5 conditions that have symptoms that overlap with Autism

The most recent prevalence rates for Autism Spectrum Disorder (ASD)sits at about 2.21% (Centers for Disease Control; CDC), with more males than females diagnosed with the condition (sorry my gender diverse friends, researchers are a bit behind on the data for gender nonconforming individuals). This estimate demonstrates a similar prevalence rate to Bipolar I Disorder and is double that of Schizophrenia and it pales in comparison to the rates for Major Depression (17%) and any anxiety disorder (19%), which would suggest that ASD is actually among the more rare mental health conditions.

Like many mental health disorders in recent years, people have begun self-diagnosing themselves using self-report surveys and comparing their experiences with others who have been diagnosed. Social media makes these sorts of comparisons more likely and much more prolific than in the past. If you've found yourself making such comparisons, you could have Autism, another diagnosis, or no diagnosis at all. Below are 5 conditions that are often considered during an Autism Assessment.

Reactive Attachment Disorder (or Trauma and/or Neglect during childhood)

One of the toughest conditions to differentiate from ASD is Reactive Attachment Disorder, as the symptoms can look identical. The sources of the symptoms tends to be the difference-maker. With RAD, symptoms commonly consist of impaired social skills, running from adults, tantrums, combative or aggressive behavior toward others, unusual behavior, and delayed developmental skills. The source of RAD symptoms are neglect and/or abuse during early childhood. Persistent delays in social and developmental skills as a result of abuse or neglect are well-documented. Studies of children from Romanian Orphanages, where children were abandoned after the Romanian government banned abortion and taxed people for being childless during the 60s, 70s and 80s, demonstrate the life-long impact of abuse and neglect. During the late 1980s and early 90s, research on the children housed in these over-populated, understaffed orphanages revealed that cognitive, social, and developmental delays could result directly from environmental conditions (e.g., being tied to beds, deprived of cognitive stimulation, little human contact). The effects of RAD last into adulthood, though the symptoms must be present prior to age 5. While it is possible for a person to have both RAD and ASD, the symptoms and early developmental history must be carefully delineated.

Social Anxiety Disorder

Social Anxiety Disorder is a condition that is marked by symptoms of extreme, paralyzing anxiety in social situations. The primary difference between ASD and SAD is the lack of developmental delays in ASD. Keeping in mind that ASD can be accurately predicted up to 90% off of the head-lag test at 3 months of age, individuals with SAD are unlikely to demonstrate an early developmental delay. The head-lag test is a simple test whereby a child is pulled up by their arms from laying on their back into a sitting position. If their head lags back, suggesting low muscle coordination or rigidity in the neck, it is indicative of a developmental delay. Early signs of SAD also exist and typically take the form of Selective Mutism Disorder, a diagnosis that applies to young children who have the capacity for speech, but lose their ability to talk under certain circumstances-- due to anxiety. The cornerstone of SAD is an impairing fear of being embarrassed, perceived as different, or concerns about being evaluated in a social setting. This can impair social-skills functioning, as a result of phobic-level anxiety, rather than a difficulty interpreting social cues. In fact, people with SAD are often hyper-aware of social cues and have a tendency to over-interpret. People with ASD can also have social anxiety; however, the sources of anxiety often has some distinct differences. Social anxiety in people with ASD has much more to do with over-stimulation and mental fatigue as a result of having to process, categorize, and make sense of memorized social cues and potential responses.

