Family income trajectory during childhood is associated with adolescent cigarette smoking and alcohol use

Background

Although childhood socioeconomic disadvantage has been linked with adolescent tobacco and alcohol use in cross-sectional research, less is known about the influence of changes in socioeconomic status during childhood. Upward socioeconomic mobility may attenuate the negative influence of earlier socioeconomic disadvantage on health, while downward mobility may counter the health benefits of earlier socioeconomic advantage. This study evaluated the influence of common trajectories of family income during childhood on smoking and alcohol use during adolescence.

Methods

Data utilized were part of the 15-year longitudinal Study of Early Child Care and Youth Development. A 5-class trajectory model (two stable, one downward, and two upward income trajectories) was developed previously with this sample (N = 1356). Logistic regression analyses were conducted to determine whether children of the more disadvantaged income trajectories were more likely to engage in tobacco and alcohol use at age 15 relative to those of the most advantaged trajectory.

Results

Family income trajectory was significantly associated with ever-smoking (p = .02) and past-year alcohol use at age 15 years (p = .008). Children from the less advantaged trajectories were more likely to have ever-smoked than children of the most advantaged trajectory (all p's < .05). Children of the downwardly mobile trajectory were more likely to have used alcohol within the past year than children of the most advantaged trajectories as well as the most disadvantaged trajectory (all p's < .05).

Conclusions

Findings indicate that childhood socioeconomic disadvantage influences adolescent smoking, while downward socioeconomic mobility influences adolescent alcohol use.     

Moderate/heavy alcohol use and HCV infection among injection drug users in two Russian cities

Background

In Russia, injection drug use and transmission of blood-borne pathogens such as human immunodeficiency virus (HIV) and hepatitis C virus (HCV) are inextricably linked, however the burden of alcohol use remains unexplored among injection drug users (IDUs).

Methods

Individuals who were 18 years of age and older and had injected drugs in the previous 30 days were recruited in the cities of Novosibirsk and Ivanovo by respondent driven sampling. Consenting individuals were administered a quantitative survey instrument and provided blood samples for serological testing.

Results

In Novosibirsk and Ivanovo, 29% and 35% of respondents were categorized as moderate/heavy drinkers, respectively. Individuals reported problems related to alcohol use that affected their physical health (23%), family (55%), and induced financial hardships (43%). In the multivariate analysis, we found that methamphetamine injection in the past 12 months was a strong and significant correlate of moderate/heavy drinking in Novosibirsk (aOR = 5.63 95% CI: [1.01–31.47]) and Ivanovo (aOR = 3.81 95% CI: [2.20–6.62]). There was poor agreement between self-reported HCV status and HCV test results (κ = −0.05 and 0.26 in Novosibirsk and Ivanovo, respectively). IDUs who correctly knew their HCV seropositive status in Novosibirsk and IDUs who correctly knew their HCV seronegative status in Ivanovo were significantly more likely to be moderate/heavy drinkers.

Conclusion

Alcohol use is problematic among IDUs who are at high risk for HCV. Future interventions should target IDUs who are moderate/heavy drinkers in order to prevent liver complications resulting from HCV infection.     

Past and current alcohol consumption patterns and elevations in serum hepatic enzymes among US adults

Objective

The aim of this study was to examine the association between patterns of past and current alcohol consumption and elevations in serum hepatic enzymes among a nationally representative sample of adults in the United States.

Methods

We estimated the age-adjusted prevalence of elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) among 8993 adults aged 20 years or older who participated in the 2005-2008 National Health and Nutrition Examination Survey (NHANES). We produced prevalence ratios by using patterns of alcohol consumption as a predictor; elevations in serum ALT, AST, and GGT were used as an outcome variable while adjusting for covariates in multivariate regression models.

Results

The age-adjusted prevalence of elevated serum ALT, AST, and GGT in adults was 9.7%, 16.0%, and 8.6%, respectively. Male excessive current drinkers had 50%-71% and 75%-314% increased likelihoods of having elevated serum AST and GGT, respectively; female excessive drinkers with a history of consuming 5 or more drinks almost daily had a 226% increased likelihood of having elevated serum GGT, when compared to their respective counterparts who were lifetime abstainers.

