9.7-18.4]). The prevalence of loneliness increased from 12.3% at V1 to 22.1% at V3 (P < 0.001), while the prevalence of insomnia remained stable across visits at 31.5-33.3%.

CONCLUSIONS

The prevalence of mild or greater depressive symptoms in older adults with diabetes was more than 1.6 times higher during COVID-19 than before the pandemic.

Does the impact of intensive lifestyle intervention on cognitive function vary depending baseline level of frailty? An ancillary study to the Action for Health in Diabetes (Look AHEAD) Trial

AIMS

To assess whether there is an opportune window when intensive lifestyle intervention (ILI) benefits cognitive function.

METHODS

Standardized cognitive assessments were collected following ≥8 years of either ILI or a control condition of diabetes support and education (DSE) in 3708 individuals, ages 45-76 years at enrollment, with type 2 diabetes and overweight or obesity. Frailty index (FI) scores were used to group individuals at baseline into tertiles according to their age-related health status. Linear models were used to describe intervention adherence and cognitive function, with interaction terms to examine the consistency of relationships among tertiles.

RESULTS

Worse baseline FI scores were associated with poorer subsequent performance in tests of attention, processing speed, and executive function. No differences in any measure of cognitive function were observed between intervention groups within any FI tertile (all p > 0.10). Among individuals with worse baseline FI scores, weight gain was associated with poorer global cognitive function among participants assigned to DSE. There was no association between weight changes and cognitive function among participants assigned to ILI.

CONCLUSIONS

Among adults with type 2 diabetes and overweight/obesity, we found no evidence that there is a window of opportunity based on FI when ILI benefits cognitive function.

Precision behavioral medicine: Implications of genetic and genomic discoveries for behavioral weight loss treatment

This article reviews the concept of precision behavioral medicine and the progress toward applying genetics and genomics as tools to optimize weight management intervention. We discuss genetic, epigenetic, and genomic markers, as well as interactions between genetics and the environment as they relate to obesity and behavioral weight loss to date. Recommendations for the conditions under which genetics and genomics could be incorporated to support clinical decision-making in behavioral weight loss are outlined and illustrative scenarios of how this approach could improve clinical outcomes are provided. It is concluded that there is not yet sufficient evidence to leverage genetics or genomics to aid the treatment of obesity but the foundations are being laid. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Change in Cardiometabolic Risk Factors Associated With Magnitude of Weight Regain 3 Years After a 1-Year Intensive Lifestyle Intervention in Type 2 Diabetes Mellitus: The Look AHEAD Trial

Background

Weight regain after weight loss is common. The impact on cardiometabolic risk factors is not well established.

Methods and Results

Publicly available data were analyzed from participants of the Look AHEAD (Action for Health in Diabetes) trial with ≥3% initial weight loss (n=1561) during a 1‐year intensive lifestyle intervention and with year 4 follow‐up data. Participants who regained (regainers) or maintained (maintainers) weight loss were defined with 5 dichotomized cut points (0%, 25%, 50%, 75%, and 100%) of percentage weight loss regained (weight change from years 1–4 as percentage of first year weight loss). Change in cardiometabolic risk factors after initial weight loss was compared in maintainers and regainers, after controlling for demographics, medications, and baseline and year 1 change in body mass index. The effect was assessed separately in participants with <10% and ≥10% initial weight loss, and women and men. Maintainers exhibited significant improvements to the cardiometabolic risk factors assessed compared with regainers. No weight regain cut point maximized risk difference between maintainers and regainers across risk factors or sex/initial weight loss subgroups. For many risk factors, allowing more regain as part of maintenance (increasing cut point) diminished the cardiometabolic benefit among maintainers.

Conclusions

Maintaining weight loss was better than regain for all risk factors. No single cut point maximized the risk difference between maintainers and regainers. Maintainers who kept off ≥75% of weight lost had the greatest benefit. These findings emphasize the importance of intervention programs focusing not only on weight loss but weight loss maintenance, given the adverse consequences of the latter.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00017953.

Effects of Cognitive Strategies on Neural Food Cue Reactivity in Adults with Overweight/Obesity

OBJECTIVE

Functional magnetic resonance imaging (fMRI) studies of obesity have revealed key roles for reward-related and inhibitory control-related activity in response to food cues. This study examines how cognitive strategies impact neural food cue reactivity.

METHODS

In a within-participants, block-design, fMRI paradigm, 30 participants (24 women; mean BMI = 31.8) used four mind-sets while viewing food: "distract" (cognitive behavioral therapy based), "allow" (acceptance and commitment therapy based), "later" (focusing on long-term negative consequences), and "now" (control; focusing on immediate rewards). Participants rated cravings by noting urges to eat on four-point Likert scales after each block.

RESULTS

Self-reported cravings significantly differed among all conditions (pairwise comparisons P < 0.05). Cravings were lowest when participants considered long-term consequences (LATER mind-set: 1.7 [SD 0.7]), were significantly higher when participants used the DISTRACT (1.9 [SD 0.7]) and ALLOW (2.3 [SD 0.9]) mind-sets, and were highest when participants used the NOW mind-set (3.2 [SD 0.7]). These behavioral differences were accompanied by differences in neural food cue reactivity. The LATER mind-set (long-term consequences) led to greater inhibitory-control activity in the dorsolateral prefrontal cortex. The cognitive behavioral therapy-based DISTRACT mind-set was associated with greater activity in executive function and reward-processing areas, whereas the ALLOW mind-set (acceptance and commitment therapy) elicited widespread activity in frontal, reward-processing, and default-mode regions.

CONCLUSIONS

Because focusing on negative long-term consequences led to the greatest decrease in cravings and increased inhibitory control, this may be a promising treatment strategy for obesity.

Weight gain prevention buffers the impact of CETP rs3764261 on high density lipoprotein cholesterol in young adulthood: The Study of Novel Approaches to Weight Gain Prevention (SNAP)

BACKGROUND AND AIMS

Two weight gain prevention strategies, one targeting small changes to diet and physical activity and a second targeting large changes, significantly reduced weight gain in young adulthood. We examined whether weight gain prevention blunts genetic risk for body weight increase and/or high density lipoprotein cholesterol (HDL-C) lowering over two years.

METHODS AND RESULTS

Participants were 524 male and female young adults (mean age = 28.2, SD = 4.3; mean BMI = 25.5, SD = 2.6). Obesity-related SNPs accounting for ≥ 0.04% of the variance were genotyped and combined into a genetic risk score. For HDL-C, SNPs within CETP, LIPC and FADS2 were genotyped. The obesity-related genetic risk score did not predict change in BMI independently or in interaction with treatment arm. However, consistent with the prior literature, each copy of the HDL-C risk, C, allele at CETP rs3764261 was associated with lower HDL-C at baseline. Moreover, significant interaction between SNP and treatment arm for change in HDL-C was observed (p = 0.02). In the control group, HDL-C change was dependent upon rs3764261 (p = 0.004) with C allele carriers showing a continued reduction in HDL-C. In contrast, within the two intervention groups, HDL-C increased on average with no differential effect of rs3764261 (p > 0.24). Notably, even among carriers of the CC genotype, small and large change arms were associated with increased HDL-C and the control arm a reduction (p = 0.013).

