Autism according to diagnostic and statistical manual of mental disorders 5(th) edition: The need for further improvements.

The fifth edition of the diagnostic and statistical manual of mental disorders (DSM-5) introduced significant changes in the classification of autism spectrum disorders (ASD), including the abolition of the diagnostic subcategories proposed by DSM-IV-Text Revision. DSM-5 describes three levels of increasing severity of ASD. The authors report two explanatory cases with ASD (verbal boys, aged about 7 and a half years, without intellectual disability). According to DSM-5, both cases fall into the lowest severity level of ASD. However, their neuropsychological and neurobehavioral profile varies significantly. While the first boy showed a prevalent impairment of visuoconstructional and visuoperceptual abilities, the second one presented a predominant involvement of verbal functions, with qualitative impairments in communication. A further step forward in the definition and classification of ASD, taking into account both intensity and quality of symptoms, is recommended in order to formulate a reliable prognosis, plan an individualized treatment and monitor the clinical course over time.

Introduction

Autism spectrum disorders (ASD) are lifelong conditions severely impairing social skills and autonomy. According to the fifth edition of the diagnostic and statistical manual of mental disorders (DSM-5),[1] ASD core features are: Persisting deficits of social communication and interaction; restricted and repetitive behaviors, interests, activities. Compared to the previous edition (DSM-IV-Text Revision),[2] DSM-5 introduced significant changes. In the diagnostic criteria, language abilities not employed in social communication have been de-emphasized. Further, the diagnostic subcategories, that is, autistic disorder, Asperger disorder, Rett disorder, childhood disintegrative disorder, and pervasive developmental disorder (PDD) not otherwise specified, have been abolished. DSM-5 describes three levels of increasing severity of ASD, from (1) (“requiring support”) to (2) (“requiring substantial support”), finally to (3) (“requiring very substantial support”).[1]

We report two explanatory cases affected by ASD with the same severity level, according to DSM-5, but with remarkable differences regarding the neuropsychological and neurobehavioral profile.

Case Reports

Case 1

Male, aged 7 years 5 months. Family history was positive for schizophrenia in a maternal great-grandmother. The maternal grandfather was a very skilled electronics technician, but he lacked empathy and had difficulties relating to others; as a child, he self-taught himself four languages.

The boy was born at full term; pregnancy and delivery were uncomplicated, psychomotor development was normal. Since 18 months of age he appeared isolated, wanted things to be placed in a certain order, played along with water and looked at books for hours. He began to read letters and numbers at 20 months. His language was polished and characterized by some neologisms. He made nasty comments aloud in the presence of concerned persons. His face expressions were very serious. Understanding of others’ feelings based on facial expressions was lacking. Eye contact was inconstant. Unusual interests for sinks, toilets, pipes, switches, lights were present. The boy was very afraid that the bulbs could explode. His behavior was often oppositional and hyperactive. He showed great ability to design projects, e.g., a new home or railway line and was frustrated by not being able to get the highest grade in maths. Applied behavior analysis (ABA) intervention was conducted. At school, he had a special needs teacher. Neurological examination was normal.

Neuropsychological and neurobehavioral assessment

Wechsler Intelligence Scale for Children-III Edition (WISC-III) showed a full intelligence quotient (IQ) =102, with a significant discrepancy (P < 0.01) between verbal IQ (=115) and performance IQ (=89). Comparing the 10 WISC-III subtests among them [Table 1], the score in vocabulary, involving lexical knowledge, prevailed significantly (P < 0.01), while the scores in block design (visuoperceptual abilities, visuomotor coordination) and in object assembly (visual analysis, construction of objects) were significantly lower (P < 0.01). Copy of Rey–Osterrieth complex figure, involving visuoconstructional and visuospatial abilities, was unrecognizable. He had a poor performance in a test for motor praxis ability included in “BVN 5–11” (Italian battery of neuropsychological assessment for children and adolescents). Autism diagnostic observation schedule (ADOS) (module 3) showed a score above the cut-off for autism spectrum in language and communication and above the cut-off for autism in reciprocal social interaction; the overall result was above the cut-off for autism. Childhood autism rating scale second edition-high functioning (CARS2-HF) showed the presence of mild to moderate ASD symptoms. Krug Asperger's disorder index (KADI) appeared compatible with a highly probable Asperger's disorder diagnosis; among the findings from this questionnaire the following should be noted: Demanding a lot from himself and from others; too serious appearance; fluent language and adequate vocabulary before 5 years of age; tendency to say embarrassing things to others; unusual way to enact or talk about fantasies or thoughts.

Table 1

Standardized scores obtained by Case 1 and 2 in WISC-III subtests. The first five from the left are the verbal subtests, the other five are the performance subtests

According to DSM-5 criteria, this case had an ASD diagnosis with severity level 1.

