The authors have declared that no competing interests exist.
The Perspective section provides experts with a forum to comment on topical or controversial issues of broad interest.
DSM-5 has moved autism from the level of subgroups (“apples and oranges") to the prototypical level (“fruit"). But making progress in research, and ultimately improving clinical practice, will require identifying subgroups within the autism spectrum.
The biology of autism cannot yet be used diagnostically, and so—like most psychiatric conditions—autism is defined by behavior [Rett syndrome (Rett's disorder) is diagnosed by incorporating biology, but it has been moved out of the “Autism Spectrum Disorder" category in DSM-5]. The two international psychiatric classification systems (the Diagnostic and Statistical Manual of Mental Disorders [DSM] and the International Classification of Diseases [ICD]) remain useful for making clinical diagnoses, but each time these classification systems are revised, the new definitions inevitably subtly change the nature of how the conditions are construed. While acknowledging concerns about issues such as diagnostic inflation
New in DSM-5 is the explicit recognition of the “spectrum" nature of autism, subsuming and replacing the DSM-IV Pervasive Developmental Disorder (PDD) categorical subgroups of “autistic disorder," “Asperger's disorder," “pervasive developmental disorder not otherwise specified," and “childhood disintegrative disorder" into a single umbrella term “Autism Spectrum Disorder" (ASD). [Here and throughout we use the term “ASD" because this is what is used in DSM-5. However, in our publications over many years we have opted for the more neutral term “ASC" (Autism Spectrum Conditions) to signal that this is a biomedical diagnosis in which the individual needs support, and which leaves room for areas of strength as well as difficulty, without the somewhat negative overtones of the term “disorder," which implies something is “broken."] DSM-5 characterizes ASD in two behavioral domains (difficulties in social communication and social interaction, and unusually restricted, repetitive behaviors and interests) and is accompanied by a severity scale to capture the “spectrum" nature of ASD.
Also new in DSM-5, language development/level is treated as separate from ASD. This means an individual can have ASD
There have been concerns that the DSM-5 criteria may be more stringent than DSM-IV, such that some individuals who qualified for PDD will not meet the new ASD criteria. A series of studies testing the initial
In brief, these studies all show that DSM-5 provides better specificity (so reducing false-positive diagnoses), but at the expense of potentially reduced sensitivity, especially for older children, adolescents and adults, individuals without intellectual disability, and individuals who previously met criteria for diagnoses of DSM-IV “Asperger's disorder" or “pervasive developmental disorder not otherwise specified." It remains to be seen in real-life settings how diagnostic practice, service delivery, and prevalence estimates will be affected by applying DSM-5 ASD criteria. In particular, one major nosological issue is to what extent individuals fitting DSM-IV PDD but not DSM-5 ASD diagnoses will end up falling into the newly created diagnosis of “Social (Pragmatic) Communication Disorder"
Highlighting the dimensional nature of the two cardinal behavioral domains of ASD, as well as the improved organization of symptom descriptions, are excellent features of DSM-5. A unitary label of “ASD" accompanied by individualized assessment of needs for support will likely be useful in clinical settings, especially to guarantee the required levels of support for all individuals “on the spectrum" who will benefit from educational, occupational, social, mental health, and medical interventions (even if they are etiologically, developmentally, and clinically heterogeneous). However, this approach is not useful for research in general, given the known massive heterogeneity within such an omnibus label. Within autism there is a huge variability in terms of behavior (symptom severity and combination), cognition (the range of deficits and assets), and biological mechanisms. Acknowledging heterogeneity has led to the idea that there are many “autisms," with partially distinct etiologies, nested within the umbrella term of “ASD"
There are several meanings of the term “spectrum" in relation to autism. The differences are subtle but nontrivial. DSM-5 does not tease these apart, but in relation to future research into the “autism spectrum," it is important to be clear to which meaning the term “spectrum" refers.