CONCLUSIONS

The C allele at CETP rs3764261 is a strong risk factor for low HDL-C in young adulthood but weight gain prevention may mitigate this risk. CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE: clinicaltrials.gov Identifier: NCT01183689, https://clinicaltrials.gov/.

The Effects of Experimental Manipulation of Sleep Duration on Neural Response to Food Cues

Despite growing literature on neural food cue responsivity in obesity, little is known about how the brain processes food cues following partial sleep deprivation and whether short sleep leads to changes similar to those observed in obesity. We used functional magnetic resonance imaging (fMRI) to test the hypothesis that short sleep leads to increased reward-related and decreased inhibitory control-related processing of food cues.In a within-subject design, 30 participants (22 female, mean age = 36.7 standard deviation = 10.8 years, body mass index range 20.4-40.7) completed four nights of 6 hours/night time-in-bed (TIB; short sleep) and four nights of 9 hours/night TIB (long sleep) in random counterbalanced order in their home environments. Following each sleep condition, participants completed an fMRI scan while viewing food and nonfood images.A priori region of interest analyses revealed increased activity to food in short versus long sleep in regions of reward processing (eg, nucleus accumbens/putamen) and sensory/motor signaling (ie, right paracentral lobule, an effect that was most pronounced in obese individuals). Contrary to the hypothesis, whole brain analyses indicated greater food cue responsivity during short sleep in an inhibitory control region (right inferior frontal gyrus) and ventral medial prefrontal cortex, which has been implicated in reward coding and decision-making (false discovery rate corrected q = 0.05).These findings suggest that sleep restriction leads to both greater reward and control processing in response to food cues. Future research is needed to understand the dynamic functional connectivity between these regions during short sleep and whether the interplay between these neural processes determines if one succumbs to food temptation.

Comparison among criteria to define successful weight-loss maintainers and regainers in the Action for Health in Diabetes (Look AHEAD) and Diabetes Prevention Program trials

Background: Given the low rates of successful weight maintenance after lifestyle-induced weight loss, it is critical to develop approaches that distinguish successful weight-loss maintainers from regainers.Objective: The aim of this study was to compare published categorization criteria that differentiate maintainers and regainers via quantitative agreement.Design: The study used publicly available data from Look AHEAD (Action for Health in Diabetes; n = 1791) and Diabetes Prevention Program (DPP; n = 613) participants with ≥3% initial weight loss after lifestyle interventions and 4-y follow-up data. Eight previously published criteria defining maintainers and regainers were compared with respect to number of participants and concordance via agreement statistics. Criteria were assessed separately among those with 3-9% and ≥10% initial weight loss.Results: Regainers had higher body weight at year 4 than did maintainers (mean difference range: 6.6-11.9 kg in Look AHEAD; 11.5-14.6 kg in DPP; P < 0.0001). Assessing concordance among criteria, agreement was dependent on initial weight loss. Among those with 3-9% initial weight loss in both cohorts, 9 of 28 comparisons were concordant (agreement ≥80%). Among those with ≥10% initial weight loss, 7 of 28 comparisons in Look AHEAD and 13 of 28 in the DPP were in high agreement. The definition of successful weight-loss maintenance "regaining ≤25% of initial weight loss during maintenance" showed high agreement with the most commonly used definition of "staying ≥10% below initial weight" among those with ≥10% initial weight loss (agreement: 85.0% in Look AHEAD; 87.4% in DPP). The same definition of ≤25% regain showed high agreement with the definition of staying ≥5% below initial weight among those with 3-9% initial weight loss (agreement: 91.6% in Look AHEAD; 90.5% in DPP).Conclusions: Although all of the criteria discriminated on the basis of weight loss, many showed low agreement, which limited cross-study comparisons. Among criteria with high agreement, the definition of successful weight maintenance "regaining ≤25% of initial weight loss during maintenance" is a preferred definition of success, given the realistic challenges of maintaining 100% weight loss and flexible application in populations with high initial weight-loss variations. This trial was registered at clinicaltrials.gov as NCT00017953 (Look AHEAD) and NCT00004992 (DPP).

Identifying the mechanisms through which behavioral weight-loss treatment improves food decision-making in obesity

OBJECTIVES

Behavioral weight loss (BWL) programs are the recommended treatment for obesity, yet it is unknown whether these programs change one's ability to use self-control in food choices and what specific mechanisms support such change. Using experimental economics methods, we investigated whether changes in dietary behavior in individuals with obesity following BWL are driven by one or more of the following potential mechanisms: changes in the perception of the 1) health or 2) taste of food items, and/or 3) shifting decision weights for health versus taste attributes. Therefore, we compared these mechanisms between obese participants and lifetime normal weight controls (NW) both before and after BWL.

METHODS

Females with obesity (N = 37, mean BMI = 33.2) completed a food choice task involving health ratings, taste ratings, and decision-making pre- and post-standard BWL intervention. NW controls (N = 30, BMI = 22.4) completed the same task.

RESULTS

Individuals with obesity exhibited increased self-control (selecting healthier, less tasty food choices) post-treatment. However, their rates of self-control remained significantly lower than NW. We found no differences in initial health perceptions across groups, and no changes with treatment. In contrast, taste ratings and the relative value of taste versus health decreased following treatment. Although, post-treatment participants continued to perceive unhealthy foods as tastier and used less self-control than NW controls, they showed significant improvements in these domains following a BWL intervention.

CONCLUSIONS

To help individuals improve dietary decisions, additional research is needed to determine how to make greater changes in taste preferences and/or the assignment of value to taste versus health attributes in food choices.

Effect of a Long-Term Intensive Lifestyle Intervention on Cognitive Function: Action for Health in Diabetes Study

OBJECTIVES

To assess whether randomization to 10 years of lifestyle intervention to induce and maintain weight loss improves cognitive function.

DESIGN

Randomized controlled clinical trial.

SETTING

Data obtained as part of the Action for Health in Diabetes (Look AHEAD) trial (NCT00017953) and Look AHEAD Continuation study (U01 DK057136-15).

PARTICIPANTS

Overweight and obese individuals with type 2 diabetes mellitus aged 45 to 76 (N = 3,751).

INTERVENTION

Intensive lifestyle intervention (ILI) for weight loss through reduced caloric intake and increased physical activity compared with a control condition of diabetes support and education (DSE).

MEASUREMENTS

Certified examiners who were masked to intervention assignment administered a standard battery of cognitive function tests (Modified Mini-Mental State Examination, Rey Auditory Verbal Learning Test, Digit Symbol Coding, Trail-Making Test, Modified Stroop Color-Word Test) to participants 10 to 13 years after enrollment.

RESULTS

Assignment to lifestyle intervention was not associated with significantly different overall (P = .10) or domain-specific (all P > .10) cognitive function than assignment to diabetes support and education. Results were fairly consistent across prespecified groups, but there was some evidence of trends for differential intervention effects showing modest harm in ILI in participants with greater body mass index and in individuals with a history of cardiovascular disease. Cognitive function was not associated with changes in weight or fitness (all P > .05).

CONCLUSION

A long-term behavioral weight loss intervention for overweight and obese adults with diabetes mellitus was not associated with cognitive benefit. Trial Registration clinicaltrials.gov Identifier: NCT00017953.

