Dynamic model of procrastination

Procrastination is the notorious tendency to postpone work for tomorrow. This paper presents a formal model of procrastination based on expectations and prospect theory, which differs signficantly from the prevalent model of O’Donoghue and Rabin. Subject is assumed to work on a task for distant reward which depends on the number of periods actually spent working, where the subject faces varying op- portunity costs of working each period before the deadline. In order to assess a hypothesis that procrastination is an evolved and stable habit, the model is rendered dynamic in that past decisions and circumstances affect the present. The model is first explored via qualitative analysis and simulations are performed to further reveal its functionality.procrastination, dynamic inconsistency, intertemporal choice, prospect theory, hyperbolic discounting, expectations

Dynamic model of procrastination

Procrastination is the notorious tendency to postpone work for tomorrow. This paper presents a formal model of procrastination based on expectations and prospect theory, which differs signficantly from the prevalent model of O’Donoghue and Rabin. Subject is assumed to work on a task for distant reward which depends on the number of periods actually spent working, where the subject faces varying op- portunity costs of working each period before the deadline. In order to assess a hypothesis that procrastination is an evolved and stable habit, the model is rendered dynamic in that past decisions and circumstances affect the present. The model is first explored via qualitative analysis and simulations are performed to further reveal its functionality

Dynamic model of procrastination

Procrastination is the notorious tendency to postpone work for tomorrow. This paper presents a formal model of procrastination based on expectations and prospect theory, which differs signficantly from the prevalent model of O’Donoghue and Rabin. Subject is assumed to work on a task for distant reward which depends on the number of periods actually spent working, where the subject faces varying op- portunity costs of working each period before the deadline. In order to assess a hypothesis that procrastination is an evolved and stable habit, the model is rendered dynamic in that past decisions and circumstances affect the present. The model is first explored via qualitative analysis and simulations are performed to further reveal its functionality

Association between depressive symptom clusters and food attentional bias

Background The mechanisms underlying the depression-obesity relationship are unclear. Food attentional bias (FAB) represents one candidate mechanism that has not been examined. We evaluated the hypothesis that greater depressive symptoms are associated with increased FAB. Method Participants were 89 normal weight or overweight adults (mean age = 21.2 ± 4.0 years, 53% female, 33% non-white, mean body mass index in kg/m2 = 21.9 ± 1.8 for normal weight; 27.2 ± 1.5 for overweight). Total, somatic, and cognitive-affective depressive symptom scores were computed from the Patient Health Questionnaire-8 (PHQ-8). FAB scores were calculated using reaction times (RT) and eye-tracking (ET) direction and duration measures for a food visual probe task. Age, gender, race/ethnicity, and body fat percent were covariates. Results Only PHQ-8 somatic symptoms were positively associated with RT-measured FAB (β = 0.23, p = .04). The relationship between somatic symptoms and ET direction (β = 0.18, p = .17) and duration (β = 0.23, p = .08) FAB indices were of similar magnitude but were not significant. Somatic symptoms accounted for 5% of the variance in RT-measured FAB. PHQ-8 total and cognitive-affective symptoms were unrelated to all FAB indices (ps ≥ 0.09). Conclusions Only greater somatic symptoms of depression were linked to food attentional bias as measured using reaction time. Well-powered prospective studies should examine whether this bias replicates, particularly for eye-tracking measures, and whether it partially mediates the depression-to-obesity relationship

Somatic Symptoms, but Not Nonsomatic Symptoms, of Depression are Associated with Insulin Resistance: National Health and Nutrition Examination Survey (NHANES) 2005-2010

