Nevertheless, the demonstrations of cognitive recovery in abstinent PSU, and potential effects of smoking status on such recovery, are consistent with our observations of corresponding recovery in abstinent AUD . The 19 PSU not studied at follow-up differed significantly from abstinent PSU at baseline on several important variables: they had more years of cocaine use over lifetime, and performed worse on cognitive efficiency, processing speed, and visuospatial learning. As such, these differences should be tested as potential predictors of relapse in future larger studies. Several factors limit the generalizability of our findings. Our cross-sectional sample size was modest and therefore our longitudinal sample of abstinent PSU was small; as not uncommon in clinical samples, about half of our PSU cohort relapsed between baseline and follow-up, a rate comparable to what has been reported elsewhere . This made us focus our longitudinal results reporting on the main effects of time and to de-emphasize the reporting of time-by-smoking status interactions. Larger studies are needed to examine the potential effects of smoking status and gender on neurocognitive recovery during abstinence from substances. The study sample was drawn from treatment centers of the Veterans Affairs system in the San Francisco Bay Area and a communitybased healthcare provider, and the ethnic breakdown of the study groups was different . Therefore, our sample may not be entirely representative of community-based substance use populations in general. Although preliminary, the within subject statistics are meaningful as they are more informative for assessing change over time than larger cross-sectional studies at various durations of abstinence. In addition, premorbid biological factors and other behavioral factors not assessed in this study may have influenced cross-sectional and longitudinal outcome measures. Nonetheless,flood tray our study is important and of clinical relevance in that it describes deficits in neurocognition and inhibitory control of detoxified PSU that are different from those in AUD, and that appear to recover during abstinence from substances, potentially as a function of smoking status.
Our cross-sectional and longitudinal findings are valuable for improving current substance use rehabilitation programs. The higher impulsivity and reduced cognitive abilities of PSU compared to AUD, likely the result of long-term comorbid substance use, and the lack of improvements in learning and memory during abstinence indicate a potentially reduced ability of PSU to acquire new cognitive skills necessary for remediating maladaptive behavioral patterns that impede successful recovery. As such, PSU may require a post-detox treatment approach that accounts for these specific deficits relative to AUD. Our results show that PSU able to maintain abstinence for 4 months had less total lifetime years of cocaine use and performed better on cognitive efficiency, processing speed and visuospatial learning than those PSU not restudied ; these variables may therefore be valuable for predicting future abstinence or relapse in PSU. Additionally, and if confirmed in larger studies, our preliminary results on differential neurocognitive change in smoking and nonsmoking PSU may inform a treatment design that addresses the specific needs of these subgroups within this largely understudied population of substance users. Potentially, concurrent treatment of cigarette smoking in treatment-seeking PSU may also help improve long-term substance use outcomes, just as recently proposed for treatment seeking individuals with AUD . Finally, our findings on neurocognitive improvement in PSU imply that cognitive deficits are to some extent a consequence of long-term substance use , which have the potential for remediation with abstinence. This information is of clinical relevance and of psychoeducational value for treatment providers and treatment-seeking PSU alike. Rates of adult marijuana use have grown substantially in the US over the past decade, particularly among those aged 26 years or older and those that are daily cigarette smokers . This is of concern, as evidence indicates that marijuana use can lead to addiction and use of other substances, motor vehicle accidents, impaired brain development, psychiatric conditions, and respiratory problems . Concurrent use of tobacco and marijuana is common, although not uniform across tobacco products .
Estimates indicate that between 25% and 52% of tobacco smokers use cannabis and, among past month marijuana users, 68% also reported tobacco use . Further, concurrent use of marijuana and tobacco increased from 2003 to 2012 . Use of marijuana and cigarettes or cigars is commonly reported among tobacco users , though less is known about the relationship between marijuana use and multiple tobacco products. About 40% of current tobacco users in the US report use of multiple products, and cigarettes + e-cigarettes are the most common combination . Among multiple product users, there are also differences in types of products used and prevalence of use by age, gender, and race/ethnic group .The opportunities for co-administration provided by modification of tobacco products may represent one source of interest in tobacco products among marijuana concurrent users . For example, electronic devices engineered to aerosolize tobacco, marijuana, and other substances may be marketed to promote cooccurring use . Tobacco products that can be readily modified for marijuana use may not only increase tobacco use among marijuana users, but also expand the types of tobacco products used by an individual. Frequent use of marijuana has been linked with persistent tobacco use and greater tobacco dependence among youth and adults and higher expectancies that each substance promotes the use of the other . Among concurrent users, motivation to reduce marijuana and the relative perception of harm from use of marijuana have been lower than for tobacco. Concurrent use of marijuana and tobacco products may promote persistent tobacco use and decreased motivation to alter use of marijuana , reduce users’ interest in quitting tobacco , and reduce success in cessation . By impairing cessation efforts, concurrent use may serve to exacerbate the negative consequences from both tobacco and marijuana.