Genetic modifiers of cardiorespiratory fitness response to lifestyle intervention

PURPOSE

Numerous prospective studies indicate that improved cardiorespiratory fitness reduces type 2 diabetes risk and delays disease progression. We hypothesized that genetic variants modify fitness response to an intensive lifestyle intervention (ILI) in the Action for Health in Diabetes (Look AHEAD) randomized clinical trial, aimed to detect whether ILI will reduce cardiovascular events in overweight/obese subjects with type 2 diabetes compared with a standard of care.

METHODS

Polymorphisms in established fitness genes and in all loci assayed on the Illumina CARe iSelect chip were examined as predictors of change in MET level, estimated using a treadmill test, in response to a 1-yr intervention in 3899 participants.

RESULTS

We identified a significant signal in previously reported fitness-related gene RUNX1 that was associated with 1-yr METs response in ILI (0.19 ± 0.04 MET less improvement per minor allele copy; P = 1.9 × 10(-5)) and genotype-intervention interaction (P = 4.8 × 10(-3)). In the chipwide analysis, FKBP7 rs17225700 showed a significant association with ILI response among subjects not receiving beta-blocker medications (0.47 ± 0.09 METs less improvement; P = 5.3 × 10(-5)) and genotype-treatment interaction (P = 5.3 × 10(-7)). The Gene Relationships Among Implicated Loci pathway-based analysis identified connections between associated genes, including those influencing vascular tone, muscle contraction, cardiac energy substrate dynamics, and muscle protein synthesis.

CONCLUSIONS

This is the first study to identify genetic variants associated with fitness responses to a randomized lifestyle intervention in overweight/obese diabetic individuals. RUNX1 and FKBP7, involved in erythropoesis and muscle protein synthesis, respectively, are related to change in cardiorespiratory fitness in response to exercise.

FTO genotype and weight loss: systematic review and meta-analysis of 9563 individual participant data from eight randomised controlled trials

OBJECTIVE

 To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or drug based interventions in randomised controlled trials.

DESIGN

 Systematic review and random effects meta-analysis of individual participant data from randomised controlled trials.

DATA SOURCES

 Ovid Medline, Scopus, Embase, and Cochrane from inception to November 2015.

ELIGIBILITY CRITERIA FOR STUDY SELECTION

 Randomised controlled trials in overweight or obese adults reporting reduction in body mass index, body weight, or waist circumference by FTO genotype (rs9939609 or a proxy) after dietary, physical activity, or drug based interventions. Gene by treatment interaction models were fitted to individual participant data from all studies included in this review, using allele dose coding for genetic effects and a common set of covariates. Study level interactions were combined using random effect models. Metaregression and subgroup analysis were used to assess sources of study heterogeneity.

RESULTS

 We identified eight eligible randomised controlled trials for the systematic review and meta-analysis (n=9563). Overall, differential changes in body mass index, body weight, and waist circumference in response to weight loss intervention were not significantly different between FTO genotypes. Sensitivity analyses indicated that differential changes in body mass index, body weight, and waist circumference by FTO genotype did not differ by intervention type, intervention length, ethnicity, sample size, sex, and baseline body mass index and age category.

CONCLUSIONS

 We have observed that carriage of the FTO minor allele was not associated with differential change in adiposity after weight loss interventions. These findings show that individuals carrying the minor allele respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions.

SYSTEMATIC REVIEW REGISTRATION

 PROSPERO CRD42015015969.

Partial sleep deprivation impacts impulsive action but not impulsive decision-making

Sleep deprivation may lead to increased impulsivity, however, previous literature has focused on examining effects of total sleep deprivation (TSD) rather than the more common condition, partial sleep deprivation (PSD) or 'short sleep'. Moreover, it has been unclear whether PSD impacts impulse-related cognitive processes, and specifically if it differentially affects impulsive action versus impulsive decision-making. We sought to determine if short compared to long sleep (6 vs. 9h/night) impacts impulsive action via behavioral inhibition (Go/No-Go), and/or impulsive decision-making processes of risk taking (Balloon Analogue Risk Task [BART]) and preferences for immediate over delayed rewards (Delay Discounting). In a within-subject design, 34 participants (71% female, mean age=37.0years, SD=10.54) were assigned to four consecutive nights of 6h/night (short sleep) and 9h/night (long sleep) in their own home in random counterbalanced order. Sleep was measured via wrist-worn actigraphs to confirm adherence to the sleep schedules (mean short sleep=5.9h, SD=0.3; mean long sleep=8.6h, SD=0.3, p<0.001). The Go/No-Go, BART, and Delay Discounting tasks were completed following both sleep conditions. Participants had more inhibition errors on the Go/No-Go task after short (mean false alarms=19.79%, SD=14.51) versus long sleep (mean=15.97%, SD=9.51, p=0.039). This effect was strongest in participants reporting longer habitual time in bed (p=0.04). There were no differences in performance following long- versus short-sleep for either delay discounting or the BART (p's>0.4). Overall, these results indicate that four days of PSD diminishes behavioral inhibition abilities, but may not alter impulsive decision-making. These findings contribute to the emerging understanding of how partial sleep deprivation, currently an epidemic, impacts cognitive ability. Future research should continue to explore the connection between PSD and cognitive functions, and ways to minimize the occurrence and negative consequences of short sleep.

Real-time assessment of heart rate variability and loss of control eating in adolescent girls: A pilot study

OBJECTIVE

Studying physiologic underpinnings of loss-of-control (LOC) eating may inform its etiology and contribute to intervention efforts. We therefore examined temporal relationships between autonomic indices [heart rate (HR), heart rate variability (HRV)] and LOC-eating in the natural environment.

METHOD

For two days, adolescents (n = 17, 14.77 ± 1.55 years, BMI-Z 2.17 ± 0.48) with LOC-eating reported on LOC using an electronic device while HR and HRV were assessed continuously using Holter monitoring.

RESULTS

Higher HR and lower HRV in the 30-minutes before eating were significantly associated with LOC-eating overall (p's < 0.001) and at the within-participants level (p's < 0.001), but not at the between-participants level (p's > 0.44). Examined categorically, HR was significantly higher, and HRV significantly lower, prior to high-LOC compared to low-LOC episodes (p's < 0.001).

DISCUSSION

This pilot study suggests that LOC-eating may involve physiologic underpinnings. Additional research with larger samples is needed to further investigate this phenomenon.

NIH working group report-using genomic information to guide weight management: From universal to precision treatment

OBJECTIVE

Precision medicine utilizes genomic and other data to optimize and personalize treatment. Although more than 2,500 genetic tests are currently available, largely for extreme and/or rare phenotypes, the question remains whether this approach can be used for the treatment of common, complex conditions like obesity, inflammation, and insulin resistance, which underlie a host of metabolic diseases.

METHODS

This review, developed from a Trans-NIH Conference titled "Genes, Behaviors, and Response to Weight Loss Interventions," provides an overview of the state of genetic and genomic research in the area of weight change and identifies key areas for future research.

RESULTS

Although many loci have been identified that are associated with cross-sectional measures of obesity/body size, relatively little is known regarding the genes/loci that influence dynamic measures of weight change over time. Although successful short-term weight loss has been achieved using many different strategies, sustainable weight loss has proven elusive for many, and there are important gaps in our understanding of energy balance regulation.

CONCLUSIONS

Elucidating the molecular basis of variability in weight change has the potential to improve treatment outcomes and inform innovative approaches that can simultaneously take into account information from genomic and other sources in devising individualized treatment plans.