Conclusions

The results of this study indicate that elevations in serum hepatic enzymes, especially AST and GGT, are common in adults who are excessive current drinkers. There is evidence to suggest that excessive current drinkers with a history of protracted drinking are especially vulnerable to potential liver injury. These findings lend further support to the early identification of excessive drinkers who may have an increased risk for alcohol-related morbidity and mortality in health care settings.     

Effect of motivational interviewing on reduction of alcohol use

Background

Methadone-maintained (MM) clients who engage in excessive alcohol use are at high risk for HIV and hepatitis B virus (HBV) infection. Nurse-led hepatitis health promotion (HHP) may be one strategy to decrease alcohol use in this population.

Objective

To evaluate the impact of nurse-led HHP, delivered by nurses compared to motivational interviewing (MI), delivered by trained therapists in group sessions or one-on-one on reduction of alcohol use.

Methods

A three-arm randomized, controlled trial, conducted with 256 MM adults attending one of five MM outpatient clinics in the Los Angeles area. Within each site, moderate-to-heavy alcohol-using MM participants were randomized into one of three conditions: (1) nurse-led hepatitis health promotion group sessions (n = 87); (2) MI delivered in group sessions (MI-group; n = 79), or (3) MI delivered one-on-one sessions (MI-single, n = 90).

Results

Self-reported alcohol use was reduced from a median of 90 drinks/month at baseline to 60 drinks/month at 6-month follow-up. A Wilcoxon sign-rank test indicated a significant reduction in alcohol use in the total sample (p < .05). In multiple logistic regression analysis controlling for alcohol consumption at baseline and other covariates, no differences by condition were found.

Discussion

As compared to two programs delivered by MI specialists, a culturally-sensitive and easy to implement nurse-led HHP program produced similar reductions in alcohol use over 6 months. Employing nurse-led programs may allow cost savings for treatment programs as well as a greater integration of alcohol reduction counseling along with a more comprehensive focus on general health-related issues than previously conducted.     

Internal mouthpiece designs as a future perspective for enhanced aerosol deposition. Comparative results for aerosol chemotherapy and aerosol antibiotics

Background

In an effort to identify factors producing a finest mist from Jet-Nebulizers we designed 2 mouthpieces with 4 different internal designs and 1–3 compartments.

Materials and methods

Ten different drugs previous used with their “ideal” combination of jet-nebulizer, residual-cup and loading were used. For each drug the mass median aerodynamic diameter size had been established along with their “ideal” combination.

Results

For both mouthpiece, drug was the most important factor due the high F-values (F_large = 251.7, p < 0.001 and F_small = 60.1, p < 0.001) produced. The design affected the droplet size but only for large mouthpiece (F_large = 5.99, p = 0.001, F_small = 1.72, p = 0.178). Cross designs create the smallest droplets (2.271) so differing from the other designs whose mean droplets were greater and equal ranging between 2.39 and 2.447. The number of compartments in the two devices regarding the 10 drugs was found not statistically significant (p-values 0.768 and 0.532 respectively). Interaction effects between drugs and design were statistically significant for both devices (F_large = 8.87, p < 0.001, F_small = 5.33, p < 0.001).

Conclusion

Based on our experiment we conclude that further improvement of the drugs intended for aerosol production is needed. In addition, the mouthpiece design and size play an important role in further enhancing the fine mist production and therefore further experimentation is needed.     

Social desirability biases in self-reported alcohol consumption and harms

Aims

Self-reports remain the most common means of assessing alcohol consumption despite concern for their validity. The objective of this research is to assess the extent to which social desirability biases relate to self-reported consumption, hazardous use, and harms.

Methods

In each of two studies presented, undergraduate students (N = 391 and N = 177) who reported that they had consumed alcohol in the past year completed online confidential surveys.

Results

Both studies show consistent associations between impression management bias and self-reported consumption such that high impression managers report 20 to 33% less consumption and are about 50% less likely to report risky drinking. No significant correlations involving consumption were found for self-deception bias. Study 2 also indicated that high impression managers report 30–50% fewer acute harms following a drinking episode, and that these effects are maintained after controlling statistically for trait impulsivity/constraint.

Conclusions

Impression management bias represents a significant threat to the validity of self-reported alcohol use and harms. Such bias may lead to misspecification of models and under-estimates of harmful or hazardous use.     

