# Presentation: 670036

## Perspectives fromNorth America: Recent Findings from Inhalant Abuse Research in the United States

- Matthew O. Howard, Ph.D.
- Professor of Social Work & Psychiatry
- The University of Michigan
- June 16, 2007

## Overview

- Epidemiological Findings
- Typological Research
- Correlates and Consequences of Use
- An Agenda for North American Inhalant Abuse Research

## Epidemiological Findings

## Slide 4

## NESARC in a Nutshell

- 3-wave survey of 43,093 U.S. residents
- Age 18 and older
- Civilian, non-institutionalized adult household population
- Multi-stage cluster sampling design
- Overall response rate of 82%

## NESARC in a Nutshell

- Provides lifetime and annual DSM-IV diagnoses
- Assesses most Axis II disorders
- Use of single, omnibus inhalant item

## Characteristics of Inhalant Users

- 2% (N=664) Lifetime prevalence of inhalant use
- ≈60% had onset before age 18
- 82% Caucasian
- 41% had high school education or less
- 53% reported a total family income less than $40,000/yr** **

## Prevalence & Correlates of Psychiatric Disorders in US Inhalant Users

## Prevalence & Correlates of Psychiatric Disorders in US Inhalant Users

_**Mood Disorders**_
- Major Depression 				40.8%
- Mania  		15.4%
- Dysthymia  	17.4%
- Any Mood Disorder 				48.4%

_**Anxiety Disorders**_
- GAD 		10.7%
- So Phobia 	12.1%
- Specific Phobia	17.7%
- PD w/wo Agor	18.0%
- Any Anxiety Disorder				36.3%

## Prevalence & Correlates of Psychiatric Disorders in US Inhalant Users

_**Personality Disorders**_
- ASPD	32.1%
- OC		17.2%
- Paranoid	13.1%
- Any PD	45.1%

_**Comorbidity**_
- 1-2 diagnoses	35.5%
- 3-5 diagnoses 	21.3%
- 6+ diagnoses 	13.1%

## Correlates of Psychiatric Disorders in Lifetime Inhalant Users 

- Female
- Caucasian
- Age of onset of inhalant use < 18
- Low annual family income
- History of substance abuse treatment
- Family history of major depression/APSD

## Temporal Relationships Between Disorders

- Inhalant use and inhalant use disorders precede development of all disorders but Sp and So Phobias
- Rates of past year mood (26%) and anxiety (25%) diagnoses were also high

## Prevalence of Substance Use Disorders in US Inhalant Users 

**	****	****	****	****	****	****  **Lifetime 	  Annual
- 						_Prevalence__	__Prevalence_
- Alcohol				   87.3%	   37.9%
- Nicotine				   57.8%	   44.5%
- Inhalants				   19.4%	     1.4%
- Cannabis				   67.8%	   15.4%
- Cocaine				   35.4%	     5.0%
- Heroin				  	     4.8%	      <1%
- Hallucinogens				   30.6%	     2.6%
- Pain Relievers/Opioids		   20.0%	     3.3%
- Amphetamines/Stimulants		   28.2%	     2.4%

- Source: Wu, L.T., & _Howard_, M.O. (under review). Substance use disorders among inhalant users: Findings from the National Epidemiologic Survey on Alcohol and Related Conditions. *Drug and Alcohol Dependence.*

## Prevalence of Comorbid SUDs in Lifetime Inhalant Users

**	****	****	****	****  **Lifetime 		  Annual
- 				_Prevalence__	__	__Prevalence_
- 0 SUDs		     4.0%		   38.0%
- 1-2 SUDs		   33.1%		   50.2%
- 3-5 SUDs		   40.1%		3+ 11.8%
- 6-11 SUDs		   22.8%

## Characteristics of Inhalant Use/Users 

- 19.4% met DSM-IV criteria for an IUD
- 88.4% of diagnoses were for Abuse not Dependence
- 10.8% had onset before age 13
- 48.2% had onset between ages 13 and 17
- ≈7% reported lifetime substance abuse treatment
- Tobacco, alcohol, and marijuana use typically preceded inhalant abuse

## Alcohol, Illicit Drug & Nicotine Use Disorders Among Lifetime Inhalant Users 

- Characteristics that generally predicted higher risk for SUDs:
- Younger Age
- Male Gender
- Not being married
- Lower annual family incomes