Case 2

Male, aged 7 years 5 months. Family history was positive for: Learning disorder in the older sister, ASD in the younger brother. During pregnancy, threatened abortions treated pharmacologically occurred. He was born at 37 weeks of gestation by induced labor due to preeclampsia. Apgar scores were normal. Psychomotor development was normal except for language as the child began to speak sentences with a slight delay. He was very attracted by numbers and puzzles. Hypersensitivity to visual, auditory and tactile stimuli was present. Already from kindergarten he appeared isolated both at home and school. He had intolerance for what was new and frustrations. His behavior was often hyperactive and attention was lacking. Imagination seemed rather poor, with the need for scientific explanations for everything. Spontaneous play appeared limited to some materials and rather schematic. He liked to collect stones from the sea. The boy tended to verbally interact with others without looking at them. Social-emotional reciprocity was lacking: He often followed the course of his thoughts and conversational exchanges remained limited. Comprehension of verbal messages tended to be literal, leading to difficulties in understanding the meaning of metaphors, jokes, and slang expressions. Language was fluent even if sentences were often incomplete. Prosody was slightly mechanical. Neologisms were present. Narration of event sequences was hard for him. First speech therapy and psychomotricity were conducted, then ABA intervention. At school, he had the special needs teacher. Neurological examination was normal.

WISC-III showed a full IQ = 95, with a verbal IQ = 88 and a performance IQ = 104: This difference was significant at 0.05 level, very near to 0.01 level. Comparing the 10 WISC-III subtests among them [Table 1], the score in comprehension, involving social and practical judgment, was significantly lower (P < 0.05), while the score in picture completion, involving visual analysis and attention to detail, was almost significantly higher (P = 0.05). The developmental test of visual-motor integration was normal. He had a normal performance in a test for motor praxis ability included in “BVN 5–11”. ADOS (module 3) showed a result above the cut-off for autism both in language and communication, and in reciprocal social interaction; consequently also the overall result was above the cut-off for autism. CARS2-HF showed the presence of mild to moderate symptoms of ASD. KADI was compatible with an extremely low probability of Asperger's disorder diagnosis.

According to DSM-5 criteria, this case had an ASD diagnosis with severity level 1.

Discussion

The description of these two explanatory cases underlines some critical points of the current setting of DSM-5 classification for ASD. According to DSM-5 criteria, both cases fall under ASD, due to a significant impairment in social communication and interaction, and to restricted interests and activities. At the same time, both cases (verbal boys, aged about 7 and a half years, without intellectual disability), based on DSM-5 description, fall into the lowest severity level of ASD (level 1), which by definition requires support. However, their respective neuropsychological and neurobehavioral profiles were notably different. While the first boy showed a prevalent impairment of visuoconstructional and visuoperceptual abilities, with language functions even overdeveloped in some respects, the second boy presented an almost specular profile characterized by a predominant involvement of verbal functions, with qualitative impairments in communication, and a preservation of nonverbal functions, some of which (particularly visual analysis) were the strength of his development. These differences have been objectified by standardized assessment tools.

Admittedly, a detailed neuropsychological and neurobehavioral profile represents a basic prerequisite for the treatment of patients with ASD. In the past years, when the DSM-IV-Text Revision (TR) was being used, among the PDDs, Asperger disorder, together with autistic disorder, has been the most studied from the neuropsychological and neurobehavioral perspective.[34567] Basically, according to DSM-IV-TR criteria, the main distinguishing features that characterized Asperger disorder compared with other PDDs, were the absence of intellectual disability and the presence of structured language. Further, we could observe a cognitive profile characterized by strengths in verbal skills (e.g., vocabulary) and weakness in nonverbal skills (e.g., visuospatial and visuomotor abilities). Finally, relatively mild clumsiness and motor difficulties could be associated.[2] In the past, several papers highlighted the differences between neuropsychological profiles of Asperger disorder and “high-functioning” autistic disorder,[345] but over the years the opinion of the authors that devalue these differences has prevailed.[67] According to DSM-IV-TR criteria,[2] both cases fall into PDDs; nevertheless, while the first boy would receive a diagnosis of Asperger disorder, the second one, due to his qualitative impairments in communication, would rather receive a diagnosis of autistic disorder, to be considered “high-functioning”. One of DSM-5 assumptions is the lack of data supporting the distinction between these two entities,[89] but, unfortunately, the current DSM approach (three severity levels) does not allow the division of patients with autism into sufficiently homogeneous groups. The description of these two cases is indicative of this lack. Our report is not meant to suggest a return to the past, but rather to give a cue to improve the current DSM classification. We believe that a further step forward in ASD definition and classification is necessary in order to meet the needs of affected individuals from the rehabilitation perspective. In our view it is important to take into account not only the intensity of symptoms, but also their quality, in order to formulate a reliable prognosis, plan an individualized treatment, and monitor the clinical course over time. In addition, description of detailed behavioral phenotypes, allowing the creation of homogeneous subgroups of patients with ASD, may be useful also for genetic research.