Self-perceived problem with alcohol use among opioid substitution treatment clients

Background and aim

Excessive alcohol use increases mortality and morbidity among opioid substitution therapy (OST) clients. Regular attendance for OST dosing presents key opportunities for screening and treatment. However, individuals' perception of their alcohol consumption as problematic or otherwise may impact their willingness to change. This study examines patterns of alcohol consumption among OST clients, perceptions of their own use and correlates of excess consumption.

Methods

Confidential, structured interviews were conducted with 264 clients of two Sydney OST clinics. Alcohol consumption was assessed using the Alcohol Use Disorders Identification Test (AUDIT); and illicit drug dependence with the Severity of Dependence Scale.

Results

Forty-one percent of the participants scored ≥ 8 on the AUDIT (‘AUDIT-positive’), indicating excessive alcohol use. The higher a participant's AUDIT score, the more likely they were to demonstrate insight into the potential problems associated with their drinking (linear trend, p < 0.01). However, only half of AUDIT-positive participants believed they drank too much and/or had a problem with alcohol. One-third had discussed their drinking with OST staff, and a similar proportion reported a history of alcohol treatment. AUDIT-positive participants were more likely than others to be classified as dependent on an illicit drug in the last six months (AOR = 1.76, 95% CI:1.00–3.09), report a history of alcohol treatment (AOR = 5.70, 95% CI:2.83–11.48) and believe it is safe to drink 4 + standard drinks in one session (AOR = 5.30, 95% CI:2.79–10.06).

Conclusions

OST clients with AUDIT scores ≥ 8 appear to underestimate the risks associated with their alcohol consumption. Regular assessments of alcohol use and targeted brief alcohol interventions may improve health outcomes among OST clients.     

An evaluation of hepatic enzyme elevations among HIV-infected released prisoners enrolled in two randomized placebo-controlled trials of extended release naltrexone

Extended-release naltrexone (XR-NTX), an approved treatment for opioid or alcohol dependence, is a once-monthly injectable formulation of naltrexone. Hepatotoxicity concerns have limited its use, necessitating further investigation. This study aims to examine hepatic enzyme levels in participants of 2 randomized placebo-controlled trials (RCTs) of XR-NTX. Hepatic transaminases were measured in 85 patients enrolled in RCTs of XR-NTX among HIV-infected prisoners, transitioning to the community and receiving treatment for either dependence on alcohol (52.9%), opioids (44.7%) or both (16.5%). Baseline characteristics included HCV co-infection (55.7%), antiretroviral therapy (81%), mental illness (39%) and receiving psychiatric medications (34.1%). Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) were not statistically different between persons randomized to placebo (N = 24) and XR-NTX (N = 61) arms. These results confirm that XR-NTX is safe to use among opioid and alcohol dependent HIV-infected released prisoners receiving ART with high rates of co-morbid HCV infection and mental illness.     

Brief motivational enhancement intervention to prevent or reduce postpartum alcohol use: A single-blinded,randomized controlled effectiveness trial

Aims

The aim of this study is to assess the effect of brief motivational enhancement intervention postpartum alcohol use.

Design

This study is a single-blinded, randomized controlled effectiveness trial in which pregnant women were assigned to receive usual care or up to 5 face-to-face brief motivational enhancement sessions lasting 10–30 minutes each and occurring at study enrollment, 4 and 8 weeks after enrollment, 32 weeks of gestation, and 6 weeks postpartum.

Setting

The setting is in a large, urban, obstetrics clinic.

Participants

Participants were women who were ≥ 18 years old, < 20 weeks of gestation, and consumed alcohol during pregnancy. Of 3438 women screened, 330 eligible women were assigned to usual care (n = 165) or intervention (n = 165). Due to missing data, we analyzed 125 in the intervention group and 126 in the usual care group.

Measurements

The measurements were the proportion of women with any alcohol use and the number of drinks per day, reported via follow-up telephone interviews at 4 and 8 weeks after enrollment, 32 weeks of gestation, and 6 weeks, 6 months, and 12 months postpartum.

Findings

In random effects models adjusted for confounders, the intervention group was less likely to use any alcohol (odds ratio 0.50; 95% confidence interval [CI], 0.23–1.09; P = 0.08) and consumed fewer drinks per day (coefficient − 0.11; 95% CI − 0.23–0.01; P = 0.07) than, the usual care group in the postpartum period but these differences were non-significant. Missing data during the prenatal period prevented us from modeling prenatal alcohol use.

