Biomedical subjects

Michele Pergadia

Publications and source records attributed to Michele Pergadia.

3 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↗

PubMed2004

Double-blind trial of the effects of tryptophan depletion on depression and cerebral blood flow in smokers.

Studies of clinically depressed patients have documented left frontal lobe hypoactivity. Smokers also show an increased prevalence of depression and evidence that nicotine normalizes qEEG indices of left frontal lobe activity. Tryptophan depletion (TD) has been shown to increase negative mood in smokers, particularly those with recurrent depression. Thus, in smokers, we expected that increased depression during TD would be associated with decreased cerebral blood flow, specifically in the left frontal lobe. Hamilton depression scores and relative regional cerebral blood flow (rCBF) were measured with SPECT using (99m)Tc-hexamethylpropyleneamineoxime in seven smokers after TD and after a control procedure. Decreased bilateral cerebral blood flow to the inferior frontal (IF) lobe following TD relative to placebo was associated with increased depressed mood (r= -.653, P<.05). Among smokers, a decrease in brain serotonin is associated with increased depressed mood and with focal bilateral decreases in IF activity. Chronic nicotine exposure appears to be associated with cortical responses suggestive of depressive vulnerability.

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↗