Genetic Predisposition to Weight Loss and Regain With Lifestyle Intervention: Analyses From the Diabetes Prevention Program and the Look AHEAD Randomized Controlled Trials

Clinically relevant weight loss is achievable through lifestyle modification, but unintentional weight regain is common. We investigated whether recently discovered genetic variants affect weight loss and/or weight regain during behavioral intervention. Participants at high-risk of type 2 diabetes (Diabetes Prevention Program [DPP]; N = 917/907 intervention/comparison) or with type 2 diabetes (Look AHEAD [Action for Health in Diabetes]; N = 2,014/1,892 intervention/comparison) were from two parallel arm (lifestyle vs. comparison) randomized controlled trials. The associations of 91 established obesity-predisposing loci with weight loss across 4 years and with weight regain across years 2-4 after a minimum of 3% weight loss were tested. Each copy of the minor G allele of MTIF3 rs1885988 was consistently associated with greater weight loss following lifestyle intervention over 4 years across the DPP and Look AHEAD. No such effect was observed across comparison arms, leading to a nominally significant single nucleotide polymorphism×treatment interaction (P = 4.3 × 10(-3)). However, this effect was not significant at a study-wise significance level (Bonferroni threshold P < 5.8 × 10(-4)). Most obesity-predisposing gene variants were not associated with weight loss or regain within the DPP and Look AHEAD trials, directly or via interactions with lifestyle.

Lifestyle Intervention for Weight Loss and Cardiometabolic Changes in the Setting of Glucokinase Regulatory Protein Inhibition: Glucokinase Regulatory Protein-Leu446Pro Variant in Look AHEAD

BACKGROUND

Glucokinase regulatory protein (GCKR) inhibitors offer a novel treatment approach for glucose control in diabetes mellitus; however, their cardiometabolic effects, particularly in relation to increased triglycerides and C-reactive protein (CRP) levels, are of concern. GCKR Leu446Pro is a common variant associated with reduced GCKR function, increased triglycerides, and CRP.

METHODS AND RESULTS

We investigated whether a 1-year intensive lifestyle intervention (ILI) for weight loss would avert the unfavorable cardiometabolic effects associated with GCKR Leu446Pro when compared with a diabetes mellitus support and education arm in overweight/obese individuals with type 2 diabetes mellitus with triglyceride (n=3214) and CRP (n=1411) data participating in a randomized lifestyle intervention study for weight loss, Action for Health in Diabetes Mellitus (Look AHEAD). Once demographics, medication use and baseline adiposity, and fitness were accounted for, ILI did not modify the baseline association of GCKR-Leu446Pro with elevated triglycerides (β±SE=0.067±0.013, P=1.5×10(-7) and β±SE=0.052±0.015, P=5×10(-4)) or with elevated CRP (β±SE=0.136±0.034, P=5.1×10(-5)and β±SE=0.903±0.038, P=0.015) in the overall sample and Non-Hispanic Whites, respectively. The lack of a protective effect from ILI at 1 year when compared with diabetes mellitus support and education (ILI versus diabetes mellitus support and education interaction for triglyceride and CRP change, respectively: P=0.64 and 0.37 in the overall sample; P=0.27 and 0.05 in Non-Hispanic Whites) persisted after additional adjustment for changes in adiposity and fitness.

CONCLUSIONS

Moderate improvements in adiposity and fitness with ILI did not mitigate the adverse cardiometabolic effects of GCKR inhibition in overweight/obese individuals with diabetes mellitus.

Genetic complexity of episodic memory: a twin approach to studies of aging

Episodic memory change is a central issue in cognitive aging, and understanding that process will require elucidation of its genetic underpinnings. A key limiting factor in genetically informed research on memory has been lack of attention to genetic and phenotypic complexity, as if "memory is memory" and all well-validated assessments are essentially equivalent. Here we applied multivariate twin models to data from late-middle-aged participants in the Vietnam Era Twin Study of Aging to examine the genetic architecture of 6 measures from 3 standard neuropsychological tests: the California Verbal Learning Test-2, and Wechsler Memory Scale-III Logical Memory (LM) and Visual Reproductions (VR). An advantage of the twin method is that it can estimate the extent to which latent genetic influences are shared or independent across different measures before knowing which specific genes are involved. The best-fitting model was a higher order common pathways model with a heritable higher order general episodic memory factor and three test-specific subfactors. More importantly, substantial genetic variance was accounted for by genetic influences that were specific to the latent LM and VR subfactors (28% and 30%, respectively) and independent of the general factor. Such unique genetic influences could partially account for replication failures. Moreover, if different genes influence different memory phenotypes, they could well have different age-related trajectories. This approach represents an important step toward providing critical information for all types of genetically informative studies of aging and memory.

A common variant in the CLDN7/ELP5 locus predicts adiponectin change with lifestyle intervention and improved fitness in obese individuals with diabetes

Overweight/obese individuals with Type 2 diabetes have low adiponectin levels, which may improve with lifestyle changes. We investigated whether genetic variants associated with adiponectin levels in genome-wide association studies (GWAS) would also be related with adiponectin changes in response to an intensive lifestyle intervention (ILI), potentially through mechanisms altering the adipose microenvironment via weight loss and/or improved cardiorespiratory fitness. Look AHEAD was a randomized trial comparing the cardiovascular benefits of ILI-induced weight loss and physical activity compared with diabetes support and education among overweight/obese individuals with Type 2 diabetes. In a subsample of Look AHEAD with adiponectin data and genetic consent (n=1,351), we evaluated the effects of 24 genetic variants, demonstrated by GWAS to be cross-sectionally associated with adiponectin, on adiponectin change 1-yr postintervention. We explored via mediational analyses whether any differential effects by treatment arm were occurring through weight loss and/or improved fitness. A variant, rs222857, in the CLDN7 locus, potentially associated with epithelial barrier integrity and tight junction physiology, and a putative cis expression quantitative trail locus for elongator acetyltransferase complex subunit 5 (ELP5), predicted adiponectin increases within ILI (log-adiponectin in overall sample per copy: β±SE=0.05±0.02, P=0.008; in non-Hispanic whites: 0.06±0.02, P=0.009). The favorable effects of rs222857 (minor allele frequency 45.5%) appeared to be mediated by mechanisms associated with improved fitness, and not weight loss. This is the first study to identify a genetic variant that modifies adiponectin response to lifestyle intervention in overweight/obese diabetic individuals.

Imputing observed blood pressure for antihypertensive treatment: impact on population and genetic analyses

BACKGROUND

Elevated blood pressure (BP), a heritable risk factor for many age-related disorders, is commonly investigated in population and genetic studies, but antihypertensive use can confound study results. Routine methods to adjust for antihypertensives may not sufficiently account for newer treatment protocols (i.e., combination or multiple drug therapy) found in contemporary cohorts.

METHODS

We refined an existing method to impute unmedicated BP in individuals on antihypertensives by incorporating new treatment trends. We assessed BP and antihypertensive use in male twins (n = 1,237) from the Vietnam Era Twin Study of Aging: 36% reported antihypertensive use; 52% of those treated were on multiple drugs.