The health effects of persistent tobacco use and use of marijuana show clear associations with acute and chronic respiratory symptoms . When combusted, both inhaled tobacco and marijuana smoke deposit tar and other constituents in the lung . Cellular abnormalities associated with respiratory disorders including bronchitis and chronic obstructive pulmonary disease have been observed in both tobacco and marijuana users . A US population examination of respiratory symptoms among marijuana smokers suggested higher rates of bronchitis, coughing, phlegm production, and wheezing after statistically adjusting for cigarette smoking . The effects of marijuana use on respiratory health among other and multiple tobacco product user groups, including users of aerosolized products in the US population, have not been examined. The rapidly changing landscape of tobacco and marijuana products and consumption devices, particularly in the context of marijuana legalization and increasing use, indicate the importance of characterizing patterns of tobacco and marijuana use. Our primary aim is to describe the relationship between current marijuana use and pattern of current tobacco product use using a comprehensive assessment of tobacco products. We hypothesized that users of tobacco would have higher rates of current marijuana use than those not currently using tobacco products and that effects would be strongest for current users of tobacco products with inhaled routes of administration that accommodate co-administration relative to current non-inhaled tobacco product users. We also hypothesized that among current tobacco users, concurrent use of any tobacco product and marijuana would be associated with increased tobacco dependence and a decreased motivation to quit tobacco use. Finally,grow table we hypothesized that concurrent users of inhaled tobacco products and marijuana would have higher rates of respiratory conditions relative to those not currently using tobacco products.We used logistic regression to estimate the relationship between current marijuana use among users and non-users of tobacco products, with non-tobacco-users as the reference group . Planned covariates for all models included age, gender, and racial/ ethnic group. With a focus on current tobacco users, Hypothesis 2 evaluated reports of marijuana use for each user group using cigarette only users as the reference . We then added a term reflecting levels of tobacco dependence and re-evaluated the independent association between tobacco use group and current marijuana use . Logistic regression models were also used to explore relationships between current marijuana use, past quit attempts, and current intentions to quit among current users of tobacco products. Lastly, for Hypothesis 3, logistic regression models were used to estimate the odds of a respiratory condition for current tobacco users relative to those not currently using tobacco.
A dummy coded term for current marijuana use was used in interaction terms to assess potential moderating effects of marijuana use on relationships between tobacco product use and respiratory conditions.Among current tobacco users, we first estimated any increase in odds of marijuana use of each user group in reference to cigarette only users . E-cigarette only, hookah only, and cigarette + e-cigarette users did not differ significantly from cigarette only users in the odds of reporting current marijuana use. Cigar only and multiple product users had significantly greater odds of reporting current marijuana use than cigarette only users. Smokeless only users had significantly reduced odds of marijuana use compared to cigarette only users. We examined the hypothesis that tobacco dependence may account for significant differences in current marijuana use across tobacco user groups by adding the TD scale to the demographically adjusted model . This hypothesis was not supported, as each significant association noted in Model B remained significant in Model C, and each effect size remained largely unchanged. Follow-up exploratory analysis did not suggest any moderated relationship between tobacco user groups and TD scores, as the set of interaction terms when added after all other lower-order terms was not significant = 0.53, p = 0.78).The present study examined the differential prevalence of co-use of marijuana among distinct types of tobacco product user groups, impacts on tobacco dependence, efforts to stop tobacco, and current respiratory problems. Cigar only and multiple product users consistently had the highest rates of marijuana use. These product-specific patterns were maintained after adjusting for differences in demographics and after accounting for the strong relationship between tobacco dependence and current marijuana use. Tobacco product characteristics that may afford opportunity for delivery of marijuana may increase their appeal to concurrent users of marijuana. Alternatively, concurrent use may serve to promote expanded use of tobacco products . Rates of concurrent use decreased steadily across age groups for all tobacco product users except smokeless only users, whose rates remained similar to non-users across age groups. While we adjust statistically for the influence of age on the relationship between product use and increased current marijuana use, the increase in concurrent use of these products among youth, where cigar and multiple product use is most common, is of particular concern. However, the extent to which the currently observed greater rates of concurrent use among youth differ from historical patterns is unknown. Differences in product user groups also reflect, in part, differences in tobacco dependence . Associations between concurrent use and dependence are well documented and have plausible mechanisms via enhanced reinforcement, conditioned pairings to strengthen cues for concurrent use, and amelioration of cognitive deficits of marijuana use alone . When examining the relative impact of levels of dependence, no observed relationship between product user group and concurrent use of marijuana was affected. This suggests an additive effect of dependence rather than a sole common causal relationship. Previous studies have suggested that marijuana use is associated with persistent tobacco use and decreased efforts to quit tobacco . Present findings indicate that although concurrent marijuana use did not correspond with reduced intentions to quit tobacco, it was associated with lower likelihood of reporting a past year quit attempt among some user groups. Concurrent users may be more dependent on marijuana , may have an increased difficulty with marijuana cessation when they continue to use tobacco , may have more psychosocial impairments , and may be less motivated to reduce tobacco use . Current marijuana use may be a barrier to tobacco cessation, not because it interferes directly with intentions to quit, but because it is associated with reduced chances that a concurrent user will be attempting to quit.Additive effects of concurrent use of marijuana and tobacco on respiratory symptoms heighten public health concerns over potential exacerbation of health effects of marijuana on lung disorders and increased odds of respiratory conditions among both users and non-users of tobacco products .