Nicotine and fluoxetine induce arousing effects on sleep–wake cycle in antidepressive doses: A possible mechanism of antidepressant-like effects of nicotine

Suicidality among South Brazilian tobacco growers

OBJECTIVE

To assess prevalence of suicidal ideation and suicide attempt among South Brazilian tobacco growers and to analyze the associated factors related to the suicidal ideation.

METHODS

A cross-sectional study was conducted in 2011 with a random sample of 2469 tobacco growers in São Lourenço do Sul/RS. Suicidal ideation was characterized by the question "Has the thought of ending your life been on your mind?". Suicide attempt was assessed by the question "Have you ever tried to kill yourself?". Investigation of factors associated with suicidal ideation was done by means of Poisson regression.

RESULTS

Prevalence of suicidal ideation and suicide attempt was 2.5 % and 1.2 % respectively. In the adjusted analysis, suicidal ideation was associated with being female, older age, moderate participation in religious activities and difficulty in paying debts. Those who worked in activities that required inadequate postures (hunched over or other forced positions), as well as farmers who performed 6-9 pesticide-related tasks demonstrated greater risk of suicidal ideation. Regarding health conditions, medical diagnosis of asthma, chronic low back pain, number of lifetime green tobacco sickness episodes and lifetime pesticide poisoning were positively associated with suicidal ideation.

CONCLUSION

Suicidal thoughts and attempts are relevant mental health problems among tobacco growers. Reducing pesticide use, as well as exposure to nicotine and improving socio-economic conditions, can reduce suicidal ideation and improve the mental health of exposed workers.

Tobacco smoke exposure and sleep: estimating the association of urinary cotinine with sleep quality

INTRODUCTION

A majority of studies on tobacco smoke exposure and sleep quality have relied on self-reported smoking, resulting in potential exposure misclassification and biases related to self-report. The objective of this study was to investigate associations between urinary cotinine, a biological marker of tobacco smoke exposure, and sleep quality measures, including sleep duration, sleep continuity or efficiency, sleep satisfaction and alertness during normal waking hours.

METHODS

Using data on a national sample of 10 806 adults (aged 18-79 years) from the Canadian Health Measures Survey (2007-2013), we performed binary logistic regression analyses to estimate associations between urinary cotinine concentrations and sleep quality measures, while controlling for potential confounders. Additionally, we performed ordinal logistic regression to assess the association between urinary cotinine concentrations and increased number of sleep problems.

RESULTS

Overall, 28.7% of adult Canadian survey respondents had urinary cotinine concentrations above the limit of detection (LOD), nd the prevalence of each sleep problem ranged from 5.5% to 35.6%. Elevated urinary cotinine concentrations (quartile 4 vs. <LOD) were associated with significantly higher odds of short or long sleep duration (OR = 1.41; 95% CI: 1.02-1.95; p-trend = .021), trouble falling or staying asleep (OR = 1.71; 95% CI: 1.28-2.27; p-trend = .003), sleep dissatisfaction (OR = 1.87; 95% CI: 1.21-2.89; p-trend = .011), and increased number of sleep problems (OR = 1.64; 95% CI: 1.19-2.26; p-trend = .001). Stronger associations were observed among females compared to males.

CONCLUSION

Using a biological marker of tobacco smoke exposure, our study contributes to the body of literature of toxic environmental exposures on sleep quality by supporting an association between tobacco smoke exposure and poorer sleep quality. To address the limitations of a cross-sectional study design and to better assess the temporality of tobacco smoke exposure and sleep quality, longitudinal studies are recommended.

Carbachol and Nicotine in Prefrontal Cortex Have Differential Effects on Sleep-Wake States

The role of the brainstem cholinergic system in the regulation of sleep-wake states has been studied extensively but relatively little is known about the role of cholinergic mechanisms in prefrontal cortex in the regulation of sleep-wake states. In a recent study, we showed that prefrontal cholinergic stimulation in anesthetized rat can reverse the traits associated with anesthesia and restore a wake-like state, thereby providing evidence for a causal role for prefrontal cholinergic mechanisms in modulating level of arousal. However, the effect of increase in prefrontal cholinergic tone on spontaneous sleep-wake states has yet to be demonstrated. Therefore, in this study, we tested the hypothesis that delivery of cholinergic agonists - carbachol or nicotine - into prefrontal cortex of rat during slow wave sleep (SWS) would produce behavioral arousal and increase the time spent in wake state. We show that unilateral microinjection (200 nL) of carbachol (1 mM) or nicotine (100 mM) into prefrontal cortex during SWS decreased the latency to the onset of wake state (p = 0.03 for carbachol, p = 0.03 for nicotine) and increased the latency to the onset of rapid eye movement sleep (p = 0.008 for carbachol, p = 0.006 for nicotine). Although the infusion of 1 mM carbachol increased the time spent in wake state (p = 0.01) and decreased the time spent in SWS (p = 0.01), infusion of 10 or 100 mM nicotine did not produce any statistically significant change in sleep-wake architecture. These data demonstrate a differential role of prefrontal cholinergic receptors in modulating spontaneous sleep-wake states.