RESULTS

Estimated heritability was 0.43 (95% confidence interval (CI) = 0.20-0.50) and 0.44 (95% CI = 0.22-0.61) for measured systolic BP (SBP) and diastolic BP (DBP), respectively. We imputed BP for antihypertensives by 3 approaches: (i) addition of a fixed value of 10/5mm Hg to measured SBP/DBP; (ii) incremented addition of mm Hg to BP based on number of medications; and (iii) a refined approach adding mm Hg based on antihypertensive drug class and ethnicity. The imputations did not significantly affect estimated heritability of BP. However, use of our most refined imputation method and other methods resulted in significantly increased phenotypic correlations between BP and body mass index, a trait known to be correlated with BP.

CONCLUSIONS

This study highlights the potential usefulness of applying a representative adjustment for medication use, such as by considering drug class, ethnicity, and the combination of drugs when assessing the relationship between BP and risk factors.

Interaction of APOE genotype and testosterone on episodic memory in middle-aged men

Age-related changes in testosterone are believed to be a key component of the processes that contribute to cognitive aging in men. The APOE-ε4 allele may interact with testosterone and moderate the hormone's association with cognition. The goals of the present study were to examine the degree to which free testosterone is associated with episodic memory in a community-based sample of middle-aged men, and examine the potential interaction between free testosterone and the APOE-ε4 allele. Data were used from 717 participants in the Vietnam Era Twin Study of Aging. Average age was 55.4 years (standard deviation = 2.5). Significant positive associations were observed between free testosterone level and verbal episodic memory, as well as a significant interaction between free testosterone and APOE-ε4 status. In ε4 carriers free testosterone was positively associated with verbal episodic memory performance (story recall), whereas no association was observed in ε4 noncarriers. Results support the hypothesis that APOE-ε4 status increases susceptibility to other risk factors, such as low testosterone, which may ultimately contribute to cognitive decline or dementia.

Associations of self-reported and actigraphy-assessed sleep characteristics with body mass index and waist circumference in adults: moderation by gender

OBJECTIVES

Self-reported sleep duration has been linked to body mass index (BMI) and waist circumference in previous work; however, data regarding if these associations are stronger in men or women have been mixed, and few studies have objectively measured sleep. We investigated self-reported and actigraphy-assessed sleep characteristics in relation to BMI and waist circumference and examined the extent to which these associations differ by gender.

DESIGN

Archived cross-sectional data collected from 2004 to 2006 from the National Survey of Midlife Development in the United States (MIDUS) Biomarkers Study were used. Participants included 1248 adults (43% men) who reported their habitual sleep duration, and a subset of participants (N=441; 40% men) who underwent seven nights of wrist actigraphy.

RESULTS

Self-reported total sleep time (TST), actigraphy-assessed TST, and actigraphy-assessed sleep efficiency (SE) were inversely associated with BMI in the full sample of both men and women. Gender moderated associations between actigraphy assessments of sleep and anthropometric variables; however, TST and SE were related to BMI and waist circumference in women only. Associations between sleep and waist circumference were independent of BMI.

CONCLUSIONS

Sleep duration and sleep continuity are associated with body weight and distribution of body fat, but these associations were stronger or were only present in women.

Human cardiovascular disease IBC chip-wide association with weight loss and weight regain in the look AHEAD trial

BACKGROUND/AIMS

The present study identified genetic predictors of weight change during behavioral weight loss treatment.

METHODS

Participants were 3,899 overweight/obese individuals with type 2 diabetes from Look AHEAD, a randomized controlled trial to determine the effects of intensive lifestyle intervention (ILI), including weight loss and physical activity, relative to diabetes support and education, on cardiovascular outcomes. Analyses focused on associations of single nucleotide polymorphisms (SNPs) on the Illumina CARe iSelect (IBC) chip (minor allele frequency >5%; n = 31,959) with weight change at year 1 and year 4, and weight regain at year 4, among individuals who lost ≥ 3% at year 1.

RESULTS

Two novel regions of significant chip-wide association with year-1 weight loss in ILI were identified (p < 2.96E-06). ABCB11 rs484066 was associated with 1.16 kg higher weight per minor allele at year 1, whereas TNFRSF11A, or RANK, rs17069904 was associated with 1.70 kg lower weight per allele at year 1.

CONCLUSIONS

This study, the largest to date on genetic predictors of weight loss and regain, indicates that SNPs within ABCB11, related to bile salt transfer, and TNFRSF11A, implicated in adipose tissue physiology, predict the magnitude of weight loss during behavioral intervention. These results provide new insights into potential biological mechanisms and may ultimately inform weight loss treatment.

Greater Food-Related Stroop Interference Following Behavioral Weight Loss Intervention

Objective

Individuals who have successfully lost and maintained weight have slower reaction times on food-related Stroop tasks, indicating greater cognitive interference to food stimuli compared to obese and normal weight individuals. It remains unclear whether this interference is a preexisting characteristic of weight loss maintainers or if food-interference changes in obese individuals as they lose weight.

Method

To examine potential changes in food-related interference, a food-Stroop paradigm was used to measure responses to food versus non-food words in 13 obese women before and after a 12-week behavioral weight loss program.

Results

Participants achieved a mean weight loss of 5.12 kg through the behavioral weight loss program. Their reaction time to food words became significantly slower (p<0.001) and they made significantly more errors (p<0.01) following treatment.

Discussion

These findings suggest that through behavioral weight loss treatment obese individuals experience increased interference toward food words, which may reflect increased salience of food-related cues. Future research is needed to determine whether increases in interference are related to better weight loss and maintenance.

Do genetic modifiers of high-density lipoprotein cholesterol and triglyceride levels also modify their response to a lifestyle intervention in the setting of obesity and type-2 diabetes mellitus?: The Action for Health in Diabetes (Look AHEAD) study

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) and triglycerides are cardiovascular risk factors susceptible to lifestyle behavior modification and genetics. We hypothesized that genetic variants identified by genome-wide association studies as associated with HDL-C or triglyceride levels modify 1-year treatment response to an intensive lifestyle intervention, relative to a usual care of diabetes mellitus support and education.

METHODS AND RESULTS

We evaluated 82 single-nucleotide polymorphisms, which represent 31 loci demonstrated by genome-wide association studies to be associated with HDL-C and triglycerides, in 3561 participants who consented for genetic studies and met eligibility criteria. Variants associated with higher baseline HDL-C levels, cholesterol ester transfer protein (CETP) rs3764261 and hepatic lipase (LIPC) rs8034802, were found to be associated with HDL-C increases with intensive lifestyle intervention (P=0.0038 and 0.013, respectively) and had nominally significant treatment interactions (P=0.047 and 0.046, respectively). The fatty acid desaturase-2 rs1535 variant, associated with low baseline HDL-C (P=0.017), was associated with HDL-C increases with intensive lifestyle intervention (0.0037) and had a nominal treatment interaction (P=0.035). Apolipoprotein B (rs693) and LIPC (rs8034802) single-nucleotide polymorphisms showed nominally significant associations with HDL-C and triglyceride changes with intensive lifestyle intervention and a treatment interaction (P<0.05). Phosphatidylglycerophosphate synthase-1 single-nucleotide polymorphisms (rs4082919) showed the most significant triglyceride treatment interaction in the full cohort (P=0.0009).

CONCLUSIONS

This is the first study to identify genetic variants modifying lipid responses to a randomized lifestyle behavior intervention in overweight or obese individuals with diabetes mellitus. The effects of genetic factors on lipid changes may differ from the effects on baseline lipids and are modifiable by behavioral intervention.

