Acoustic startle and prepulse inhibition predict smoking lapse in posttraumatic stress disorder

Stressing out! Effects of acute stress on prepulse inhibition and working memory

Prepulse inhibition (PPI) of the startle reflex serves as a pre-cognitive marker of sensorimotor gating, and its deficit may predict cognitive impairments. Startle reflex is modulated by many factors. Among them, stress has been a topic of interest, but its effects on both pre-cognitive and cognitive variables continue to yield divergent results. This study aims to analyze the effect of acute stress on PPI of the startle reflex and cognitive function (working memory, attention, inhibition, and verbal fluency). Participants were exposed to the MAST stress induction protocol or a stress-neutral task: stress group (n = 54) or control group (n = 54). Following stress induction, participants' startle responses were recorded, and cognition was assessed. The results revealed that participants in the stress group exhibited greater startle magnitude, lower PPI, and lower scores in working memory tests compared with the control group. Additionally, a correlation was found between working memory and PPI across all the participants, independent of stress group. These findings support the notion that after stress, both greater startle magnitude and diminished PPI could play an adaptive role by allowing for increased processing of stimuli potentially dangerous and stress-related. Similarly, our results lend support to the hypothesis that lower PPI may be predictive of cognitive impairment. Considering the impact of stress on both pre-cognitive (PPI) and cognitive (working memory) variables, we discuss the possibility that the effect of stress on PPI occurs through motivational priming and emphasize the relevance of considering stress in both basic and translational science.

Tobacco use, trauma exposure and PTSD: a systematic review

Tobacco use remains one of the most significant preventable public health problems globally and is increasingly concentrated among vulnerable groups, including those with trauma exposure or diagnosed with PTSD. The goal of this systematic review was to update and extend previous reviews. Of the 7224 publications that met the initial criteria, 267 were included in the review. Summary topic areas include conceptual frameworks for the relation between trauma or PTSD and tobacco use; associations between trauma exposure or PTSD and tobacco use; number and type of trauma exposures and tobacco use; PTSD symptoms and tobacco use; Treatment-related studies; and the examination of causal relations. Evidence continues to indicate that individuals exposed to trauma or diagnosed with PTSD are more likely to use tobacco products, more nicotine dependent and less likely to abstain from tobacco even when provided evidence-based treatments than individuals without trauma. The most commonly cited causal association proposed was use of tobacco for self-regulation of negative affect associated with trauma. A small proportion of the studies addressed causality and mechanisms of action. Future work should incorporate methodological approaches and measures from which we can draw causal conclusions and mechanisms to support the development of viable therapeutic targets.

Tobacco withdrawal-induced changes in sensorimotor filtering as a predictor of smoking lapse in trauma-exposed individuals

Prepulse inhibition (PPI) is a measure of sensorimotor filtering thought to shield the processing of initial weaker auditory stimuli from interruption by a later startle response. Previous studies have shown smoking withdrawal to have a negative impact on sensorimotor filtering, particularly in individuals with psychopathology. Because tobacco use may alleviate sensory and sensorimotor filtering deficits, we examined whether smoking withdrawal-induced changes in PPI were associated with maintenance of smoking abstinence in trauma-exposed individuals with and without PTSD who were attempting to quit smoking. Thirty-eight individuals (n = 24 with current or past PTSD; 14 trauma-exposed healthy controls) made an acute biochemically-verified smoking cessation attempt supported by 8 days of contingency management (CM) and cognitive behavioral therapy (CBT) for smoking. Participants completed a PPI task at the pre-quit baseline, 2 days post-quit, and 5 days post-quit. Post-quit changes in PPI were compared between those who remained abstinent for the first 8-days of the quit attempt and those who lapsed back to smoking. PPI changes induced by biochemically-verified smoking abstinence were associated with maintenance of abstinence across the 8-day CM/CBT-supported quit attempt. As compared to those who maintained tobacco abstinence, participants who lapsed to smoking had significantly lower PPI at 2 and 5 days post-quit relative to baseline. Thus, among trauma-exposed individuals, decreases in PPI during acute smoking cessation supported by CM/CBT are associated with lapse back to smoking. Interventions that improve PPI during early smoking abstinence may facilitate smoking cessation among such individuals who are at high risk for chronic, refractory tobacco use.