Conclusions

Brief motivational enhancement intervention delivered in an obstetrical outpatient setting did not conclusively decrease alcohol use during the postpartum period.     

Maternal alcohol consumption producing fetal alcohol spectrum disorders (FASD): Quantity,frequency, and timing of drinking

Background

Concise, accurate measures of maternal prenatal alcohol use are needed to better understand fetal alcohol spectrum disorders (FASD).

Methods

Measures of drinking by mothers of children with specific FASD diagnoses and mothers of randomly-selected controls are compared and also correlated with physical and cognitive/behavioral outcomes.

Results

Measures of maternal alcohol use can differentiate maternal drinking associated with FASD from that of controls and some from mothers of alcohol-exposed normals. Six variables that combine quantity and frequency concepts distinguish mothers of FASD children from normal controls. Alcohol use variables, when applied to each trimester and three months prior to pregnancy, provide insight on critical timing of exposure as well. Measures of drinking, especially bingeing, correlate significantly with increased child dysmorphology and negative cognitive/behavioral outcomes in children, especially low non-verbal IQ, poor attention, and behavioral problems. Logistic regression links (p < .001) first trimester drinking (vs. no drinking) with FASD, elevating FASD likelihood 12 times; first and second trimester drinking increases FASD outcomes 61 times; and drinking in all trimesters 65 times. Conversely, a similar regression (p = .008) indicates that drinking only in the first trimester makes the birth of a child with an FASD 5 times less likely than drinking in all trimesters.

Conclusions

There is significant variation in alcohol consumption both within and between diagnostic groupings of mothers bearing children diagnosed within the FASD continuum. Drinking measures are empirically identified and correlated with specific child outcomes. Alcohol use, especially heavy use, should be avoided throughout pregnancy.     

Alcohol dependent inpatients who receive general hospital care vs. detoxification in psychiatric care and alcohol problem 1 year later

Aim

The aims were to investigate differences between alcohol dependent inpatients who seek alcohol treatment and those who do not seek alcohol specific but general hospital treatment, and to investigate problem drinking 12 months after hospitalization.

Methods

Two samples of alcohol dependent inpatients were recruited: N = 571 at general hospitals and N = 473 at psychiatric alcohol detoxification units, and were followed-up 12 months later.

Results

Multivariate logistic regression analyses revealed that higher age, living alone, being employed, previous help-seeking, increased severity of dependence, increased adverse consequences from drinking and increased motivation were significant predictors of receiving alcohol detoxification vs. general hospital treatment. A composite assessment of motivation to change and to seek help was the strongest predictor of positive outcome 12 months later.

Conclusions

Alcohol dependent individuals who receive detoxification in psychiatric care have a more severe alcohol problem and fewer social resources than those treated in general hospitals. Interventions targeting at enhancing motivation to change and to seek help should be part of routine general hospital care and of detoxification treatment in psychiatric care.     

Alcohol and drug use and related consequences among gay,lesbian and bisexual college students: Role of experiencing violence,feeling safe on campus,and perceived stress

Objective

To examine differences between gay, lesbian, and bisexual (GLB) and non-GLB university students in alcohol and other drug use (AOD) and related consequences as well as the relevance of violence, perceived safety, and stress to any such differences in AOD use and related concerns.

Methods

A random representative sample of university students (n = 988) were recruited via email for an online survey. Linear regression models assessed associations between identifying as GLB and AOD use and related consequences.

Results

Regression models (adjusted for gender) indicated that, in comparison to heterosexual students, GLB students were more likely to report recent illicit drug use (AOR = 2.0; 95% CI: 1.1–3.9), more frequent negative AOD consequences (β = 5.5, SE = 1.4, p < 0.0001), and having seriously thought about/attempted suicide due to AOD use in the past year (AOR = 6.6; 95% CI: 3.0–14.3). Study findings also suggested that violence, safety, and stress variables partially contribute to AOD use and related concerns among GLB students.

Conclusions

Findings highlight the need for future efforts to investigate and address mechanisms, including aspects of campus life, which contribute to AOD related risks among GLB students.     