Contributions of body mass index and exercise habits on inflammatory markers: a cohort study of middle-aged adults living in the USA

OBJECTIVES

Determine whether body mass index (BMI) and physical activity (PA) above, at or below MET minute per week (MMW) levels recommended in the 2008 Physical Activity Guidelines interact or have additive effects on interleukin (IL)-6, C reactive protein (CRP), fibrinogen, interleukin6 (IL-6) soluble receptor (IL-6sr), soluble E-selectin and soluble intracellular adhesion molecule (sICAM)-1.

DESIGN

Archived cohort data (n=1254, age 54.5±11.7 year, BMI 29.8±6.6 kg/m(2)) from the National Survey of Midlife Development in the USA (MIDUS) Biomarkers Study were analysed for concentrations of inflammatory markers using general linear models. MMW was defined as no regular exercise, <500 MMW, 500-1000 MMW, >1000 MMW and BMI was defined as <25, 25-29.9, ≥30 kg/m(2). Analyses were adjusted for age, sex, smoking and relevant medication use.

SETTING

Respondents reported to three centres to complete questionnaires and provide blood samples.

PARTICIPANTS

Participants were men and women currently enroled in the MIDUS Biomarker Project (n=1254, 93% non-Hispanic white, average age 54.5 years).

PRIMARY OUTCOME MEASURES

Concentration of serum IL-6, CRP, fibrinogen, IL-6sr, sE-selectin and sICAM.

RESULTS

Significant interactions were found between BMI and MMW for CRP and sICAM-1 (p<0.05). CRP in overweight individuals was similar to that in obese individuals when no PA was reported, but it was similar to normal weight when any level of regular PA was reported. sICAM-1 was differentially lower in obese individuals who reported >1000 MMW compared to obese individuals reporting less exercise.

CONCLUSIONS

The association of exercise with CRP and sICAM-1 differed by BMI, suggesting that regular exercise may buffer weight-associated elevations in CRP in overweight individuals while higher levels of exercise may be necessary to reduce sICAM-1 or CRP in obese individuals.

Reduced memory in fat mass and obesity-associated allele carriers among older adults with cardiovascular disease

BACKGROUND

Much attention has been paid to the prevalence and predisposition of the fat mass and obesity-associated (FTO) gene to obesity, although only a few studies have characterized the extent to which this affects cognitive function. This study examined differences between risk allele carriers (i.e. FTO-AC/AA) and non-carriers (i.e. FTO-CC) on indices of attention/executive function/psychomotor speed, memory, language, and visual-spatial ability in a sample of older patients with cardiovascular disease.

METHODS

We recruited 120 older adults from an outpatient cardiology clinic who underwent blood draw and completed neuropsychological testing. Participants were classified into two groups: one for those who were homozygous for the non-risk-conferring allele (i.e. FTO-CC) (n= 49) and the other for those who had at least one copy of the obesity risk-conferring A allele (i.e. FTO-AC/AA) (n= 71).

RESULTS

Mancova analyses adjusting for age and years of education revealed the FTO-AC/AA group performed significantly worse on indices of memory (λ= 0.94, F(2, 115) = 3.58, P= 0.03, partial η(2) = 0.06). Follow-up tests revealed a significant effect for the FTO-AC/AA group, relative to the non-carrier group, on encoding (i.e. California Verbal Learning Test Total Learning) and California Verbal Learning Test long-delay free recall (P < 0.05). No such differences between FTO carriers and non-carriers emerged on tests of attention/executive function/psychomotor speed, language, or visual-spatial ability (P > 0.05 for all).

CONCLUSIONS

These findings suggest that the FTO risk allele is associated with reduced memory performance, particularly on aspects of memory encoding and delayed recall. To elucidate underlying mechanisms, these findings will need to be replicated in larger samples that utilize neuroimaging.

Brain response to food stimulation in obese, normal weight, and successful weight loss maintainers

As many people struggle with maintenance of weight loss, the study of successful weight loss maintainers (SWLM) can yield important insights into factors contributing to weight loss maintenance. However, little research has examined how SWLM differ from people who are obese or normal weight (NW) in brain response to orosensory stimulation. The goal of this study was to determine if SWLM exhibit different brain responses to orosensory stimulation. Brain response to 1-min orosensory stimulation with a lemon lollipop was assessed using functional magnetic resonance imaging among 49 participants, including SWLM (n = 17), NW (n = 18), and obese (n = 14) controls. Significant brain responses were observed in nine brain regions, including the bilateral insula, left inferior frontal gyrus, left putamen, and other sensory regions. All regions also exhibited significant attenuation of this response over 1 min. The SWLM exhibited greater response compared with the other groups in all brain regions. Findings suggest that the response to orosensory stimulation peaks within 40 s and attenuates significantly between 40 and 60 s in regions associated with sensation, reward, and inhibitory control. Greater reactivity among the SWLM suggests that greater sensory reactivity to orosensory stimulation, increased anticipated reward, and subsequently greater inhibitory processing are associated with weight loss maintenance.

Factor structure underlying components of allostatic load

Allostatic load is a commonly used metric of health risk based on the hypothesis that recurrent exposure to environmental demands (e.g., stress) engenders a progressive dysregulation of multiple physiological systems. Prominent indicators of response to environmental challenges, such as stress-related hormones, sympatho-vagal balance, or inflammatory cytokines, comprise primary allostatic mediators. Secondary mediators reflect ensuing biological alterations that accumulate over time and confer risk for clinical disease but overlap substantially with a second metric of health risk, the metabolic syndrome. Whether allostatic load mediators covary and thus warrant treatment as a unitary construct remains to be established and, in particular, the relation of allostatic load parameters to the metabolic syndrome requires elucidation. Here, we employ confirmatory factor analysis to test: 1) whether a single common factor underlies variation in physiological systems associated with allostatic load; and 2) whether allostatic load parameters continue to load on a single common factor if a second factor representing the metabolic syndrome is also modeled. Participants were 645 adults from Allegheny County, PA (30–54 years old, 82% non-Hispanic white, 52% female) who were free of confounding medications. Model fitting supported a single, second-order factor underlying variance in the allostatic load components available in this study (metabolic, inflammatory and vagal measures). Further, this common factor reflecting covariation among allostatic load components persisted when a latent factor representing metabolic syndrome facets was conjointly modeled. Overall, this study provides novel evidence that the modeled allostatic load components do share common variance as hypothesized. Moreover, the common variance suggests the existence of statistical coherence above and beyond that attributable to the metabolic syndrome.

Ambulatory blood pressure and the metabolic syndrome in normotensive and untreated hypertensive men

BACKGROUND

Components of the metabolic syndrome are typically intercorrelated in epidemiologic studies and, when combined, predict type 2 diabetes and cardiovascular diseases. However, it remains unclear whether a single construct underlies the various components and which of the components are most closely associated with the underlying syndrome. Here, we use our confirmatory factor analytic model of the metabolic syndrome to examine the extent to which measures of ambulatory blood pressure, reflecting blood pressure variability throughout the day and night, may strengthen the association between blood pressure and the other components of the syndrome.

METHODS

Participants were a community sample of 358 men (248 with hypertension), ages 40-70, not receiving antihypertensive medications. Confirmatory factor analysis was employed to examine model fit and the strength of association between clinic and ambulatory blood pressure and the metabolic syndrome.