Prepulse inhibition deficit as a transdiagnostic process in neuropsychiatric disorders: a systematic review

BACKGROUND

Psychopathological research is moving from a specific approach towards transdiagnosis through the analysis of processes that appear transversally to multiple pathologies. A phenomenon disrupted in several disorders is prepulse inhibition (PPI) of the startle response, in which startle to an intense sensory stimulus, or pulse, is reduced if a weak stimulus, or prepulse, is previously presented.

OBJECTIVE AND METHODS

The present systematic review analyzed the role of PPI deficit as a possible transdiagnostic process for four main groups of neuropsychiatric disorders: (1) trauma-, stress-, and anxiety-related disorders (2) mood-related disorders, (3) neurocognitive disorders, and (4) other disorders such as obsessive-compulsive, tic-related, and substance use disorders. We used Web of Science, PubMed and PsycInfo databases to search for experimental case-control articles that were analyzed both qualitatively and based on their potential risk of bias. A total of 64 studies were included in this systematic review. Protocol was submitted prospectively to PROSPERO 04/30/2022 (CRD42022322031).

RESULTS AND CONCLUSION

The results showed a general PPI deficit in the diagnostic groups mentioned, with associated deficits in the dopaminergic neurotransmission system, several areas implied such as the medial prefrontal cortex or the amygdala, and related variables such as cognitive deficits and anxiety symptoms. It can be concluded that the PPI deficit appears across most of the neuropsychiatric disorders examined, and it could be considered as a relevant measure in translational research for the early detection of such disorders.

Identification of slit3 as a locus affecting nicotine preference in zebrafish and human smoking behaviour

To facilitate smoking genetics research we determined whether a screen of mutagenized zebrafish for nicotine preference could predict loci affecting smoking behaviour. From 30 screened F3 sibling groups, where each was derived from an individual ethyl-nitrosurea mutagenized F0 fish, two showed increased or decreased nicotine preference. Out of 25 inactivating mutations carried by the F3 fish, one in the slit3 gene segregated with increased nicotine preference in heterozygous individuals. Focussed SNP analysis of the human SLIT3 locus in cohorts from UK (n=863) and Finland (n=1715) identified two variants associated with cigarette consumption and likelihood of cessation. Characterisation of slit3 mutant larvae and adult fish revealed decreased sensitivity to the dopaminergic and serotonergic antagonist amisulpride, known to affect startle reflex that is correlated with addiction in humans, and increased htr1aa mRNA expression in mutant larvae. No effect on neuronal pathfinding was detected. These findings reveal a role for SLIT3 in development of pathways affecting responses to nicotine in zebrafish and smoking in humans.

Posttraumatic stress disorder and tobacco use: A systematic review and meta-analysis

Posttraumatic stress disorder (PTSD) and tobacco use are prevalent conditions that co-occur at striking rates in the US. Previous reviews examined prevalence and factors associated with cigarette smoking among individuals with PTSD but have not been summarized since 2007. Moreover, none explored rates and factors associated with the use of other tobacco products. This study aimed to systematically review the most recent literature examining the comorbidity of PTSD and tobacco use to provide prevalence rates, as well as summarize the literature exploring other factors associated with tobacco use among individuals with PTSD. Studies were identified using a systematic search of keywords related to tobacco use and PTSD within the following databases: PubMed, PsycINFO, Web of Knowledge, CINAHL, PsycARTICLES, and Cochrane Clinical Trials Library. The studies included in this review (N = 66) showed that the prevalence of current use of tobacco products in individuals with PTSD was 24.0% and the rate of PTSD among users of tobacco products was 20.2%. Additionally, results demonstrated that individuals with PTSD present with high levels of nicotine dependence and heavy use of tobacco products, as well as underscore the importance of negative emotional states as a contributing factor to tobacco use among individuals with PTSD. It is imperative that future studies continue monitoring tobacco use among individuals with PTSD while also assessing factors identified as having a prominent role in tobacco use among individuals with PTSD. These findings also demonstrate the need for more innovative approaches to reduce the pervasive tobacco use among individuals with PTSD.