## Alcohol, Illicit Drug & Nicotine Use Disorders Among Lifetime Inhalant Users 

- Factors that predicted development of an IUD:
- Low education status
- Early onset of inhalant use
- Lifetime SUD treatment

## Summary of Epidemiological Findings 

- Lifetime inhalant users in the US suffer from exorbitantly high rates of comorbid psychiatric and polysubstance use disorders/Few Txed
- One-fifth of inhalant users eventually meet DSM-IV criteria for an IUD
- Among inhalant users, mood, anxiety, and SUDs appear to exert their effects across the life course

## Summary of Epidemiological Findings 

- Low SES and disadvantaged social status of inhalant users confounds their life circumstances
- Survey and ethnographic studies are needed to examine the nature of inhalant use in select high risk subpopulations

## Typological Research

## Latent Class & Latent Profile Analyses 

- Perron, Vaughn, & Howard (in press).  Reasons for Using Inhalants: Evidence for Discrete Classes in a Sample of Incarcerated Adolescents.  *Journal of Substance Abuse Treatment*.
- Vaughn, Perron, & Howard (in press).  Variations in Social Contexts and their Effect on Adolescent Inhalant Use.  *Drug and Alcohol Dependence.*

## Neuropsychiatric Impairments in Adolescent Inhalant Users

- NIDA DA015929

## Study Characteristics

- N = 723
- 13-17 year-olds incarcerated in 32 MO facilities
- 98% response rate
- 87% Male
- 33% African-American; 55.4% Caucasian
- 51.4% with a history of physician-diagnosed mental illness
- 38.0% reported lifetime inhalant use
- polyinhalant use prevalent

## Latent Profile Analysis of Reasons for Use

- Focuses on the 277 youth reporting lifetime inhalant use
- Aim: to identify subgroups of inhalant users based on their reasons for use
- Results indicated support for a 3-class solution
- Classes differed significantly across clinical but not demographic variables

## Reasons for Using Inhalants

| Reason | Mean | SD |
| --- | --- | --- |
| Curious about effects | 2.76 | 1.07 |
| Feeling bored | 2.38 | 1.27 |
| Easier to get than other drugs | 2.25 | 1.41 |
| Fun to use | 2.03 | 1.33 |
| To relax | 1.89 | 1.28 |
| Not dangerous | 1.82 | 1.30 |
| To forget about troubles | 1.69 | 1.40 |

## Reasons for Using Inhalants

| Reason | Mean | SD |
| --- | --- | --- |
| Peer pressure | 1.60 | 1.37 |
| Feeling sad | 1.38 | 1.30 |
| Feeling anxious | 1.29 | 1.21 |
| To impress others | 1.26 | 1.23 |
| Angry at someone | 1.24 | 1.26 |
| Family problems | 1.23 | 1.29 |
| Angry at self | 1.10 | 1.17 |
| Like more than other drugs | 0.92 | 1.05 |

## Empirical Fit of Models & Class Sizes

| Class Solution | BIC | Entropy | Class Size
N (%) |
| --- | --- | --- | --- |
| 1 Class | 13861.47 | NA | 277 (100) |
| 2 Classes | 13027.28 | 0.925 | 169 (61.8)
108 (39.2) |
| 3 Classes | 12766.44 | 0.903 | 85 (30.6)
122 (44.1)
70 (25.3) |

## Empirical Fit of Models & Class Sizes

| Class Solution | BIC | Entropy | Class Size
N (%) |
| --- | --- | --- | --- |
| 4 Classes | 12725.30 | 0.902 | 61 (22.0)
76 (27.6)
86 (31.1)
53 (19.3) |

## Empirical Fit of Models & Class Sizes

| Class Solution | BIC | Entropy | Class Size
N (%) |
| --- | --- | --- | --- |
| 5 Classes | 12725.96 | 0.912 | 77 (27.7)
50 (17.9)
69 (24.9)
50 (18.2)
31 (11.3) |