RESULTS

The blood pressure factor loaded significantly on the underlying metabolic syndrome but the strength of association was not as great (loading = 0.34, p < 0.01) as those observed for the obesity, insulin resistance and lipid factors. The factor loadings for the ambulatory measures (awake loading = 0.19; sleep loading = 0.16, p values < 0.01) were significant but smaller in magnitude than the loadings for clinic blood pressure.

CONCLUSIONS

Both clinic and ambulatory measures of blood pressure are significantly associated with the underlying metabolic syndrome using confirmatory factor analytic methods. However, the strength of association appears greater for the clinic measures relative to the ambulatory measures in this study.

Association of type 2 diabetes susceptibility loci with one-year weight loss in the look AHEAD clinical trial

The importance of lifestyle intervention for the prevention and treatment of type 2 diabetes (T2D) has been underscored by the limited benefit of pharmacologic therapies. We sought to determine whether genetic variants that contribute to T2D risk modify the response of weight and waist circumference to an intensive lifestyle intervention (ILI) in patients with obesity and T2D. Look AHEAD (Action for Health in Diabetes) is a randomized clinical trial comparing an ILI with a control condition on the risk of cardiovascular disease in overweight adults with T2D. We analyzed 28 single-nucleotide polymorphisms (SNPs) at/near 17 T2D-susceptibility genes in 3,903 consented participants. We genetically characterized the cohort by assessing whether T2D-susceptibility loci were overrepresented compared with a nondiabetic community-based cohort (N = 1,016). We evaluated the association of individual variants and a composite genetic risk score (GRS) with anthropometric traits at baseline and after 1-year of intervention. Look AHEAD subjects carried more T2D-susceptibility alleles than the control population. At baseline, TCF7L2 risk alleles and the highest GRS were associated with lower BMI and waist circumference. Nominally significant genotype-by-intervention interactions were detected for 1-year change in waist circumference with JAZF1, MTNR1B, and IRS1, and BMI with JAZF1. Highest GRS was associated with a greater reduction in waist circumference at year 1, although the variance in change attributable to the GRS was small. This study shows that the genetic burden associated with T2D risk does not undermine the effect of lifestyle intervention and suggests the existence of additional genomic regions, distinct from the T2D-susceptibility loci, which may enhance or mitigate weight loss.

Obesity susceptibility loci and dietary intake in the Look AHEAD Trial

BACKGROUND

Genome-wide association studies (GWAS) have identified consistent associations with obesity. However, the mechanisms remain unclear.

OBJECTIVE

The objective was to determine the association between obesity susceptibility loci and dietary intake.

DESIGN

The association of GWAS-identified obesity risk alleles (FTO, MC4R, SH2B1, BDNF, INSIG2, TNNI3K, NISCH-STAB1, MTIF3, MAP2K5, QPCTL/GIPR, and PPARG) with dietary intake, measured through food-frequency questionnaires, was investigated in 2075 participants from the Look AHEAD (Action for Health in Diabetes) clinical trial. We adjusted for age, sex, population stratification, and study site.

RESULTS

Obesity risk alleles at FTO rs1421085 significantly predicted more eating episodes per day (P = 0.001)-an effect that persisted after adjustment for body weight (P = 0.004). Risk variants within BDNF were significantly associated with more servings from the dairy product and the meat, eggs, nuts, and beans food groups (P ≤ 0.004). The risk allele at SH2B1 rs4788099 was significantly associated with more servings of dairy products (P = 0.001), whereas the risk allele at TNNI3K rs1514176 was significantly associated with a lower percentage of energy from protein (P = 0.002).

CONCLUSION

These findings suggest that obesity risk loci may affect the pattern and content of food consumption among overweight or obese individuals with type 2 diabetes. The Look AHEAD Genetic Ancillary Study was registered at clinicaltrials.gov as NCT01270763 and the Look AHEAD study as NCT00017953.

Cortical thickness of the cognitive control network in obesity and successful weight loss maintenance: a preliminary MRI study

Cortical thickness of the cognitive control network was contrasted between obese (OB), successful weight loss maintainers (SWLM), and lean individuals. OB individuals had significant thinning, most notably in the anterior cingulate and posterior parietal cortices. SWLM individuals exhibited trends towards thicker cortex than OB individuals, which may be important in future studies.

Genetic predictors of weight loss and weight regain after intensive lifestyle modification, metformin treatment, or standard care in the Diabetes Prevention Program

OBJECTIVE

We tested genetic associations with weight loss and weight regain in the Diabetes Prevention Program, a randomized controlled trial of weight loss-inducing interventions (lifestyle and metformin) versus placebo.

RESEARCH DESIGN AND METHODS

Sixteen obesity-predisposing single nucleotide polymorphisms (SNPs) were tested for association with short-term (baseline to 6 months) and long-term (baseline to 2 years) weight loss and weight regain (6 months to study end).

RESULTS

Irrespective of treatment, the Ala12 allele at PPARG associated with short- and long-term weight loss (-0.63 and -0.93 kg/allele, P ≤ 0.005, respectively). Gene-treatment interactions were observed for short-term (LYPLAL1 rs2605100, P(lifestyle*SNP) = 0.032; GNPDA2 rs10938397, P(lifestyle*SNP) = 0.016; MTCH2 rs10838738, P(lifestyle*SNP) = 0.022) and long-term (NEGR1 rs2815752, P(metformin*SNP) = 0.028; FTO rs9939609, P(lifestyle*SNP) = 0.044) weight loss. Three of 16 SNPs were associated with weight regain (NEGR1 rs2815752, BDNF rs6265, PPARG rs1801282), irrespective of treatment. TMEM18 rs6548238 and KTCD15 rs29941 showed treatment-specific effects (P(lifestyle*SNP) < 0.05).

CONCLUSIONS

Genetic information may help identify people who require additional support to maintain reduced weight after clinical intervention.

Effects of social contact and zygosity on 21-y weight change in male twins

BACKGROUND

Recent evidence indicates that social contact is related to similarities in weight gain over time. However, no studies have examined this effect in a twin design, in which genetic and other environmental effects can also be estimated.

OBJECTIVE

We determined whether the frequency of social contact is associated with similarity in weight change from young adulthood (mean age: 20 y) to middle age (mean age: 41 y) in twins and quantified the percentage of variance in weight change attributable to social contact, genetic factors, and other environmental influences.

DESIGN

Participants were 1966 monozygotic and 1529 dizygotic male twin pairs from the Vietnam-Era Twin Registry. Regression models tested whether frequency of social contact and zygosity predicted twin pair similarity in body mass index (BMI) change and weight change. Twin modeling was used to partition the percentage variance attributable to social contact, genetic, and other environmental effects.

RESULTS

Twins gained an average of 3.99 BMI units, or 13.23 kg (29.11 lb), over 21 y. In regression models, both zygosity (P < 0.001) and degree of social contact (P < 0.02) significantly predicted twin pair similarity in BMI change. In twin modeling, social contact between twins contributed 16% of the variance in BMI change (P < 0.001), whereas genetic factors contributed 42%, with no effect of additional shared environmental factors (1%). Similar results were obtained for weight change.

CONCLUSION

Frequency of social contact significantly predicted twin pair similarity in BMI and weight change over 21 y, independent of zygosity and other shared environmental influences.