poster abstractWhile there is a well-established link between depression and type 2 diabetes, depressive symptoms have received little attention in this literature. To begin to address this gap, we examined relationships among the somatic and nonsomatic symptoms of depression and insulin resistance, which is involved in the development of type 2 diabetes. Participants were 4,834 adults (mean age = 44.3 years, 50% female, 19% African American, 20% Mexican American) who participated in the 2005-2010 waves of NHANES – a survey of a large representative sample of the U.S. population. Participants with the following conditions were excluded: diabetes, cardiovascular disease, liver disease, kidney disease, or pregnancy. Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-9), and somatic and nonsomatic subscales were derived based on confirmatory factor analysis. Our index of insulin resistance was the homeostatic model assessment (HOMA) score, which we computed from fasting plasma glucose and insulin levels. Separate regression analyses (adjusted for age, sex, race-ethnicity, education, BMI, and NHANES sample design) demonstrated positive relationships between PHQ-9 total (B=0.04, SEB=0.01, p<0.0001), somatic (B=0.07, SEB=0.02, p=0.0004), and nonsomatic (B=0.06, SEB=0.02, p=0.0004) scores and HOMA score. When the subscales were entered simultaneously into a regression model, the somatic score (B=0.05, SEB=0.02, p=0.03), but not the nonsomatic score (B=0.03, SEB=0.02, p=0.06), remained associated with HOMA score. A significant interaction was found for race-ethnicity, and further analyses demonstrate that the somatic symptoms of depression are only significantly associated with HOMA among Caucasians (B=0.07, SEB=0.02, p=0.02). Our cross-sectional findings suggest that the relationship between depression and insulin resistance may be driven by the somatic symptoms of depression and that this relationship may only be present only occur in Caucasians. The findings suggest that Caucasian adults with the somatic symptoms of depression may be at an elevated risk of type 2 diabetes

Diet composition as a candidate mechanism underlying the depression-to-obesity association: the CARDIA study

Indiana University-Purdue University Indianapolis (IUPUI)People with depression are at elevated risk for future obesity; however, little is known about the potential mechanistic role of diet composition in this association. The aims of the present study were: (1) to examine depressive symptom severity as a predictor of 13-year change in seven diet composition factors over time, (2) to test 13-year change in diet composition factors as mediators of the association between depressive symptom severity and 13-year change in adiposity, and (3) to explore whether the Aim 2 mediation models are moderated by sex and race. Participants were 2,449 non-Hispanic Black and White adults who participated in the 1990, 1992, and 2005 years of the CARDIA study (mean baseline age = 35 years, 54% women, 56% non-Hispanic Black, mean baseline waist circumference = 84.0 cm, mean change in waist circumference = 8.3 cm). Depressive symptoms were assessed in 1990 using the Center for Epidemiologic Studies-Depression Scale (CES-D). Waist circumference and seven diet composition factors were assessed in 1992 and 2005. Diet composition factors included intake of total energy, saturated fatty acid, monounsaturated fatty acid, polyunsaturated fatty acid, fiber, sugar, and protein. PROCESS bootstrapping analyses were used to test for mediation and moderated mediation (see Figure 1 for the conceptual model). All models included adjustment for age; sex; race; education; prevalent and incident cardiovascular disease, diabetes, and cancer; incident pregnancy; and 13-year change in physical activity. Greater baseline CES-D Total predicted greater 13-year increases in waist circumference (path c β = 0.032, p = .006). In separate models, there was a trend for greater baseline depressive symptoms predicting 13-year increases in total energy intake (path a β = 0.040, p = .054), and greater baseline depressive symptoms predicted 13-year increases in protein intake (path a β = 0.059, p = .004) and fiber intake (path a β = 0.040, p = .0496). Depressive symptoms were unrelated to 13-year changes in intake of the other diet composition factors of saturated fatty acid, monounsaturated fatty acid, polyunsaturated fatty acid, and sugar (all ps ≥ .129). Mediation models revealed that 13-year change in total energy intake and protein intake partially mediated the association between baseline depressive symptoms and 13-year change in waist circumference (total energy intake indirect effect = 0.001, 95% CI=0.0001-0.004; protein intake indirect effect = 0.002, 95% CI=0.0004-0.005); mediation was not observed for the other diet composition factors. Exploratory moderated mediation models detected a significant interaction for CES-D Total by sex predicting 13-year change protein intake only (Index of moderated mediation=0.004, 95%CI=0.001-0.010). All other tests of moderated mediation were non-significant (95% CIs included zero). Analyses stratified by sex revealed that CES-D Total was more strongly associated with 13-year increases protein intake in men (β = 0.011, p=.004) than in women (β = 0.027, p = .246). Findings from this larger, longitudinal, epidemiologic study suggest that the prospective relationship between depression and future obesity risk may be explained, in part, by intake of certain diet composition factors. Advancing the understanding of the relationship between depression and diet changes will inform clinical efforts to prevent or manage depression-related obesity

