In brief
This systematic review of 26 studies (2009-2019) found that adults with autism spectrum disorder show increased, not decreased, vulnerability to substance use and substance use disorder, challenging the old assumption that ASD is protective. The pattern was less consistent for adolescents, and routine screening for...
What this article is about
Quick Answer
This systematic review of 26 studies (2009-2019) found that adults with autism spectrum disorder show increased, not decreased, vulnerability to substance use and substance use disorder, challenging the old assumption that ASD is protective. The pattern was less consistent for adolescents, and routine screening for substance use in ASD patients remains uncommon, suggesting many cases go undiagnosed.
Student takeaways
Key Takeaways
- Of the 26 included studies, 21 found that people with ASD have an increased vulnerability to substance use and substance use disorder (SUD) compared with the general population, contradicting the historical assumption that ASD is protective against substance use.
- Five studies found a decreased or no elevated risk of substance use in ASD populations; the authors noted that three of these (Ramos et al. 2013, Mangerud et al. 2014, Schapir et al. 2016) used adolescent or young-adult samples, suggesting the increased-risk finding may hold mainly for adults.
- Among studies that specified substance types, alcohol was the most commonly used substance, followed by cannabis, with lower reported use of illegal 'hard' drugs, which the authors link to the social/communication skills typically needed to obtain illegal substances.
- Vulnerability to substance use in ASD was associated with a combination of environmental/social factors (isolation, coping with social anxiety and overstimulation), neurocognitive factors (executive-functioning deficits affecting risk perception and impulse control), and genetic/neurological overlap with ADHD (including a candidate role for the AUTS2 gene in heroin and alcohol dependence).
- Screening for substance use disorder is not a routine part of clinical assessment for people with ASD (unlike for conditions such as schizophrenia), which the authors argue likely leads to underdiagnosis of SUD in this population.
Student summary
Why This Research Matters
For years, autism spectrum disorder (ASD) was assumed to protect people from substance use — the thinking was that social difficulties would keep autistic people away from the peer settings where drinking and drug use usually start. This systematic literature review by Helandri Haasbroek and Neo Morojele, published in the Review Journal of Autism and Developmental Disorders (2022), tested that assumption by pulling together 26 primary studies published between 2009 and 2019 on ASD and substance use in adults and adolescents.
The researchers searched seven databases (SpringerLink, ResearchGate, Cengage Learning, the Journal of Autism and Developmental Disorders, PubMed, Medline, and PsycINFO) using autism and substance-use search terms, screened 671 unique records after removing duplicates, and ended with 26 studies that met their inclusion criteria: primary research in English on adults or adolescents (age 11+) with ASD and either recreational substance use or misuse of prescribed substances.
The overall picture that emerged was more nuanced than a simple yes-or-no answer. Twenty-one of the 26 studies found that people with ASD were more vulnerable to substance use and substance use disorder (SUD) than the general population — not less. But five studies (Hofvander et al. 2009, Ramos et al. 2013, Mangerud et al. 2014, Schapir et al. 2016, and Churchard et al. 2019) found the opposite or no elevated risk. The authors drew particular attention to an age pattern in three of those five: Ramos, Mangerud, and Schapir all studied adolescent or young-adult samples. (The other two were different cases — Hofvander found autistic people no more at risk than other psychiatric patients, and Churchard studied a homeless population.) On this basis the authors concluded that ASD may not be protective for adults, while the picture for younger people is genuinely unclear and possibly different, since adolescents with ASD may be more socially sheltered and have less access to substances through peers.
When substance types were reported, alcohol was the most common substance used, followed by cannabis, with far less use of harder illegal drugs — a pattern the authors linked back to ASD's social-communication difficulties, since obtaining illegal drugs typically requires more complex social networking than buying alcohol or cannabis.
The review also looked at why this vulnerability might exist. Three overlapping explanations came up across the studies: environmental and social factors (loneliness, isolation, and using substances to cope with overstimulation or to feel more able to socialize), executive-functioning deficits (trouble with planning, weighing consequences, and breaking habitual behaviour, which may make it harder to foresee the downsides of substance use), and genetic/neurological overlap (shared genetic risk factors between ASD, ADHD, and SUD, including a possible role for the AUTS2 gene in heroin and alcohol dependence susceptibility). High rates of co-occurring depression, anxiety, and ADHD were repeatedly flagged as compounding the risk.