Efficacy and safety evaluation of citalopram and doxepin on sleep quality in comorbid insomnia and anxiety disorders

Anxiety disorders are frequently comorbid with insomnia, and sleep disturbance in patients with anxiety disorders is the most common complaint. Antidepressants can affect sleep quality; however, their effect in patients with comorbid insomnia and anxiety disorders is unclear. The aim of the present study was to comprehensively evaluate the dose, treatment duration, treatment efficacy and safety of clinical citalopram and doxepin application in patients with comorbid insomnia and anxiety disorders. It was found that both citalopram (20 mg/day) and low-dose doxepin (12.5 mg/day) significantly improved sleep latency, duration and disturbances, as well as daytime dysfunction and the global Pittsburgh Sleep Quality Index during the 12-week treatment period. Notably, low-dose doxepin significantly improved sleep latency in patients after treatment for 8 and 12 weeks as compared with citalopram. It was further observed that both citalopram and low-dose doxepin improved anxiety. A significant and positive correlation was found between the improvement in the sleep quality and anxiety in the two treatment groups. Citalopram and low-dose doxepin both showed good efficacy and a low adverse reaction rate in the treated patients. These data support a potential application of citalopram and low-dose doxepin in the treatment of patients with comorbid insomnia and anxiety disorders.

Occupational exposure to pesticides, nicotine and minor psychiatric disorders among tobacco farmers in southern Brazil

INTRODUCTION

Exposure to pesticides has been associated with psychiatric problems among farm workers, although there is still controversy as to chemical types, intensity and forms of exposure that represent risk factors for neuropsychological problems. Furthermore, tobacco workers are exposed to dermal absorption of nicotine, although its effect on mental health has not yet been studied.

OBJECTIVES

To identify the prevalence of minor psychiatric disorders (MPD) among tobacco farmers and associated factors, paying special attention to pesticide and nicotine exposure.

METHODS

This is a cross-sectional study with a representative sample of tobacco growers, characterizing economic indicators of the farms, socio-demographic factors, lifestyle habits and occupational exposures. Multivariate analysis was performed using a hierarchical Poisson regression model.

RESULTS

A total of 2400 tobacco farmers were assessed and MPD prevalence was 12%. MPD was higher among women (PR 1.4), workers aged 40 or over, tenants/employees (PR 1.8) and those who reported having difficulty in paying debts (PR 2.0). Low socioeconomic status was inversely associated with MPD prevalence. Tasks involving dermal exposure to pesticides showed risk varying between 35% and 71%, whereas tobacco growers on farms using organophosphates had 50% more risk of MPD than those not exposed to this kind of pesticide. The number of pesticide poisoning and green tobacco sickness episodes showed linear association with MPD.

CONCLUSIONS

The study reinforces the evidence of the association between pesticide poisoning and mental health disorders. It also points to increased risk of MPD from low socioeconomic status, dermal pesticide exposure as well as from exposure to organophosphates. Furthermore, the study reveals intense nicotine exposure as a risk for tobacco farmers' mental health.

Depressive symptoms among heavy cigarette smokers: the influence of daily rate, gender, and race

INTRODUCTION

Cigarette smokers experience higher levels of depressive symptoms and are more likely to be diagnosed with depressive disorders than nonsmokers. To date, the nature of the smoking-depression relationship has not been adequately studied among heavy smokers, a group at elevated risk for poor health outcomes. In this study, we examined depressive symptom expression among heavy smokers while considering the moderating roles of smoking status, gender, and race. We also explored whether amount of tobacco usually consumed had an impact.

METHODS

We extracted data from a large, highly nicotine-dependent, nontreatment cigarette smoking study sample (N = 6,158). Participants who consented were screened for major exclusions, and they completed questionnaires.