## Reasons for Using Inhalants

## Tests of Association Among 3 Class Solution

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value (η2) |
| --- | --- | --- | --- | --- | --- |
| Sucidality
Index | 2.86 (2.43) | 2.98 (2.41) | 4.27 (2.21) | 8.42b,c | <.001 (.06) |
| Substance Use Index | 4.14 (2.35) | 5.31 (1.94) | 6.24 (.159) | 21.34a,b,c | <.001 (.13) |
| Depression (BSI) | 4.73 (5.27) | 5.49 (4.70) | 8.91 (6.38) | 13.25b,c | <.001 (.09) |
| Anxiety (BSI) | 4.16 (4.39) | 4.90 (4.18) | 9.03 (6.30) | 22.30b,c | <.001 (.14) |

## Tests of Association Among 3 Class Solution

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value (η2) |
| --- | --- | --- | --- | --- | --- |
| Paranoid Ideation (BSI) | 6.36 (4.77) | 6.59 (4.44) | 9.29 (4.69) | 9.64b,c | <.001 (.07) |
| Psychoticism (BSI) | 3.39 (3.69) | 4.29 (4.07) | 6.87 (5.04) | 13.82b,c | <.001 (.09) |
| Global Severity Index | 42.98 (32.84) | 48.52 (30.38) | 76.71 (43.58) | 20.54b,c | <.001 (.13) |
| Externalizing Behaviors | 23.14 (16.05) | 27.41 (19.50) | 33.06 (19.67) | 5.41b | <.001 (.04) |

## Tests of Association Among 3 Class Solution

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value (η2) |
| --- | --- | --- | --- | --- | --- |
| Polysubstance Use  | 34.02 (21.84) | 36.16 (19.57) | 42.67 (22.60) | 3.46b | .03 (.02) |

- Dunnett’s post-hoc comparisons conducted for all ANOVAs: a = Classes 1 and 2 are different; b = Classes 1 and 3 are different; c = Classes 2 and 3 are different.

## Conclusions

- Significant heterogeneity in reasons for inhalant use among adolescents
- Approximately one-quarter of adolescent inhalant users reported high levels of inhalant use in relation to negative emotional states and interpersonal conflict

## Conclusions

- Class 3 inhalant users exhibit high levels of internalizing and externalizing symptoms and high levels of drug use, polyinhalant use, and other problems relative to the other two classes of inhalant users
- Future research and clinical work with inhalant abusers should attend carefully to reasons for inhalant use

## Latent Profile Analysis of Peer Contexts

- Aim: to identify specific subgroups of adolescents based on contextual effects surrounding inhalant use episodes
- 9-item scale with 0 (Never) to 3 (Always)
- Lifetime inhalant users were asked to indicate “how often they had used inhalants when...”
- A 3-class solution was conceptually the most meaningful and parsimonious

## Peer Context Items

| Effect | Mean | SD |
| --- | --- | --- |
| Someone offered inhalants and felt awkward refusing them. | 0.89 | 0.99 |
| Met with friends and wanted to have a good time. | 1.20 | 1.07 |
| With friends and suggested you go somewhere and use inhalants. | 0.92 | 1.04 |
| Others in the same room were using inhalants and you felt expected to join in. | 1.03 | 1.09 |

## Peer Context Items

| Effect | Mean | SD |
| --- | --- | --- |
| With friends and wanted to increase your enjoyment. | 1.10 | 1.10 |
| Heard someone talking about their past experiences with inhalants. | 0.72 | 0.92 |
| Pressured to use inhalants and felt you couldn’t refuse. | 1.69 | 1.40 |
| Wanted to celebrate with a friend. | 0.65 | 0.97 |
| With a group of people and everyone was using inhalants. | 0.92 | 1.06 |

## Latent Profile Analysis

| Classes | LL | BIC (LL) | Npar | Class error | Entropy |
| --- | --- | --- | --- | --- | --- |
| 1 | -3089.82 | 6331.69 | 27 | 0.00 | NA |
| 2 | -2656.67 | 5521.68 | 37 | 0.02 | 0.92 |
| 3 | -2570.90 | 5406.47 | 47 | 0.06 | 0.86 |
| 4 | -2539.66 | 5400.31 | 57 | 0.09 | 0.81 |