Schizoid Personality Disorder

I tend to think of the "personality disorders" as developmental disorders, resulting from person-environment interactions, as there is good evidence that personality is the result of genetic and environmental factors. See the research by Neuroscientist James Fallon for more about the nature-nurture interaction that underlies Antisocial Personality Disorder. Schizoid Personality Disorder (SPD) is one of the 12 personality disorders, which is not typically diagnosed until late adolescence/ early adulthood, presumably because personality does not fully develop until that time. SPD is marked by difficulty in social relationships, primarily a lack of desire for social connections, as opposed to an inability to understand social skills or difficulty functioning in social situations. It is a rather common misconception that people with ASD do not have an interest in social connections-- the alternative is actually more often the case. Many people with ASD desperately desire close social connections, but often lack the skills to initiate or maintain those connections. People with SPD, on the other hand, are not interested in social connection. Other symptoms of SPD include choosing solitary activities over those involving others, little interest in sexual activity with another person, enjoys few interests or activities, and has few connections outside of immediate family. Additionally, people with SPD tend to demonstrate few emotions and are not affected by the praise or criticism of others. This emotional under-reactivity is often called emotional flatness or flattened affect. People with SPD often do not have the developmental delays that people with ASD experience early in their developmental history (i.e., delays in walking, talking, crawling, joint-attention, non-response to name, unusual use of language, unusual interests or patterns of play, stereotyped or repetitive behaviors, etc.). Interestingly, ASD and the schizophrenia family of conditions have been compared and contrasted for decades. The primary noted difference is the presence of hallucinations and thought disturbance with schizophrenia, symptoms that don't exist with Schizoid Personality Disorder, making the differentiation from ASD more nuanced.

Attention Deficit Hyperactivity Disorder

While ADHD requires little introduction for most people, it is important to noted that ADHD is a developmental disorder, like ASD. ADHD is marked by symptoms of inattention and impulsivity that are thought to be the result of a lower functioning frontal lobe. The skills most affected by ADHD are referred to as "executive functioning" skills and include things like planning ahead, inhibiting behaviors, managing emotions, motivation, initiating tasks, and sustaining attention. When you think about the number of executive functioning skills that are used in social situations, it makes sense that people with ADHD also struggle with social situations. People with ADHD and ASD may both have a tendency to "blurt out" responses and comments or act impulsively, though they derive from different sources. With ADHD, the behavior is likely the result of an under-stimulated frontal lobe. With ASD, those same behaviors are more likely the result of delayed learning of social skills due to overstimulation (i.e., due to less pruning of neurons) and a lower density of neurons in the areas of the brain responsible for coordination and movement (i.e., corpus callosum and cerebellum). It is also possible that there are shared neurological mechanisms that have not been entirely elucidated. An additional feature of ADHD, called hyperfocus, can be confused with symptoms of ASD (i.e., narrow interests or perseverative focus). The difference tends to be on the uniqueness or narrowness of the stimulus. For example, children with ASD may display a narrow focus for one video or part of a video played on repeat for hours at a time, they may focus in on a part of a toy (e.g. a wheel that they spin endlessly), and they may display attention that is out of proportion to what is needed in the moment (e.g., staring at a ceiling fan and not responding to their name when called). Video games and TV are common hyperfocus moments for children with ADHD and while they may hyperfocus, their attention is absorbed into a variety of competing stimuli. Notably, many children with ADHD outgrow the condition (or learn to manage the symptoms more effectively) by adulthood, while ASD is thought to have a lifelong trajectory.

High Intelligence

While high intelligence is not a diagnosis, perhaps it should be. Intellectual developmental disorder is a diagnosable DSM-5-TR condition, marked by lower cognitive capacity that affects a person's ability to manage daily tasks and is often accompanied by an IQ of 70 or less-- though there is no official cut-off score since the DSM-5 was published in 2013. On the other end of the cognitive ability spectrum, high intelligence (cognitive capacity 2 standard deviations above average or a standard score of 130 or above), has been more recently identified as a form of neurodivergence. The overlap of ASD and high intelligence has also been the subject of research. Common neurological underpinnings of both ASD and high intelligence include larger brains than average. Since ASD occurs in individuals with lower cognitive ability as well, it is difficult to draw any conclusions, however. One notable difference may be that high intelligence has been associated by richer dendritic connections (i.e., the branch-like connections of neurons) and ASD has been associated by impaired pruning of neurons during the early developmental period (i.e., humans typically lose the most neurons in their life between birth and age 2). Perhaps the shared large brains are from two similar, yet different mechanisms that have slightly different outcomes (i.e., enhanced sensory processing vs sensory overstimulation). People with high intelligence may have difficulty with social situations or skills as a result of a willingness to question social conventions, boredom, annoyance, anxiety, or as a result of connecting data-points that others do not. They may also develop unique and/or precocious interests and abilities (e.g., a well-labeled rock collection by age 7), though this is qualitatively different than the narrow, perseverative interests often seen in ASD. People who have high intelligence without ASD do not demonstrate the developmental delays found in individuals with ASD (e.g., delays in walking, talking, sitting up, unusual focus on specific objects, shapes, or movements, sensory intolerance, repetitive movements, etc.). Alternatively, people with high intelligence alone typically meet their developmental milestones early. Keep in mind that ASD is categorized as a neurodevelopmental disorder and that these early developmental symptoms are cornerstones of diagnosis.

