Behavioral effects of plasma tryptophan depletion in aggressive and nonaggressive men

Serotonin (5-HT) neurotransmission deficits have been implicated in impulsive aggression. A Trp-free beverage of amino acids competitively inhibits Trp uptake into the brain for 5-HT synthesis and also lowers endogenous plasma Trp for several hours. This has worsened mood and/or increased aggressive behavior, especially in hostile persons or those with histories of depression. In 24 community-recruited men (12 each with and without significant aggression histories), aggressive and impulsive behavior in the laboratory was assessed before and after plasma Trp depletion and Trp loading. In the aggression model, subjects were provoked by periodic subtractions of participation earnings, and these subtractions were blamed on a ficitious other participant. Aggression was measured as the responses the subject made to subtract money from his antagonist. Impulsiveness was operationalized as: (1) the choice of smaller reward after a shorter delay over having to wait longer to receive a larger reward, and (2) “false alarm” commission errors in a modified Continuous Performance Task, which represent a failure to inhibit responding to stimuli similar (but not identical) to target stimuli. Finally, plasma cortisol and Trp were measured under each condition immediately following a aggression testing session when subjects were highly provoked. I hypothesized that 5-HT may tonically modulate (inhibit) the hypothalmnic-pituitary-adrenal stress response, such that Trp depletion may enhance the cortisol response to high provocation in aggressive men. ^ Trp depletion had no effect in the laboratory tasks purported to measure impulsive behavior, and failed to cause increases in aggressive behavior under low provocation conditions. Under higher provocation, however, aggressive responses we re elevated under Trp-depleted conditions relative to Trp-loaded conditions in aggressive men, whereas the reverse was true in nonaggressive men. Cortisol levels nonsignificantly paralled the group differences in aggression under Trp-depleted and Trp-loaded conditions. Aggressive men achieved lower plasma Trp levels after Trp loading than did nonaggressive men, possibly due to heavy alcohol use histories. The high post-loading plasma Trp levels in nonaggressive men tended also to correlate with their aggressive responding rates, due perhaps to increases in other psychoactive Trp metabolites. ^

Evaluation of a wellness program at a large private sector petrochemical company in Texas

The study purpose was to analyze the effects Integrated Health Solutions (IHS), an employee wellness program that has been implemented for one year on the corporate campus of a major private sector petrochemical company in Houston, TX, has on employee health. ^ Chronic diseases are the leading causes of morbidity and mortality in the United States and are the most preventable of all health problems. The costs of chronic diseases in the working-age adult population include not only health problems and a decrease in quality of life, but also an increase the cost of health care and costs to businesses and employers, both directly and indirectly. These emerging costs to employers as well as the fact that adults now spend the majority of waking hours at the office have increased the interest in worksite health promotion programs that address many of the behavioral factors that lead to chronic conditions. Therefore, implementing and evaluating programs that are aimed at promoting health and decreasing the prevalence of chronic diseases at worksites is very important. ^ Data came from existing data that were collected by IHS staff during employee biometric screenings at the company in 2010 and 2011. Data from employees who participated in screenings in both 2010 and 2011 were grouped into a cohort by IHS staff. ^ One-tailed t-tests were conducted to determine if there were significant improvements in the biometric measures of body fat percentage, BMI, waist circumference, systolic and diastolic blood pressures, total, HDL, and LDL cholesterol levels, triglycerides, blood glucose levels, and cardiac risk ratios. Sensitivity analysis was conducted to determine if there were differences in program outcomes when stratified by age, gender, job type, and time between screenings. ^ Mean differences for the variables from 2010 to 2011 were small and not always in the desired direction for health improvement indicators. Through conducting t-tests, it was found that there were significant improvements in HDL, cardiac risk ratio, and glucose levels. There were significant increases in cholesterol, LDL, and diastolic blood pressures. For the IHS program, it appears that gender, job type, and time between screenings were possible modifiers of program effectiveness. When program outcome measures were stratified by these factors, results suggest that corporate employees had better outcomes than field employees, males had better outcomes overall than females, and more positive program effects were seen for employees with less time between their two screenings. ^ Recommendations for the program based on the results include ensuring validity of instruments and initial and periodic training of measurement procedures and equipment handling, using normative data or benchmarks to decrease chances for biased estimates of program effectiveness, measuring behaviors as well as biometric and physiologic statuses and changes, and collecting level of engagement data.^

Relationships of impulsivity and physical fighting history to alcohol -induced aggression in women

Research suggests women respond to the aggression-inducing effects of alcohol in a manner similar to men. Highly aggressive men are more prone to alcohol-induced aggression, but this relationship is less clear for women. This study examined whether alcohol consumption would differentially affect laboratory-measured aggression in a sample of aggressive and non-aggressive women and how those differences might be related to components of impulsive behavior. In 39 women recruited from the community (two groups: with and without histories of physical fighting) ages 21–40, laboratory aggressive behavior was assessed following placebo and 0.80 g/kg alcohol consumption (all women experienced both conditions). Baseline laboratory impulsive behavior of three impulsivity models was later assessed in the same women. In the aggression model (PSAP), participants were provoked by periodic subtractions of money, which were blamed on a fictitious partner. Aggression was operationalized as the responses the participant made to subtract money from that partner. The three components of impulsivity that were tested included: (1) response initiation (IMT/DMT), premature responses made prior to the completion of stimulus processing, (2) response inhibition (GoStop), a failure to inhibit an already initiated response, and (3) consequence sensitivity (SKIP and TCIP), the choice for a smaller-sooner reward over a larger-later reward. I hypothesized that, compared to women with no history of physical fighting, women with a history of physical fighting would exhibit higher rates of alcohol-induced laboratory aggression and higher rates of baseline impulsive responding (particularly for the IMT/DMT), which would also be related to the alcohol-induced increases aggression. Consistent with studies in men, the aggressive women showed strong associations between laboratory aggression and self-report measures, while the non-aggressive women did not. However, unlike men, following alcohol consumption it was the non-aggressive women's laboratory aggression that was related to their self-reports of aggression and impulsivity. Additionally, response initiation measures of impulsivity distinguished the two groups, while response inhibition and consequence sensitivity measures did not; commission error rates on the IMT/DMT were higher in the aggressive women compared to the non-aggressive women. Regression analyses of the behavioral measures showed no relationship between the aggression and impulsivity performance of the two groups. These results suggest that the behavioral (and potentially biological) mechanism underlying aggressive behavior of women is different than that of men. ^