TCF7L2 polymorphism, weight loss and proinsulin:insulin ratio in the diabetes prevention program

Aims

TCF7L2 variants have been associated with type 2 diabetes, body mass index (BMI), and deficits in proinsulin processing and insulin secretion. Here we sought to test whether these effects were apparent in high-risk individuals and modify treatment responses.

Methods

We examined the potential role of the TCF7L2 rs7903146 variant in predicting resistance to weight loss or a lack of improvement of proinsulin processing during 2.5-years of follow-up participants (N = 2,994) from the Diabetes Prevention Program (DPP), a randomized controlled trial designed to prevent or delay diabetes in high-risk adults.

Results

We observed no difference in the degree of weight loss by rs7903146 genotypes. However, the T allele (conferring higher risk of diabetes) at rs7903146 was associated with higher fasting proinsulin at baseline (P<0.001), higher baseline proinsulin∶insulin ratio (p<0.0001) and increased proinsulin∶insulin ratio over a median of 2.5 years of follow-up (P = 0.003). Effects were comparable across treatment arms.

Conclusions

The combination of a lack of impact of the TCF7L2 genotypes on the ability to lose weight, but the presence of a consistent effect on the proinsulin∶insulin ratio over the course of DPP, suggests that high-risk genotype carriers at this locus can successfully lose weight to counter diabetes risk despite persistent deficits in insulin production.

Cognitive interference from food cues in weight loss maintainers, normal weight, and obese individuals

Much attention has been paid to the behavioral characteristics of successful weight loss maintenance, but less is known about the cognitive processes that underlie this process. The purpose of this study was to investigate cognitive interference from food-related cues in long-term weight loss maintainers (WLM; N = 15) as compared with normal weight (NW; N = 19) and obese (OB; N = 14) controls. A Food Stroop paradigm was used to determine whether successful WLM differed from controls in both the speed and accuracy of color naming words for low-calorie and high-calorie foods. A significant group × condition interaction for reaction time was observed (P = 0.04). In post hoc analyses, no significant differences in reaction time across the three groups were observed for the low-calorie foods (P = 0.66). However, for the high-calorie foods, WLM showed a significantly slower reaction time than the NW (0.04) and OB (0.009) groups (885 ± 17.6, 834 ± 15.8, 816 ± 18.3 ms, respectively). No significant group differences were seen for number of correct trials in 45 s (P = 0.12). The differential interference among WLM did not appear to generalize to other types of distracters (i.e., nonfood). Overall, findings from this study suggest that WLM differ from OB and NW controls in their cognitive responses to high-calorie food cues. Future research is needed to better understand why this bias exists and whether and how interventions can change cognitive processes to better facilitate long-term weight control.

Systemic inflammation and the metabolic syndrome among middle-aged community volunteers

The metabolic syndrome is conceptualized as a clustering of risk factors--including insulin resistance, dyslipidemia, central adiposity, and elevated blood pressure (BP)--that increase the risk for cardiovascular disease and type 2 diabetes mellitus. Recent evidence suggests that markers of systemic inflammation may be included in the definition of the syndrome and play some role in its pathogenesis. In this study, we use a statistical modeling technique, confirmatory factor analysis, to evaluate relationships of systemic inflammation, as measured by plasma concentrations of C-reactive protein and interleukin-6, with the component factors of the metabolic syndrome (insulin resistance, dyslipidemia, central adiposity, and elevated BP) and to examine whether inflammation is a potential common pathway linking established components to the full syndrome. Subjects were 645 community volunteers aged 30 to 54 years (48% male, 82% European American, 18% African American). Consistent with existing literature, structural equation modeling adjusting for age, sex, and race confirmed a higher-order common factor underlying the covariation of insulin resistance, dyslipidemia, adiposity, and BP. Inflammation was positively associated with this common factor, accounting for 54% of its variance and partially mediating statistical aggregation of the component factors comprising the metabolic syndrome. These results were particularly strong for adiposity, raising the possibility that inflammatory processes stimulated by intraabdominal adipose tissue contribute to the development of the metabolic syndrome. The inclusion of inflammatory markers in the clinical definition of metabolic syndrome seems warranted and may improve prognostic assessment of risk of type 2 diabetes mellitus and cardiovascular disease.

Salivary habituation to food stimuli in successful weight loss maintainers, obese and normal-weight adults

OBJECTIVE

Research shows that slower habituation of salivary responses to food stimuli is related to greater energy intake and that obese (Ob) individuals habituate slower than those of normal weight (NW). No study has examined habituation rates in weight loss maintainers (WLMs) who have reduced from obese to normal weight, relative to those who are Ob or NW.

DESIGN

Salivation to two baseline water trials and 10 lemon-flavored lollipop trials were studied in 14 WLMs, 15 Ob and 18 NW individuals comparable in age, gender and ethnicity. Linear mixed models were used to compare WLMs with Ob and NW groups.

RESULTS

Salivation in the WLM and NW groups decreased significantly (for both P <0.005) across trials, indicative of habituation. Salivary responses in the Ob group did not habituate (P=0.46). When compared with Ob group, WLMs showed a quicker reduction in salivation (P<0.05). WLM and NW groups did not differ in habituation rate (P=0.49).

CONCLUSIONS

WLMs have habituation rates that are comparable to NW individuals without previous history of obesity, and show quicker habituation than those who are currently obese. These results suggest that physiological responses to food may 'normalize' with successful weight loss maintenance.

Differential functional magnetic resonance imaging response to food pictures in successful weight-loss maintainers relative to normal-weight and obese controls

BACKGROUND

Prior research indicates that successful weight-loss maintainers (SWLs) work harder than people of normal weight to maintain their weight loss, including greater dietary restriction of fat and higher physical activity levels. However, little work to date has examined how SWLs differ biologically from normal-weight (NW) and obese controls.

OBJECTIVE

The objective was to compare the brain responses of SWLs to food pictures with those of NW and obese controls.

DESIGN

Blood oxygen level-dependent responses to high- and low-energy food pictures were measured in 18 NW controls, 16 obese controls, and 17 SWLs.

RESULTS

Group differences were identified in 4 regions, which indicated significant change in activation in response to the food pictures. SWLs showed greater activation in the left superior frontal region and right middle temporal region than did NW and obese controls-a pattern of results confirmed in exploratory voxel-wise analyses. Obese controls also showed greater activation in a bilateral precentral region.

CONCLUSIONS

These results suggest that SWLs show greater activation in frontal regions and primary and secondary visual cortices-a pattern consistent with greater inhibitory control in response to food cues and greater visual attention to the food cues. A greater engagement of inhibitory control regions in response to food cues as well as a greater monitoring of foods may promote control of food intake and successful weight-loss maintenance.

Genetic predictors of depressive symptoms in cardiac patients

Numerous studies suggest that the prevalence of depression is greater among cardiac patients than in the general population. However, little attention has been paid to the possibility of genetic contributions to depressive symptoms in cardiac patients. We conducted a candidate gene study focusing on genes related to inflammation, platelet aggregation, endothelial function and omega-3 fatty acid metabolism as predictors of depressive symptoms among 977 participants with established cardiovascular disease. Results suggested that genetic variation related to endothelial dysfunction is predictive of depressive symptoms and that endothelial dysfunction may be a novel mechanism contributing to depressive symptoms among cardiac patients.