The “Undiagnosed” Autism Spectrum Disorder: Need for Support in Adolescence to Prevent Secondary Disorders in Adulthood

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by difficulties in social interaction and communication, repetitive behaviors, and narrow interests. Disease units classified by categories are not clearly demarcated as “Normal” or “Abnormal” and are often distributed as a spectrum without boundaries. As indicated by the word “Spectrum” in ASD, there is a continuous link between individuals with clear symptoms and significant autistic tendencies and those with typical symptoms that are not clear and have typical development [1]. Symptoms of developmental disorders occur in their purest form during childhood. However, after adolescence, they are more difficult to recognize because of interactions with their surroundings and modifications by the individual. While a diagnosis of developmental disability requires that signs of the disorder have been present since childhood, information about childhood is often inadequate in adult cases. Diagnosis is deemed practically impossible because of the lack of information regarding childhood [2]. Particularly in cases of individuals with average intelligence levels, it is difficult to link parental awareness with medical examination behaviors [3].

People with an “Undiagnosed” ASD can exhibit several patterns. In one pattern, a person with ASD is overlooked until adulthood and is only suspected of having a developmental disorder when he or she begins to have social difficulties in school and work life and shows symptoms of adjustment disorders and depression. Rynkiewicz et al. [4] found this pattern was observed more frequently among women with average or above-average intelligence and conversational fluency. These women were less likely to represent the diagnostic stereotypes of autism and more likely to be camouflaged [5]. Adolescents with this pattern are more likely to develop medical problems such as anxiety disorders, depression, and eating disorders, indicating a need for early support [6]. The second pattern is indicated as the Broader Autism Phenotype (BAP). The BAP refers to characteristics that do not meet the diagnostic criteria for ASD in terms of social, cognitive, or personality traits but possess broad ASD characteristics and is the central theme in studies of parents, siblings, or twins of children diagnosed with autism. Research focusing on the genetic mechanisms of ASD and environmental factors has shown that in families where two or more children are diagnosed with ASD, other siblings exhibit more pronounced BAP traits [7]. However, regarding BAP, research findings have been inconsistent, with some studies showing that the majority of siblings of individuals with ASD have more typical development and do not exhibit autistic traits when compared to related controls. Thus, an overview of BAP research shows that the focus has been on exploring the characteristics of genetic determinants among individuals with ASD in infancy and their parents (i.e., parents, children, twins, and siblings) and on family and sibling support [8-10].

In Japan, the Law for the elimination of discrimination against persons with disabilities came into effect in 2016 and required governments, schools, and companies to provide necessary and reasonable accommodation for the removal of social barriers as much as possible and to prevent the infringement on the rights and interests of persons with disabilities, including developmental disabilities. However, some teachers in Japanese schools believe that if ASD is not diagnosed, there is no need to give consideration. Because ASD is a spectrum, it is highly likely that students with ASD characteristics who have not been diagnosed will be left without the support they need. People with significant ASD traits have a history of strained relationships due to miscommunication, attention to detail, and an inability to cope with sudden changes in circumstances [2]. Consequently, they accumulate trauma with age and are exposed to mental illnesses as secondary disorders. Even if a psychiatrist examines the patient, the symptoms and course of the disease tend to be atypical, and the underlying developmental disorder is unlikely to be detected. Such cases are difficult to treat, and typical treatments for depression do not cure them or even worsen their condition soon after they improve [11].

Regardless of an individual’s diagnostic status, a society in which people with significant ASD characteristics can live comfortably would contribute to a more inclusive place for everyone. It is assumed that a certain number of school students have significant characteristics of undiagnosed ASD. Even in cases where the diagnosis is overlooked in childhood, it is necessary to promote understanding among teachers and establish an environment and system to provide appropriate support in school life during the sensitive middle and high school years.

This study was supported by the JSPS KAKENHI [Grant numbers: 20K10878 and 21K11077].

1. Kamio Y, Inada N, Moriwaki A, Kuroda M, Koyama T, et al. (2013) Quantitative autistic traits ascertained in a national survey of 22,529 Japanese school children. Acta Psychiatr Scand 128(1): 45-53.
2. Murakami S (2023) Characteristics of adult developmental disabilities and “gray zone” and points of support. The Japanese Journal for Public Health Nurse 79(1): 12-17.
3. Inokuchi E, Kamio Y (2013) Qualitative analyses of verbal fluency in adolescents and young adults with high-functioning autism spectrum disorder. Res Autism Spectr Disord 7(11): 1403-1410.
4. Rynkiewicz A, Kozik MJ, Slopien A (2019) Girls and women with autism. Psychiatr Pol 53(4): 737-752.
5. Bargiela S, Steward R, Mandy W (2016) The experiences of late-diagnosed women with autism spectrum conditions: An investigation of the female autism phenotype. J Autism Dev Disord 46(10): 3281-3294.
6. Belcher HL, Zamir SM, Stagg SD, Ford RM (2023) Shining a light on a hidden population: Social functioning and mental health in women reporting autistic traits but lacking diagnosis. J Autism Dev Disord 53(8): 3118-3132.
7. Pisula E, Sadowska KZ (2015) Broader autism phenotype in siblings of children with ASD: A Review. Int J Mol Sci 16(6): 13217-13258.
8. Bishop DVM, Maybery M, Wong D, Maley A, Hallmayer J (2006) Characteristics of the broader phenotype in autism: A study of siblings using the children’s communication checklist-2. Am J Med Genet B: Neuropsychiatr Genet 141(2): 117-122.
9. Rankin JA, Tomeny TS (2019) Screening of broader autism phenotype symptoms in siblings: Support for a distinct model of symptomatology. J Autism Dev Disord 49(11): 4686-4690.
10. Tsai HWJ, Cebula K, Watson SF (2017) The role of the broader autism phenotype and environmental stressors in the adjustment of siblings of children with autism spectrum disorders in Taiwan and the United Kingdom. J Autism Dev Disord 47(8): 2363-2377.
11. Kamio Y, Inada N, Koyama T (2013) A nationwide survey on quality of life and associated factors of adults with high-functioning autism spectrum disorders. Autism 17(1): 15-26.