A recurring and troubling theme was that routine clinical screening for substance use is not standard practice for people with ASD, unlike for other psychiatric conditions such as schizophrenia. Because substance-related symptoms can look similar to autism-related traits (poor self-regulation, executive-function struggles), clinicians may miss SUD in autistic patients entirely. One included study on treatment (using modified cognitive behavioural therapy) showed some real promise, but also revealed that ASD-specific communication needs made standard SUD treatment approaches harder to deliver effectively.
For future nurses, the review is a reminder not to assume a patient's diagnosis rules out other risks. It points to the importance of routinely and non-judgmentally screening ASD patients for substance use, recognizing the specific stressors (isolation, sensory overload, social anxiety) that may drive use in this population, and being aware that standard SUD interventions may need real adaptation to work for autistic clients. The authors are careful to flag that their evidence base is limited — mostly small, cross-sectional studies from wealthy Western countries — so it should inform awareness and further research rather than firm clinical protocols.
Source abstract
Study Overview
Autism spectrum disorder has often been assumed to be a protective factor against substance use, yet the extent of substance use in this population has been difficult to determine as limited research has been done on these interacting variables. This systematic literature review examined 26 studies published between 2009 and 2019 to uncover the relationship between autism spectrum disorder and substance use. The types of participants included from the primary studies are adults and adolescents. A significant indication that this population is more susceptible to substance use and related disorders was found, yet this may only remain true for adults. Various interacting environmental and genetic/neurological factors combine and may contribute towards this vulnerability such as feelings of isolation, deficits in executive functioning and genetic heritability. High comorbidity rates of depression, anxiety disorders and attention deficit/hyperactivity disorder may further strengthen this vulnerability. Screening for substance use in these patients is not a common practice and the treatment of substance use disorder remains a challenge suggesting that many individuals may remain underdiagnosed. This research paper thus demonstrates the need and importance of more primary research to be done and for greater awareness of this vulnerability within mental health settings.
Evidence appraisal
Main Findings
- Of the 26 included studies, 21 found that people with ASD have an increased vulnerability to substance use and substance use disorder (SUD) compared with the general population, contradicting the historical assumption that ASD is protective against substance use.
- Five studies found a decreased or no elevated risk of substance use in ASD populations; the authors noted that three of these (Ramos et al. 2013, Mangerud et al. 2014, Schapir et al. 2016) used adolescent or young-adult samples, suggesting the increased-risk finding may hold mainly for adults.
- Among studies that specified substance types, alcohol was the most commonly used substance, followed by cannabis, with lower reported use of illegal 'hard' drugs, which the authors link to the social/communication skills typically needed to obtain illegal substances.
- Vulnerability to substance use in ASD was associated with a combination of environmental/social factors (isolation, coping with social anxiety and overstimulation), neurocognitive factors (executive-functioning deficits affecting risk perception and impulse control), and genetic/neurological overlap with ADHD (including a candidate role for the AUTS2 gene in heroin and alcohol dependence).
- Screening for substance use disorder is not a routine part of clinical assessment for people with ASD (unlike for conditions such as schizophrenia), which the authors argue likely leads to underdiagnosis of SUD in this population.
Practice transfer
Clinical Relevance
- Nurses and clinicians working with autistic adults should not assume that an ASD diagnosis rules out substance use; routine, non-judgmental screening for substance use should be considered as part of standard psychiatric and primary care assessment, similar to practices used for other psychiatric conditions.
- Because comorbid depression, anxiety, and ADHD raise the risk of substance use in people with ASD, clinicians should treat these co-occurring conditions as flags for closer substance-use assessment rather than treating them in isolation.
- Substance intoxication or withdrawal can present with behaviours (poor self-regulation, reduced inhibitory control) that resemble autistic traits, so clinicians should consider substance use as a differential when unexplained behavioural changes appear in ASD patients.
- Standard substance use disorder treatments, including group-based therapy, may need modification for autistic clients — for example, adapting communication style and allowing more session time — since intensive unstructured social interaction can itself be a barrier to engagement.