“Spectrum" can refer to the dimensional nature of the cardinal features of autism
“Spectrum" can also refer to the
“Spectrum" can also refer to
DSM-5 holds back from listing subgroups by recommending the use of “specifiers" to record the severity of cardinal symptoms, current language and intellectual ability, onset age and pattern, and concurrent genetic/medical or environmental/acquired conditions
Category | Specifier | Example |
Pattern of atypical development | 1. Age and pattern of onset/regression | |
2. Trajectory of development | ||
3. Language onset | ||
4. Hyperlexia | ||
Biological sex | Male/female | |
Sex/gender-adjusted autistic features | Statistical characterization of autistic trait (e.g., percentile) relative to sex/gender-specific norms | |
Co-occurring condition | 1. Epilepsy | |
2. Macrocephaly | ||
3. Gastrointestinal disorders | ||
4. Immune disorders | ||
5. Hyperserotonemia | ||
6. Attention deficit/hyperactivity disorder | ||
7. Anxiety disorders | ||
8. Depressive disorders | ||
9. Tics/Gilles de la Tourette syndrome | ||
10. Obsessive-compulsive disorder | ||
11. Schizophrenia spectrum | ||
12. Dyslexia | ||
13. Personality disorders | ||
14. Self-injurious behaviors | ||
15. Sleep disruption | ||
16. Eating disorders | ||
17. Gender dysphoria | ||
Taxonomic formulation | 1. Asperger syndrome | |
2. “Aloof"/“passive"/“active but odd"/“loners" groups | ||
Motor abnormality | 1. Types of motor stereotypy | |
2. Coordination disorder | ||
3. Dyspraxia | ||
Intelligence | 1. IQ profile (including discrepancy among subtests) | |
2. Savant memory | ||
3. Savant spatial skills | ||
Current language (structural properties) | 1. Phonological/phonetic processing (including articulation) | |
2. Prosodic processing | ||
3. Morphological processing | ||
4. Syntactic processing | ||
5. Semantic processing | ||
6. Receptive vs. expressive abilities | ||
Social cognition | 1. Emotion perception and understanding | |
2. Face recognition | ||
3. Emotional contagion | ||
4. Social orienting | ||
5. Social and nonsocial reward processing | ||
6. Affective empathy | ||
7. Sympathy | ||
8. Joint attention | ||
9. Pretend play | ||
10. Theory of mind/mental perspective taking | ||
11. Self-referential cognition | ||
12. Alexithymia | ||
13. Metacognitive awareness | ||
Executive function | 1. Cognitive flexibility | |
2. Planning | ||
3. Inhibitory control | ||
4. Attention shifting | ||
5. Working memory | ||
6. Time perception | ||
Bottom-up perceptual processing | 1. Global-local perceptual processing | |
2. Low-level perceptual function and discrimination | ||
3. Synesthesia | ||
Top-down information processing | 1. “Central coherence" (global-local contextual processing) | |
2. “Systemizing" (drive to construct rule-based systems, ability to understand rule-based systems, knowledge of factual systems) | ||
Syndromic autism | 1. Fragile X syndrome | |
2. Rett syndrome | ||
3. Tuberous sclerosis complex | ||
4. Timothy syndrome | ||
5. Down syndrome | ||
6. Phenylketonuria | ||
7. CHARGE syndrome | ||
8. Angelman syndrome | ||
9. PTEN macrocephaly syndrome | ||
10. Joubert syndrome | ||
11. Landau-Kleffner syndrome | ||
12. Prader-Willi syndrome | ||
13. Smith-Lemli-Opitz syndrome | ||
14. Neurofibromatosis | ||
Familial aggregation | Simplex vs. multiplex | |
Gene-level variations | e.g., |
|
Copy number variations (CNVs) | (specify known ASD-association status, genetic loci, and deletion/duplication) | |
Social deprivation | Early social isolation or neglect* | |
*(specify timing: postnatal months X to Y) | ||
Environmental risk factor exposure | 1. Rubella virus infection during gestation* | |
2. Valproic acid exposure during gestation* | ||
3. Antidepressant exposure during gestation* | ||
*(specify timing: gestational weeks X to Y) |
It is notable that the US National Institute of Mental Health (NIMH) has initiated the Research Domain Criteria
DSM-5 ASD criteria should be commended for its clearer symptom descriptions and grouping, for acknowledging the spectrum nature of autism, and for recognizing the dynamic nature of development and how individuals interact with their environment. Moreover, for clinical purposes a unitary label of ASD may be beneficial in planning the support systems for
Toward this end, we have expanded the list of possible dimensional and categorical “specifiers" to improve our recognition of “the autisms." In addition, it is important to clarify the different definitions of the term “spectrum." Given that the spectrum extends into the general population, research needs to address the relationship between cardinal autistic symptoms and associated autistic traits (such as excellent attention to detail). Finally, we need to be fully aware of the inherent limitations of the existing psychiatric diagnostic systems, and consider other approaches that may be beneficial for research purposes
The practical implication of the arguments proposed in this article is that
Autism Spectrum Quotient
Autism Spectrum Conditions
Autism Spectrum Disorder
Autism Spectrum Screening Questionnaire
broader autism phenotype
Childhood Autism Spectrum Test
Diagnostic and Statistical Manual of Mental Disorders
International Classification of Diseases
US National Institute of Mental Health
Pervasive Developmental Disorder
Quantitative Checklist for Autism in Toddlers
Social Responsiveness Scale