## Context in Which Inhalants Used

## Comparing Classes Derived from Peer Context Measures

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value |
| --- | --- | --- | --- | --- | --- |
| Suicidality Index | 3.26 (2.44) | 3.81 (2.34) | 2.67 (2.40) | 4.94c | .008 |
| D & A Use Problems Idx. | 5.50 (1.94) | 5.82 (1.85) | 4.13 (2.27) | 17.37b,c | <.001 |
| Depression (BSI) | 5.34 (5.35) | 7.90 (5.69) | 5.22 (5.27) | 6.95a,c | <.001 |
| Anxiety (BSI) | 5.21 (4.98) | 7.66 (5.60) | 4.30 (4.47) | 10.47a,c | <.001 |

## Comparing Classes Derived from Peer Context Measures

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value |
| --- | --- | --- | --- | --- | --- |
| Paranoid Ideation (BSI) | 6.56 (4.57) | 8.85 (4.86) | 6.25 (4.38) | 8.46a,c | <.001 |
| Psychoticism (BSI) | 4.22 (4.41) | 6.17 (4.66) | 3.64 (3.73) | 8.41a,c | <.001 |
| Global Severity Index | 48.78 (34.33) | 69.36 (40.33) | 44.08 (32.13) | 12.58a,c | <.001 |
| Externalizing Behaviors | 26.96 (20.02) | 33.44 (17.99) | 21.80 (16.57) | 8.78a,c | <.001 |

## Comparing Classes Derived from Peer Context Measures

|  | Class 1
Mean (SD) | Class 2
Mean (SD) | Class 3
Mean (SD) | 
F statistic | 
P value |
| --- | --- | --- | --- | --- | --- |
| Fearlessness (PPI-SF) | 25.78 (5.74) | 27.77 (5.57) | 25.37 (6.34) | 4.24c | .01 |
| Impulsivity (ASPD) | 8.97 (2.54) | 9.62 (2.58) | 8.36 (2.36) | 5.56c | .004 |
| Past-Year Substance Use | 37.99 (22.17) | 41.93 (20.09) | 30.75 (19.91) | 3.46c | .002 |

- Dunnett’s post-hoc comparisons conducted for all ANOVAs: a = Classes 1 and 2 are different; b = Classes 1 and 3 are different; c = Classes 2 and 3 are different.

## Future Directions in Typological Research 

- Nationally-representative typologies
- Typologies based on reasons for and timing of desistance
- Typologies based on multiple measures of inhalant use
- Subgroup specific typologies

## Correlates and Consequences of Inhalant Use 

## Inhalant Use & Suicidality

## Study Aims and Findings 

- Aims: To investigate the relationship between suicidal ideation/suicide attempts and different levels of inhalant use
- 33.1% of youth reported a history of solvent use
- ≈12% of boys and 17% of girls developed an IUD
- ≈25% of the sample had attempted suicide

## Bivariate Relationship between Inhalant Use and Suicidality 

|  | No use | Use only | Abuse or Dependence | χ2a | pb |
| --- | --- | --- | --- | --- | --- |
| Ideationc (median) |  |  |  |  |  |
| All | 0 | 2 | 5 | 93.7 | <.001 |
| Boys | 0 | 2 | 5 | 72.3 | <.001 |
| Girls | 2 | 5 | 5 | 21.9 | <.001 |

- a For continuously measured ideation variable, Pearson’s chi-square reported for nonparametric Kruskal-Wallis test.
- b Using Bonferonni’s correction for multiple comparison, the threshold for statistical significance in this group of comparisons is .008 (.05/6).
- c Range 0 – 5.

## Bivariate Relationship between Inhalant Use and Suicidality 

|  | No use | Use only | Abuse or Dependence | χ2a | pb |
| --- | --- | --- | --- | --- | --- |
| Attemptd (%) |  |  |  |  |  |
| All | 17.0 | 30.2 | 63.3 | 88.1 | <.001 |
| Boys | 13.7 | 26.0 | 59.5 | 79.5 | <.001 |
| Girls | 40.0 | 61.1 | 81.3 | 9.5 | .009 |

- a For continuously measured ideation variable, Pearson’s chi-square reported for nonparametric Kruskal-Wallis test.
- b Using Bonferonni’s correction for multiple comparison, the threshold for statistical significance in this group of comparisons is .008 (.05/6).
- d Measured dichotomously.  Proportion of attempters reported for each level of inhalant use.