- Because loneliness, social isolation, and difficulty coping with overstimulation were repeatedly identified as drivers of substance use in ASD, care plans should incorporate social support, structure, and coping-skills components alongside any substance use treatment.
Faculty notes
Educational Relevance
This appraisal-ready systematic literature review (Haasbroek & Morojele, 2022, Review Journal of Autism and Developmental Disorders 9:1-20) synthesizes 26 primary studies (2009-2019) on the ASD-substance use relationship in adults and adolescents, updating and expanding a 2016 review by Arnevik and Helverschou (18 papers). It is a strong teaching example of PRISMA-guided review methodology paired with a mixed evidence base — useful for practicing critical appraisal rather than accepting a tidy conclusion.
Methodologically, the authors document a full PRISMA flow: 940 records identified across seven databases (search concluded May 2019), 671 remaining after de-duplication, and 26 finally included. Inclusion criteria required English-language primary research (qualitative, quantitative, or mixed methods; including case studies) on participants aged 11+ with ASD, involving recreational substance use or prescribed-substance misuse. Exclusions covered under-11 populations, maternal prenatal substance exposure literature, caregiver substance use, non-substance addictions (gambling, internet), and secondary literature reviews. Instructors can use the published PRISMA diagram and inclusion/exclusion table as a concrete worked example.
Study characteristics are worth flagging for discussion: 20 of 26 studies originated in Europe (predominantly the Netherlands and Sweden), only 6 elsewhere (USA, China, Australia); only 3 were longitudinal; sample sizes ranged from single-digit case studies to a 26,986-participant Swedish national cohort; all studies skewed heavily male; and 11 of 26 studies had overlapping ADHD/ASD samples, complicating attribution of risk to ASD specifically.
The central finding — heterogeneous across the literature — is that 21 of 26 studies found increased SUD/substance-use vulnerability in ASD populations, while 5 (Hofvander et al. 2009; Ramos et al. 2013; Mangerud et al. 2014; Schapir et al. 2016; Churchard et al. 2019) found no elevated or decreased risk. The authors' key interpretive contribution is noting that three of these five discordant studies (Ramos et al. 2013, Mangerud et al. 2014, Schapir et al. 2016) used adolescent or young-adult samples, suggesting the vulnerability effect may be age-dependent (the other two differ: Hofvander found no elevated risk relative to other psychiatric populations, and Churchard studied a homeless sample). This age-dependence hypothesis is the paper's most novel claim and a good discussion point on how reviews generate hypotheses — while modeling caution, since a pattern drawn from three studies is suggestive, not definitive.
Three explanatory mechanisms are proposed and can be mapped directly to nursing curricula on comorbidity and biopsychosocial models: (1) environmental/social factors — isolation, using substances to cope with communication anxiety or sensory overload, or to feel able to socialize; (2) neurocognitive vulnerability — executive-functioning deficits impairing risk assessment and impulse control; and (3) genetic/neurological overlap with ADHD, including candidate-gene work (AUTS2) linking an ASD susceptibility locus to heroin/alcohol dependence. Instructors should note the genetic evidence is thin (essentially one candidate-gene study) and should be presented as hypothesis-generating, not established mechanism.
Clinically, the review's strongest practice-relevant finding is that SUD screening is not routine in ASD care (Palmqvist et al. 2014, Sweden), unlike schizophrenia, creating diagnostic-overshadowing risk since intoxication effects can mimic autistic traits. The Helverschou et al. (2019) case series (n=4) piloting modified CBT for co-occurring ASD/SUD is the only treatment-outcome study in the set and is appropriately underpowered but pedagogically useful for discussing tailored intervention design and small-n exploratory trial limitations.
Suggested classroom uses: (1) PRISMA/appraisal exercise using the published flow diagram and Table 2 summary; (2) discussion of confounding by ADHD comorbidity across 11/26 studies; (3) critique of cross-sectional predominance and its limits for causal direction and age-of-onset inference; (4) discussion of diagnostic overshadowing and screening equity across psychiatric populations; (5) contrast of DSM-IV subtype terminology (Asperger's, PDD-NOS) with DSM-5 unified ASD criteria and the comparability problems this creates across the included literature.