Additional Consideration

The aforementioned conditions do not represent an exhaustive list of differential diagnoses for ASD, but they do represent reasonable alternatives to the diagnosis. It is important to note (and a subject for another blog) that many symptom inventories for ASD include symptoms that overlap many other diagnoses, including those discussed above. A well-qualified clinician can help to more definitively diagnose ASD, though it should be undertaken with some caution. Not all clinicians are trained to administer psychological tests and perform integrative assessments and it is essential to work with someone who has the appropriate training. ASD is not a one-sized-fits all condition and the nuances of the diagnostic process are many. If you are someone who has convinced yourself that ASD is the diagnosis that fits best for you, I hope that you would consider the broad range of neurodivergence that does not fall into any diagnostic category. Creative, eccentric, intelligent people are a part of the human diversity in cognitive functioning. Assuming a diagnosis when you haven't been properly evaluated by a qualified mental health professional is strongly discouraged. It can create confusion, emotional pain and frustration for people who have been diagnosed, as people inevitably compare themselves to others.

Davidson, C., O'Hare, A., Mactaggart, F., Green, J., Young, D., Gillberg, C., & Minnis, H. (2015). Social relationship difficulties in autism and reactive attachment disorder: Improving diagnostic validity through structured assessment. Research in developmental disabilities, 40, 63–72. https://doi.org/10.1016/j.ridd.2015.01.007

Martos-Perez, J., Freire-Prudencio, S., Llorente-Comi, M., Ayuda-Pascual, R., & Gonzalez-Navarro, A. (2018). Autismo y cociente intelectual: estabilidad? [Autism and intelligence quotient: stability?]. Revista de neurologia, 66(S01), S39–S44.

Mottron, L., & Bzdok, D. (2020). Autism spectrum heterogeneity: fact or artifact?. Molecular psychiatry, 25(12), 3178–3185. https://doi.org/10.1038/s41380-020-0748-y

Cumin, J., Pelaez, S., & Mottron, L. (2022). Positive and differential diagnosis of autism in verbal women of typical intelligence: A Delphi study. Autism : the international journal of research and practice, 26(5), 1153–1164. https://doi.org/10.1177/13623613211042719

Centers for Disease Control. Accessed 2/7/2023. https://www.cdc.gov/ncbddd/autism/features/adults-living-with-autism-spectrum-disorder.html

Weir, K. (2014). The lasting impact of neglect. APA Monitor. https://www.apa.org/monitor/2014/06/neglect

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). https://doi.org/10.1176/appi.books.9780890425787

Underwood, J. F., DelPozo-Banos, M., Frizzati, A., John, A., & Hall, J. (2022). Evidence of increasing recorded diagnosis of autism spectrum disorders in Wales, UK: An e-cohort study. Autism, 26(6), 1499–1508. https://doi.org/10.1177/13623613211059674

National Public Radio (2013). Uncovering the Brain of a Psychopath. https://www.npr.org/2013/10/25/240751585/uncovering-the-brain-of-a-psychopath

Hommer, R. E., & Swedo, S. E. (2015). Schizophrenia and autism-related disorders. Schizophrenia bulletin, 41(2), 313–314. https://doi.org/10.1093/schbul/sbu188

** DISCLAIMER: The information in this blog is informative only and is limited to the experience, knowledge and opinions of the author. The content should be read with caution and individuals are responsible for doing their own research and speaking with relevant professionals (e.g., legal, mental health, medical, insurance plan, educator, etc.) before making any decisions based on the information read here. Use at your own risk. The information in this blog is not a substitute for consultation with relevant professionals (e.g., legal, mental health, medical, insurance plan, educator, etc.). The author, entity, and/or poster of this content is not responsible for its use.**