Public injecting and HIV risk behaviour among street-involved youth

Background

Although street-involved youth who inject illicit drugs are known to be at an increased risk of HIV and other adverse health outcomes, little is known about public injecting among this population and how injecting in public environments may impact HIV risk behaviour.

Methods

We used data derived from a study of 560 street-involved youth in Vancouver, Canada to examine the factors associated with injecting in public environments among youth who reported injecting drugs in the past 6 months.

Results

At baseline, 162 (28.9%) reported injecting drugs in the past 6 months. Among injectors, the 124 (76.5%) participants who reported injecting in public were more likely to be homeless (odds ratio [OR] = 6.39, p < 0.001), engage in unprotected intercourse (OR = 3.09, p = 0.004), deal drugs (OR = 2.26, p = 0.032), smoke crack cocaine (OR = 3.00, p = 0.005), inject heroin (OR = 3.48, p = 0.001), drop used syringes outdoors (OR = 8.44, p < 0.001), share syringes (OR = 4.43, p = 0.004), and were less likely to clean injection sites >75% of the time (OR = 0.36, p = 0.008). The majority (62.1%) reported feeling rushed while injecting in public.

Conclusions

Youth who inject in public are significantly more likely to engage in sexual and injection-related risk behaviour. Given the known elevated rates of HIV infection and other harms among this population, youth-focused interventions that target both sexual and drug-related risks associated with public drug-using environments are in urgent need of evaluation.     

Biological markers of problem drinking in homeless patients

Objective

In the search for optimal biomarkers of excessive drinking, a central limitation has been the lack of sensitivity of measures. Many patients have apparently normal values of liver markers despite a considerable alcohol intake. This study aimed to test a novel combined indicator of alcohol drinking.

Material and methods

Concentrations of carbohydrate-deficient transferrin (%CDT), γ glutamyl transferase (γGT), aspartate aminotransferase (ASAT), and mean corpuscular volume (MCV), together with a combined index of the %CDT and γGT, the Antilla Index (AI), were studied in 104 homeless patients with (n = 87) or without (n = 24) problem drinking according to the Fast Alcohol Screening Test.

Results

Concentrations of all markers were significantly higher in the alcoholic patients than in other homeless patients. The best agreement between liver markers and self-reported status was found between the combined %CDT and γGT index (kappa = 0.61, p < 0.001, sensitivity = 63%, specificity = 94%).

Conclusions

The combined AI is a relatively efficient measure of current drinking in homeless populations.     

Risky cognitions associated with adolescent alcohol misuse: Moral disengagement,alcohol expectancies and perceived self-regulatory efficacy

Aim

To examine the longitudinal associations between moral disengagement, alcohol related expectancies, perceived self-regulatory efficacy and alcohol use amongst adolescents.

Design and participants

A total of 367 students (mean age = 13.1, SD = 0.51; 65% male) from five schools across Sydney, Australia took part in this longitudinal study. Participants completed a self-report questionnaire at four time points across an 18 month period which assessed their alcohol use, levels of moral disengagement, alcohol related expectancies and perceived self-regulatory efficacy to resist peer pressure to engage in transgressive behaviours.

Results

Over time, rates of binge drinking in the past three months significantly increased, but rates of drinking any alcohol in the past three months remained stable. As hypothesised, all three cognitions were independently and consistently associated with adolescent alcohol use and binge drinking over time, with the exception of perceived self-regulatory efficacy which was not associated with an increased risk of drinking any alcohol in the past three months when controlling for moral disengagement, alcohol expectancies, gender and age.

Conclusions

The current study is the first study to longitudinally map three distinct cognitive factors associated with adolescent alcohol use. Considering the alarming number of adolescents drinking at levels that place them at risk of significant harm, this study has provided important implications about cognitive factors that can be targeted to increase the accuracy of assessment and efficacy of prevention for alcohol misuse amongst adolescents.     

Differences between abstinent and non-abstinent individuals in recovery from alcohol use disorders

Objective

Non-abstinent goals can improve quality of life (QOL) among individuals with alcohol use disorders (AUDs). However, prior studies have defined “recovery” based on DSM criteria, and thus may have excluded individuals using non-abstinent techniques that do not involve reduced drinking. Furthermore, no prior study has considered length of time in recovery when comparing QOL between abstinent and non-abstinent individuals. The current aims are to identify correlates of non-abstinent recovery and examine differences in QOL between abstainers and non-abstainers accounting for length of time in recovery.