Critical appraisal
Limitations
- Most of the 26 included studies were cross-sectional (only 3 were longitudinal), which prevents the authors from establishing whether ASD causes increased substance use risk or simply co-occurs with it.
- Twenty of the 26 studies originated in European countries and the rest largely from other high-income nations (USA, Australia) with one from China; findings may not generalize to lower-income or non-Western populations with different access to healthcare and different substance use environments.
- Sample sizes varied enormously, from single-digit case studies and small clinical samples (as few as 4-8 participants) to a national cohort of nearly 27,000; several of the more striking findings come from very small samples that the original study authors themselves flagged as preliminary.
Classroom use
Discussion Questions
- Why might ASD have historically been assumed to be protective against substance use, and what does this review suggest is wrong with that assumption for adults specifically?
- The review noted that three of the five studies showing decreased/no increased risk (Ramos, Mangerud, Schapir) were conducted with adolescent or young-adult samples. What competing explanations could account for this age-related pattern besides a true developmental difference in risk?
- How might the predominance of alcohol and cannabis use (versus illegal 'hard' drugs) in ASD populations relate to the social and communication challenges characteristic of autism?
- What ethical and practical challenges arise when trying to introduce routine substance use screening into standard ASD clinical care, and how might nurses working in Canadian mental health and primary-care settings help address them within their scope of practice?
- How could 'diagnostic overshadowing' (where substance-related symptoms are mistaken for autism traits) lead to underdiagnosis of SUD in ASD patients, and what assessment strategies could reduce this risk?
- Given that 11 of the 26 studies included participants with both ASD and ADHD, how confident can we be that the findings reflect ASD-specific risk rather than ADHD or shared risk factors?
- The Helverschou et al. (2019) case series used modified CBT with only 4 participants. What does this study's design tell you about the strength of evidence for ASD-adapted SUD treatment, and what would a stronger study look like?
- How do loneliness, social isolation, and executive-functioning deficits interact, according to this review, to create a 'vicious cycle' that perpetuates substance use in people with ASD?
- The review notes that DSM-5 replaced subtypes like Asperger's syndrome and PDD-NOS with a single ASD category. How might this change complicate interpreting and comparing older versus newer research on ASD and substance use?
- What would you want to know from a patient's family or social history to assess their risk of substance use if they have ASD, based on the environmental risk factors identified in this review?
Knowledge check
Quiz
1. How many primary studies were included in this systematic literature review?
- 18
- 21
- 26
- 34
Rationale: The abstract and full text state the review 'examined 26 studies published between 2009 and 2019 to uncover the relationship between autism spectrum disorder and substance use.'
2. According to this review, what proportion of the 26 studies found that ASD populations had an increased vulnerability to substance use or SUD?
- 5 of 26 studies
- 13 of 26 studies
- 21 of 26 studies
- All 26 studies
Rationale: The full text states: 'The rest of the 21 studies picked up on a distinct pattern suggesting that individuals with ASD may use more or be more at risk for abusing substances,' with the remaining 5 studies finding no increased or a decreased risk.
3. Among the studies that found decreased or no increased substance use risk in ASD, what characteristic did the authors highlight in several of them to explain the age-dependent pattern?
- They were all conducted in the United States
- Their samples consisted of adolescents or young adults
- They all used genetic testing methods
- They all had sample sizes over 1,000
Rationale: The authors note that three of the five discordant studies (Ramos et al. 2013 and Mangerud et al. 2014 studied adolescents, and Schapir et al. 2016 used a young sample with a mean age of 23), which underpins their suggestion that the elevated risk may be specific to adults.
4. Which substance was most commonly reported as used by ASD populations across the studies that specified substance types?
- Cannabis
- Heroin
- Alcohol
- Cocaine
Rationale: The discussion states: 'Alcohol use and related disorders seemed to be the most common and the highest reported substance of choice according to the given studies, followed by cannabis.'
5. How many databases were searched to identify studies for this systematic literature review?
- Three
- Five
- Seven
- Ten
Rationale: The methods section states seven databases were searched: 'SpringerLink, Research Gate, Cengage Learning, Journal of Autism and Developmental Disorders, PubMed, Medline and Psych Info.'
6. According to Palmqvist et al. (2014), as discussed in this review, what is a key gap in current clinical practice for people with ASD?