## Suicidality Regression Models

| Variable | Ideation (range, 0-5)b |  |  |  | Attempt (yes/no)c |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |    b |  | 95% CI |  | OR |  | 95% CI |
| Inhalant use |  |  |  |  |  |  |  |
| None (ref.) | - | - |  | - |  | - |  |
| Use only | 1.36** | .47 to 2.24 |  | 1.41 |  | .84 to 2.37 |  |
| Abuse/
dependence | 1.46** | .52 to 2.40 |  | 5.13*** |  | 2.73 to 9.65 |  |
| Male gender | -.61*** | -1.06 to -.15 |  | 3.79*** |  | 2.24 to 6.42 |  |
| Gender x Use | -1.04* | -1.97 to -.11 |  | NA |  | NA |  |

## Suicidality Regression Models

| Variable | Ideation (range, 0-5)b |  |  |  | Attempt (yes/no)c |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |    b |  | 95% CI |  | OR |  | 95% CI |
| Race |  |  |  |  |  |  |  |
| White (ref.) | - | - |  | - |  | - |  |
| Black | -.83*** | -1.16 to -.51 |  | .41*** |  | .23 to .75 |  |
| Hispanic | -.60 | -1.24 to .04 |  | .24 |  | .08 to .74 |  |
| Other | .52* | .06 to .98 |  | 1.51 |  | .77 to 2.94 |  |

## Suicidality Regression Models

| Variable | Ideation (range, 0-5)b |  |  |  | Attempt (yes/no)c |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |    b |  | 95% CI |  | OR |  | 95% CI |
| Psychiatric symptoms | .02*** | .02 to .03 |  | 1.02*** |  | 1.01 to 1.03 |  |
| Trauma | .10* | .01 to .19 |  | 1.20* |  | 1.03 to 1.39 |  |

- a Only predictors with statistical significance in at least one model are shown in table.  The linear regression model also contained an interaction term for gender and solvent use/dependence.
- b Multiple linear regression; model *F*(13,697) = 32.1, p <.001, adjusted R2 = .36.
- c Logistic regression; model χ2 (11) = 199.3, p <.001, pseudo-R2 = .25.
- *p<.05; **p<.01; ***p<.001.

## Conclusions

- Youth with Inhalant Use Disorders are at high risk for suicide attempts
- The mechanism for such enhanced risk is presently unclear
- Adolescent inhalant users should be screened for suicidality

## Inhalants, Heroin & IV Drug Use

## Study Background

- Aim: to examine the prevalence of heroin/IVDU use among adolescents in the U.S. and the relationship of inhalant use to such use
- N = 35, 913
- 13-17 year-olds participating in the NSDUH
- Data collected in 2002/2003

## Study Results 

- Rates of lifetime heroin use and lifetime IVDU were notably elevated in:
- early-onset inhalant users
- inhalant users who had used 3+ inhalants
- youth who had initiated inhalant **and** marijuana use

## Study Results 

- In multiple logistic regression analyses, female respondents, school dropouts, delinquent youth, and youth who had initiated inhalant and marijuana use were significantly more likely to report heroin and IVDU than their counterparts

## Conclusions

- More studies are needed examining health/mental health consequences of inhalant use/IUDs
- Longitudinal studies would be particularly helpful in sorting out the causal role that inhalant use plays in the development of these disorders

## Recommendations for Future North American Inhalant Research 

## Recommendations for Studies

- Develop nationally-representative and subgroup empirically-based taxonomies of inhalant users
- Describe the natural history of Inhalant Use Disorders (initiation, escalation, onset of IUDs, etc.)
- Estimate the prevalence of psychiatric disorders in individuals with lifetime inhalant use/IUDs

## Recommendations for Studies

- Evaluate the contribution of inhalant use and Inhalant Use Disorders to:
- development of medical conditions/long-term and acute
- adverse social consequences
- health/mental health-related functional impairments

## Recommendations for Studies

- Describe the substance-related/general medical health care treatment experiences of inhalant users including types, rates, and perceived barriers
- More clinical and epidemiological studies on nitrite, nitrous oxide, and asthma inhaler abuse
- Studies of the clinical features of IUDs such as withdrawal