Depressive Symptoms and Weight Loss Behaviors in U.S. Adults

Objective We sought to determine whether depressive symptoms are associated with attempting to lose weight and engaging in weight loss behaviors in a large, diverse sample of adults representative of the U.S. population. Methods Respondents were 23,106 adults, free of cardiovascular disease and diabetes, who participated in the 2005–2014 years of the National Health and Nutrition Examination Survey (NHANES). Depressive symptoms were measured using the Patient Health Questionnaire-9 (PHQ-9), and weight loss variables were obtained from a Weight History Questionnaire. Results PHQ-9 total was not associated with attempting to lose weight in the past year (OR = 1.03, 95%CI = 1.00–1.06, p = 0.074; n = 23,106). Among respondents who attempted to lose weight (n = 9582), PHQ-9 total was associated with a lower odds of exercising (OR = 0.84, 95%CI = 0.79–0.89, p < 0.001) and a greater odds of skipping meals (OR = 1.31, 95%CI = 1.22–1.41, p < 0.001), eating diet foods/products (OR = 1.16, 95%CI = 1.08–1.24, p < 0.001), eating less food (OR = 1.09, 95%CI = 1.04–1.15, p < 0.001), taking non-prescription supplements (OR = 1.31, 95%CI = 1.23–1.41, p < 0.001), taking prescription diet pills (OR = 1.28, 95%CI = 1.10–1.49, p = 0.001), and taking laxatives/vomiting (OR = 1.55, 95%CI = 1.28–1.88, p < 0.001). Conclusions Although depressive symptoms were not associated with attempting to lose weight in the past year, adults who attempted to lose weight tended to employ potentially ineffective/unhealthy weight loss behaviors and avoid effective behaviors. This pattern of behaviors may be another mechanism that explains the excess risk of obesity in depressed adults and may be a modifiable target for future interventions. Given the cross-sectional nature of this study, reverse causality is a possibility. Future studies should investigate the prospective associations between depressive symptoms and weight loss behaviors

Differences in Mexican Americans’ Prevalence of Chronic Pain and Co-Occurring Analgesic Medication and Substance Use Relative to Non-Hispanic White and Black Americans: Results from NHANES 1999–2004

Objective. Little is known about the burgeoning Mexican American (MA) population’s pain experience. Methods. Using 1999–2004 National Health and Nutrition Examination Survey (NHANES) data, prevalence of chronic pain, analgesic medication use, and substance use were examined among MA, non-Hispanic White (NHW), and non-Hispanic Black (NHB) respondents. Logistic and linear regression models examined racial/ethnic differences in: 1) chronic pain prevalence among all respondents, 2) location and number of pain sites among respondents with chronic pain, and 3) analgesic medication and substance use among respondents with chronic pain. Results. Compared to NHWs and NHBs, MAs were less likely to report any chronic pain. Among respondents with chronic pain, MAs had higher odds of reporting headache, abdominal pain, and a greater number of pain sites than NHWs. Compared to NHWs, MAs with chronic pain had lower odds of reporting past-month analgesic medication and COX-2 inhibitor use. MAs with chronic pain had lower odds of being a current cigarette smoker and heavy alcohol drinker but had similar street drug/cocaine use relative to NHWs. Conclusions. Results suggest that: 1) MAs are less likely to develop chronic pain than NHWs, 2) MAs with chronic pain report greater headache and abdominal pain than NHWs, and 3) MAs with chronic pain are less likely to use analgesic medications and other substances compared to NHWs. These results suggest that providers should consider taking extra time to discuss analgesic medications with MAs. Future investigations should examine reasons underlying these racial/ethnic differences in chronic pain, as well as differences in the use of other substances, such as marijuana