- Overly frequent and invasive substance use testing
- Screening for substance use disorder is not a common clinical routine
- Excessive use of group therapy for ASD patients
- Mandatory genetic testing for all ASD patients
Rationale: The abstract and discussion state: 'Screening for substance use in these patients is not a common practice...suggesting that many individuals may remain underdiagnosed,' citing Palmqvist et al. (2014).
7. Which gene was studied in relation to ASD and a possible genetic vulnerability to heroin and alcohol dependence?
- AUTS2
- SLC6A4
- MECP2
- SHANK3
Rationale: The full text discusses Dang et al. (2014): 'The Evidence for the Contribution of the Autism Susceptibility Candidate 2 (AUTS2) Gene in Heroin Dependence Susceptibility,' noting it 'may also act as a vulnerability gene for heroin and alcohol dependence.'
8. What treatment approach was piloted with autistic adults who also had substance use disorder in the Helverschou et al. (2019) study discussed in this review?
- MDMA-assisted psychotherapy
- Cognitive behavioural therapy (CBT) modified for ASD
- Standard unmodified group therapy
- Medication-only treatment with no psychotherapy
Rationale: The full text states: 'four male patients with both ASD and SUD were given cognitive behavioural therapy (CBT) for a minimum of 10 sessions to treat SUD. This therapy had been modified to accommodate the challenges that ASD may present.'
9. What was one of the main limitations of the primary studies identified by the review authors?
- Most studies were conducted in low-income developing countries
- Most studies were performed in first-world countries, mainly in Europe
- None of the studies included any male participants
- All studies used identical diagnostic criteria across decades
Rationale: The limitations section states: 'One of the biggest limitations of these studies has been that they were mostly performed in first-world countries, with European countries having most of the studies done.'
10. According to the review, why might people with ASD be more likely to use alcohol and cannabis rather than illegal 'hard' drugs?
- Alcohol and cannabis are cheaper than other substances in every country
- Obtaining illegal drugs typically requires complex social and communication skills that may be more challenging for people with ASD
- Hard drugs are not addictive for people with ASD
- There is no reported difference in substance preference for people with ASD
Rationale: The discussion states: 'individuals with ASD were less likely to use illegal drugs and more likely to use alcohol, which is legal, and cannabis...because the use of illegal drugs requires complex social and communication skills for the attainment of the drugs.'
Study cards
Flashcards
What was the main research question of this systematic literature review?
Whether and how autism spectrum disorder (ASD) is related to substance use and substance use disorder (SUD) in adults and adolescents.
How many studies were included in the final review, and over what time span were they published?
26 studies, published between 2009 and 2019.
How many databases were searched and how many total records were initially identified?
Seven databases were searched, yielding 940 initial records, reduced to 671 after removing duplicates.
What was the historical assumption about ASD and substance use that this review challenges?
That ASD was a protective factor against substance use, largely due to assumed social isolation reducing exposure to peer substance use.
What proportion of included studies found increased substance use vulnerability in ASD populations?
21 of the 26 studies found increased vulnerability; 5 found decreased or no increased risk.
What key age-related pattern did the authors identify among the studies with contrary findings?
Three of the five studies finding decreased/no increased risk (Ramos 2013, Mangerud 2014, Schapir 2016) used adolescent or young-adult samples, suggesting the elevated risk may be primarily an adult phenomenon.
Which substance was most frequently reported as used among ASD populations in the review?
Alcohol, followed by cannabis.
What are the three main categories of explanatory mechanisms proposed for ASD-related substance use vulnerability?
Environmental/social factors (isolation, coping), neurocognitive factors (executive-functioning deficits), and genetic/neurological overlap with ADHD.
What gene was studied as a possible shared genetic vulnerability factor for both ASD and substance dependence?
AUTS2 (autism susceptibility candidate 2 gene), linked to heroin and alcohol dependence susceptibility.
What comorbid psychiatric conditions were noted to further increase vulnerability to substance use in ASD?
Depression, anxiety disorders, and attention deficit/hyperactivity disorder (ADHD).
What did Palmqvist et al. (2014), cited in this review, find about clinical screening practices for SUD in ASD patients?
