Biomedical subjects

Neal Doran

Publications and source records attributed to Neal Doran.

6 recordsLinked to original sources

PubMed2006

Effect of tryptophan depletion on smokers and nonsmokers with and without history of major depression.

BACKGROUND: Serotonergic dysregulation is posited to contribute to comorbidity between nicotine dependence and depression. We tested whether acute tryptophan depletion (ATD) triggers depressive symptoms in euthymic, unmedicated smokers and nonsmokers with and without history of major depressive disorder (MDD). METHODS: Acute tryptophan depletion and taste-matched placebo challenges were administered double-blind in counter-balanced order. Participants were four groups of volunteers hypothesized to be of increasing affective vulnerability as follows: nonsmokers lacking recurrent personal and familial history of MDD (n = 20), smokers lacking recurrent personal and familial history of MDD (n = 21), nonsmokers with history of recurrent personal and familial MDD (n = 16), and smokers with recurrent personal and familial history of MDD (n = 16). Depression, dysphoric mood, and plasma amino acids were measured at baseline and around the time of peak depletion. RESULTS: Depressive symptom response to ATD was heightened significantly by history of MDD (p < .001) and marginally by smoking (p = .09). Smoking seemed to magnify the ATD response of those with a history of MDD (effect size = .63) but had no effect on those without MDD history (effect size = .06). CONCLUSIONS: Depressive symptom response to serotonergic challenge is exaggerated in unmedicated, euthymic adults with recurrent personal and familial vulnerability to MDD, perhaps especially if they also smoke.

Adolescent↗

PubMed2006

Impulsivity and the reinforcing value of cigarette smoking.

The present study tested the hypothesis that impulsivity would predict perceptions of positive and negative reinforcement from smoking. The secondary hypothesis was that the relationship between impulsivity and smoking reinforcement expectations would be mediated by the character trait of self-directedness. College students (n=202) who reported smoking cigarettes participated in the survey study. Hierarchical regression analyses confirmed that impulsivity predicted expectations about positive (beta=.22, p=.001) and negative (beta=.25, p=.001) reinforcement from smoking. These relationships were also mediated by self-directedness. Results suggest that impulsive smokers in the early stages of dependence may smoke because they expect smoking to be extremely pleasurable as well as to help dispel bouts with negative affect. Furthermore, their elevated expectations about smoking may be related to difficulties adapting to challenging environments and working toward long-term goals.

Adult↗

PubMed2006

Elevated positive mood: a mixed blessing for abstinence.

The present study, a secondary analysis of published data, assessed (a) the influence of initial positive mood (PM) on smoking cessation and (b) whether smokers low in PM benefited from fluoxetine versus placebo for cessation. Euthymic adult smokers (N = 103) received 10 weeks of cessation treatment. Analyses showed a Time x PM interaction, indicating that higher baseline PM predicted decreased abstinence during treatment but increased abstinence afterward, mediated by time to dropout. Dichotomous initial PM interacted with drug, suggesting a benefit of fluoxetine for low-PM smokers. Results indicate that lower pretreatment PM may inhibit long-term cessation. Smokers with lower baseline PM may benefit from treatment that increases PM.

Adolescent↗

PubMed2006

Effect of nicotine on negative affect among more impulsive smokers.

In the present study, the authors tested the hypothesis that nicotine would provide greater relief from negative affect for more impulsive smokers than for less impulsive smokers. Euthymic adult smokers (N=70) participated in 2 laboratory sessions, during which they underwent a negative mood induction (music + autobiographical memory), then smoked either a nicotinized or de-nicotinized cigarette. Mixed-effects regression yielded a significant Impulsivity x Condition (nicotinized vs. de-nicotinized) x Time interaction. Simple effects analyses showed that heightened impulsivity predicted greater negative affect relief after smoking a nicotinized cigarette but not after smoking a de-nicotinized cigarette. These data suggest that nicotine may be a disproportionately powerful negative reinforcer for highly impulsive smokers, promoting higher levels of nicotine dependence and inhibiting smoking cessation.

Adolescent↗

PubMed2004

Randomized controlled trial for behavioral smoking and weight control treatment: effect of concurrent versus sequential intervention.

The authors compared simultaneous versus sequential approaches to multiple health behavior change in diet, exercise, and cigarette smoking. Female regular smokers (N = 315) randomized to 3 conditions received 16 weeks of behavioral smoking treatment, quit smoking at Week 5, and were followed for 9 months after quit date. Weight management was omitted for control and was added to the 1st 8 weeks for early diet (ED) and the final 8 weeks for late diet (LD). ED lacked lasting effect on weight gain, whereas LD initially lacked but gradually acquired a weight-suppression effect that stabilized (p = .004). Behavioral weight control did not undermine smoking cessation and, when initiated after the smoking quit date, slowed the rate of weight gain, supporting a sequential approach.

Adult↗

PubMed2004

Impulsivity and smoking relapse.

Previous research has shown that elevated trait-impulsivity heightens the risk for initiating tobacco use and indicates that nicotine may be disproportionately rewarding for more impulsive persons. However, the influence of impulsivity on the ability to maintain nicotine abstinence has not been studied. The present study tested the hypothesis that a higher level of trait-impulsivity would predict a more rapid relapse to smoking following 48 hr of nicotine abstinence. Participants were euthymic, regular smokers (N=45), with a history of at least one major depressive episode, who participated in a paid smoking cessation study with biological challenge (tryptophan depletion). Treatment involved a 1-day skills training workshop followed by 48 hr of bioverified abstinence and weekly follow-up for 1 month. Regression analyses indicated that elevated impulsivity predicted shorter time to relapse following the workshop after controlling for treatment condition, baseline nicotine dependence, and age (beta=-.39, R(2) change=.147, p=.011). Greater impulsivity predicted more rapid relapse to smoking, which mediational analyses indicated could not be explained by positive affect, negative affect, or craving. Findings suggest a need to identify alternative mechanisms to explain impulsive smokers' increased difficulty in maintaining abstinence and to develop targeted treatments that address the special needs of smokers high in impulsivity.

Adolescent↗