Depressive Symptoms are Associated with Poor Adherence to Some Lifestyle but not Medication Recommendations to Prevent Cardiovascular Disease: National Health and Nutrition Examination Survey (NHANES) 2005-2010

poster abstractDepression has been linked to poor medical adherence; however, most studies have involved persons with preexisting conditions, such as cardiovascular disease (CVD). Our aim was to examine relationships between depressive symptoms and adherence to medication and lifestyle recommendations intended to prevent CVD in a community sample. We selected adults ≥18 years (53%-56% female, 47%-52% non-white) with a history of hypertension and/or hypercholesterolemia, but free of CVD, who participated in 2005-2010 waves of NHANES – a survey of a large probability sample representative of the U.S. population. The Patient Health Questionnaire-9 (PHQ-9) was used to assess depressive symptoms (converted to z-scores). The NHANES Blood Pressure and Cholesterol questionnaire was used to assess self-reported adherence to five medication and lifestyle recommendations: take antihypertensive medication (N=3313), take lipid-lowering medication (N=2266), control/lose weight (N=2177), eat fewer high fat/cholesterol foods (N=2924), and increase physical activity (N=2540). Logistic regression models (adjusting for age, sex, race-ethnicity, education, body mass, diabetes, smoking status, daily alcohol intake and NHANES sample design) revealed that a 1-SD increase in PHQ-9 total score was associated with a 14% lower likelihood of adherence to the control/lose weight recommendation (OR=0.86, 95% CI: 0.75-0.98, p=.02) and a 25% lower likelihood of adherence to the increase physical activity recommendation (OR=0.75, 95% CI: 0.65-0.86, p<.001). PHQ-9 total score was not associated with the likelihood of adherence to antihypertensive medication (OR, 0.93, 95% CI: 0.82-1.05, p=0.21), lipid-lowering medication (OR=0.99, 95% CI: 0.86-1.14, p=0.90), or eat fewer high fat/cholesterol foods recommendations (OR=0.94, 95% CI: 0.82-1.08, p=0.40). Adherence rates for depressed verses nondepressed adults to the control/lose weight recommendation were 75% and 85% and the increase physical activity recommendation were 63% and 79%, respectively. Our findings suggest that poor adherence to weight and activity recommendations, but not medication and diet recommendations, may partially explain the excess CVD risk of depressed persons

Associations between immigrant status and pharmacological treatments for diabetes in U.S. adults

Objectives: Although treatment disparities in diabetes have been documented along racial/ethnic lines, it is unclear if immigrant groups in the United States experience similar treatment disparities. Our objective was to determine whether immigrant status is associated with differences in pharmacological treatment of diabetes in a nationally representative sample of adults with diabetes. We were specifically interested in differences in treatment with oral hypoglycemic agents (OHA) and insulin. Method: Respondents were 2,260 adults from National Health and Nutritional Examination Survey (NHANES) 2003–2012 with a self-reported diabetes diagnosis. Immigrant status was indicated by birth within (U.S.-born) or outside (foreign-born) the 50 U.S. States or Washington, DC. Multinomial logistic regression analyses examined associations between immigrant status and (a) treatment with OHAs only and (b) treatment with insulin only or insulin and OHA combination therapy, using no treatment as the reference group. Results: Adjusting for demographics, diabetes severity and duration, cardiovascular disease (CVD), and CVD risk factors, being foreign-born versus U.S.-born was not associated with treatment with OHAs only (odds ratio [OR] = 1.59; 95% confidence interval [CI] [0.97, 2.60]). However, being foreign-born was associated with decreased odds (OR = 0.53; 95% CI [0.28, 0.99]) of treatment with insulin. Conclusions: Pharmacological treatment of diabetes differs along immigrant status lines. To understand these findings, studies capturing the processes underlying treatment differences in diabetes among immigrants are needed. Findings raise the possibility that integrating information about a patient’s immigrant status, in addition to racial/ethnic identity, may be an important component of culturally sensitive diabetes care