Sample

A large (N = 5380) national sample of individuals who self-describe as “in recovery” from alcohol problems recruited in the context of the What Is Recovery? (WIR) study.

Method

Multivariate stepwise regressions estimating the probability of non-abstinent recovery and average quality of life.

Results

Younger age (OR = 0.72), no prior treatment (OR = 0.63) or AA (OR = 0.32), fewer dependence symptoms (OR = 0.17) and less time in recovery all significantly (P < 0.05) related to non-abstinent recovery. Abstainers reported significantly (P < 0.05) higher QOL than non-abstainers (B = 0.39 for abstinence vs. non-abstinence), and abstinence was one of the strongest correlates of QOL, even beyond sociodemographic variables like education.

Conclusions

Non-abstainers are younger with less time in recovery and less problem severity but worse QOL than abstainers. Clinically, individuals considering non-abstinent goals should be aware that abstinence may be best for optimal QOL in the long run. Furthermore, time in recovery should be accounted for when examining correlates of recovery.     

Project Reduce: Reducing alcohol and marijuana misuse: Effects of a brief intervention in the emergency department

Study objective

Brief interventions (BI) for alcohol misuse and recently for marijuana use for emergency department patients have demonstrated effectiveness. We report a 12-month outcome data of a randomized controlled trial of emergency department (ED) patients using a novel model of BI that addresses both alcohol and marijuana use.

Methods

ED research assistants recruited adult patients who admitted alcohol use in the last month, and marijuana use in the last year. In the ED, patients received an assessment of alcohol and marijuana use and were randomized to treatment (n = 249) or standard care (n = 266). Treatment consisted of two sessions of BI. At 3 and 12 months, both groups had an assessment of alcohol and marijuana use and negative consequences of use.

Results

515 patients were randomized. We completed a 12-month follow-up assessments on 83% of those randomized. Measures of binge drinking and conjoint marijuana and alcohol use significantly decreased for the treatment group compared to the standard care group. At 12-month binge alcohol use days per month in the treatment group were (M = 0.72:95% CI = 0.36–1.12) compared to standard care group (M = 1.77:95% CI = 1.19–1.57) Conjoint use days in the treatment group (M = 1.25.1:95% CI = 0.81–1.54) compared to standard care group (M = 2.16:95% CI = 1.56–2.86). No differences in negative consequences or injuries were seen between the treatment and standard care groups.

Conclusions

BI for alcohol and marijuana decreased binge drinking and conjoint use in our treatment group. BI appears to offer a mechanism to reduce risky alcohol and marijuana use among ED patients but expected reductions in consequences of use such as injury were not found 12 months after the ED visit.     

γ-Amino butyric acid and glutamate abnormalities in adolescent chronic marijuana smokers

Background

An increasing body of evidence from neuropsychological and neuroimaging studies suggests that exposure to marijuana throughout adolescence disrupts key cortical maturation processes occurring during this developmental phase. GABA-modulating pharmacologic treatments that elevate brain GABA concentration recently have been shown to decrease withdrawal symptoms and improve executive functioning in marijuana-dependent adult subjects. The goal of this study was to investigate whether the lower ACC glutamate previously reported in adolescent chronic marijuana smokers is associated with lower ACC GABA levels.

Methods

Standard and metabolite-edited proton MRS data were acquired from adolescent marijuana users (N = 13) and similarly aged non-using controls (N = 16) using a clinical 3T MRI system.

Results

The adolescent marijuana-using cohort showed significantly lower ACC GABA levels (−22%, p = 0.03), which paralleled significantly lower ACC glutamate levels (−14%, p = 0.01). Importantly, the lower ACC GABA and glutamate levels detected in the adolescent cohort remained significant after controlling for age and sex.

Conclusions

The present spectroscopic findings support functional neuroimaging data documenting cingulate dysfunction in marijuana-dependent adolescents. Glutamatergic and GABAergic abnormalities potentially underlie cingulate dysfunction in adolescent chronic marijuana users, and the opportunity for testing suitable pharmacologic treatments with a non-invasive pharmacodynamic evaluation exists.