RESULTS

Smokers reported a higher, clinically meaningful level of depressive symptoms relative to nonsmokers (27.3% of smokers vs. 12.5% of nonsmokers) scored above the clinical cutoff on the Center for Epidemiological Studies Depression (CES-D) scale (p < .001), which differed among race × gender subgroups. Further, amount of daily intake was inversely associated with self-report of depressive symptoms. For every 10-cigarette increment, the likelihood of scoring above the CES-D clinical cutoff decreased by 62% (p < .0001).

CONCLUSIONS

These findings improve our understanding of tobacco's influence on depressive symptom expression among heavy smokers, with implications for tailoring evidence-based tobacco treatments.

Dream-enacting behaviour is associated with impaired sleep and severe headache-related disability in migraine patients

BACKGROUND

Sleep disorders, nightmares and visual hallucinations have been reported in migraine patients, which may suggest the involvement of rapid eye movement (REM) sleep regulation in migraine. However, the relationship between migraine and REM sleep behaviour disorder (RBD) remains unclear.

METHODS

To investigate the clinical correlates of dream-enacting behaviours (DEB) in migraine patients, we assessed episodic migraine patients ( N  = 161, mean age 33.1 years) and headache-free control subjects ( N  = 140, mean age 33.1 years) under 50 years of age in a cross-sectional, case-control study. The Japanese version of the RBD screening questionnaire was used, and subjects scoring 5 or higher were defined as having DEB.

RESULTS

A significantly increased frequency of DEB was observed in migraine patients compared to controls (24.2% vs. 14.3%). Migraine patients with DEB presented higher scores on the Migraine Disability Assessment and Pittsburgh Sleep Quality Index and an increased rate of smoking compared to those without DEB. Duration of migraine and headache frequency and intensity were not different between migraine patients with or without DEB.

CONCLUSION

DEB was associated with impaired sleep and severe headache-related disability in migraine patients and may reflect brainstem dysfunction and increased brain excitability in migraine patients.

Sleep neurobiology from a clinical perspective

Many neurochemical systems interact to generate wakefulness and sleep. Wakefulness is promoted by neurons in the pons, midbrain, and posterior hypothalamus that produce acetylcholine, norepinephrine, dopamine, serotonin, histamine, and orexin/hypocretin. Most of these ascending arousal systems diffusely activate the cortex and other forebrain targets. NREM sleep is mainly driven by neurons in the preoptic area that inhibit the ascending arousal systems, while REM sleep is regulated primarily by neurons in the pons, with additional influence arising in the hypothalamus. Mutual inhibition between these wake- and sleep-regulating regions likely helps generate full wakefulness and sleep with rapid transitions between states. This up-to-date review of these systems should allow clinicians and researchers to better understand the effects of drugs, lesions, and neurologic disease on sleep and wakefulness.

Fluoxetine exerts age-dependent effects on behavior and amygdala neuroplasticity in the rat

The selective serotonin reuptake inhibitor (SSRI) Prozac® (fluoxetine) is the only registered antidepressant to treat depression in children and adolescents. Yet, while the safety of SSRIs has been well established in adults, serotonin exerts neurotrophic actions in the developing brain and thereby may have harmful effects in adolescents. Here we treated adolescent and adult rats chronically with fluoxetine (12 mg/kg) at postnatal day (PND) 25 to 46 and from PND 67 to 88, respectively, and tested the animals 7–14 days after the last injection when (nor)fluoxetine in blood plasma had been washed out, as determined by HPLC. Plasma (nor)fluoxetine levels were also measured 5 hrs after the last fluoxetine injection, and matched clinical levels. Adolescent rats displayed increased behavioral despair in the forced swim test, which was not seen in adult fluoxetine treated rats. In addition, beneficial effects of fluoxetine on wakefulness as measured by electroencephalography in adults was not seen in adolescent rats, and age-dependent effects on the acoustic startle response and prepulse inhibition were observed. On the other hand, adolescent rats showed resilience to the anorexic effects of fluoxetine. Exploratory behavior in the open field test was not affected by fluoxetine treatment, but anxiety levels in the elevated plus maze test were increased in both adolescent and adult fluoxetine treated rats. Finally, in the amygdala, but not the dorsal raphe nucleus and medial prefrontal cortex, the number of PSA-NCAM (marker for synaptic remodeling) immunoreactive neurons was increased in adolescent rats, and decreased in adult rats, as a consequence of chronic fluoxetine treatment. No fluoxetine-induced changes in 5-HT_1A receptor immunoreactivity were observed. In conclusion, we show that fluoxetine exerts both harmful and beneficial age-dependent effects on depressive behavior, body weight and wakefulness, which may relate, in part, to differential fluoxetine-induced neuroplasticity in the amygdala.