Screening for substance use disorder was not a routine part of clinical assessment for ASD patients, unlike for conditions such as schizophrenia.
What is 'diagnostic overshadowing' as it applies to ASD and substance use, based on this review?
The phenomenon where substance-related behavioural symptoms (e.g., poor self-regulation) are mistaken for autism traits, potentially causing SUD to go undetected.
What treatment study was highlighted as testing an intervention specifically for co-occurring ASD and SUD?
Helverschou et al. (2019), a small clinical explorative study using CBT modified for ASD with 4 male patients.
What outcome did the Helverschou et al. (2019) CBT study report?
Two of four participants ended substance use, one reduced use, and one remained heavily dependent on alcohol.
Why might illegal ('hard') drugs be less commonly used by people with ASD compared to alcohol or cannabis, according to this review?
Because obtaining illegal drugs typically requires more complex social and communication skills, which can be more challenging for people with ASD.
What percentage of the included studies were conducted in European countries?
20 of the 26 studies (roughly 77%) were conducted in European countries.
What is a key limitation regarding study design across the 26 included studies?
Most studies (23 of 26) were cross-sectional rather than longitudinal, limiting the ability to determine causal or age-of-onset relationships.
How did diagnostic terminology changes (DSM-IV to DSM-5) complicate this review's synthesis?
Older studies used now-obsolete ASD subtypes (e.g., Asperger's syndrome, PDD-NOS) that DSM-5 folded into a single ASD category, making comparison across studies difficult.
What gender pattern was observed across the included studies' samples?
All studies had male-dominant samples, consistent with ASD being more commonly diagnosed in males.
What is the main practical recommendation this review makes for mental health and nursing practice?
Greater awareness and routine screening for substance use vulnerability among people with ASD, alongside more primary research into this understudied comorbidity.
Search-ready answers
Frequently asked questions
Does having autism spectrum disorder protect someone from substance use?
No — this systematic review found that in adults, ASD is generally associated with increased, not decreased, vulnerability to substance use and substance use disorder, contradicting the older assumption that ASD is protective.
Are adolescents with autism also at higher risk of substance use, according to this review?
The evidence is less clear for adolescents. Among the five studies in this review that did not find an increased risk, three were conducted in adolescent or young-adult samples, which led the authors to suggest the elevated risk found in most studies may be more specific to adults.
What substances are most commonly used by people with autism spectrum disorder?
Among the studies that specified substance types, alcohol was the most commonly used, followed by cannabis, with lower reported use of illegal 'hard' drugs like heroin or cocaine.
Why might people with autism be vulnerable to substance use disorder?
This review identifies three overlapping contributors: social/environmental factors like isolation and coping with anxiety, executive-functioning deficits that impair risk assessment, and genetic/neurological overlap with ADHD and possible shared genetic risk factors.
Is substance use routinely screened for in people diagnosed with ASD?
No. This review cites research showing that, unlike conditions such as schizophrenia, routine clinical screening for substance use disorder is not standard practice for people with ASD, which may lead to underdiagnosis.
Can standard substance use disorder treatments work for people with autism?
The review discusses one small study using cognitive behavioural therapy modified for ASD, which showed some success but also highlighted that standard treatment approaches (like group therapy) may need adaptation for autistic clients' communication needs.
Is there a genetic link between autism and substance use disorder?
Preliminary evidence discussed in this review points to shared genetic overlap between ASD and ADHD, and one study identified a candidate gene (AUTS2) associated with both ASD and heroin/alcohol dependence susceptibility, though this evidence is limited and needs further research.
How many studies were reviewed in this systematic literature review on ASD and substance use?
The review analyzed 26 primary studies published between 2009 and 2019, drawn from 671 unique records identified across seven academic databases.
What role does comorbidity with depression, anxiety, or ADHD play in ASD and substance use?
The review notes that high rates of comorbid depression, anxiety disorders, and ADHD may further strengthen the vulnerability of people with ASD to substance use and related disorders.
What are the main limitations of this research on ASD and substance use?
Key limitations include a predominance of cross-sectional (non-longitudinal) studies, samples concentrated in European and other high-income countries, small and variable sample sizes, and overlapping ASD/ADHD samples that make it hard to isolate ASD-specific risk.