Autism in Adults: Symptoms, Signs and Traits

• OVERVIEW
• SYMPTOMS
• ADULTS
• CHILDREN
• WOMEN
• DIAGNOSIS
• TREATMENT
• MEDICATION

In England, about 1 in every 100 adults (0.9%) is recorded as autistic, although community findings and adult autism diagnosis data suggest the true number is likely higher because many remain undiagnosed.

In our clinical work at AuDHD Psychiatry, where we support neurodivergent individuals and their families, we often see how autism traits may only become clearer later in life. Many adults reach this point without a prior diagnosis, and a structured assessment can provide a clearer way to understand whether these traits align with adult autism.

For many, learning about autism allows long-standing challenges to be reframed not as personal shortcomings, but as patterns that can be understood, managed, and supported with appropriate clinical and lifestyle interventions.

Key Takeaways

• Data suggest one in every 100 adults has autism, but it’s likely higher than that.
• Autism in adults is likely underdiagnosed; it is more common than the numbers suggest.
• The core symptoms of autism in adults are the same as the symptoms of autism in children, but they may manifest more subtly or in different ways.
• Autism leads to pervasive communication and interaction difficulties and restricted, repetitive patterns of behaviour, interests or activities.
• Autism is a neurodevelopmental condition, so an autism diagnosis requires the presence of autistic traits during the early developmental years.

What Are the Common Symptoms of Autism in Adults?

Autism is a neurodevelopmental condition. An autistic person’s brain is structurally and functionally different from a typical, non-autistic brain.

Due to their atypical or neurodivergent brain, adults with autism spectrum disorder (ASD) perceive the world in a unique way. Consequently, those with adult autism may:

• Be unable to read social cues
• Find social rules difficult to understand
• Find it hard to gauge other people’s thoughts and feelings
• Cannot easily express their own thoughts and feelings
• Process sensory information differently

All these give rise to autism symptoms, particularly the following autistic traits in adults:

• Social anxiety and difficulty making friends
• A preference for their own company
• A tendency to be literal (which is why using idioms is not a good idea when speaking to someone with autism)
• A need for a set, unchanging, and predictable routine
• A need for strict planning and detailed plans
• Excessive bluntness in speech
• A total absence of facial expression
• A tendency to commit socially inappropriate actions

The last item, in particular, can make other people think an autistic adult is rude or uninterested. It can lead to the following ‘social mistakes’ that can indicate signs of autism in adults:

• talking over people
• avoiding eye contact
• talking too loudly 
• getting unduly upset with an accidental touch or someone’s proximity
• An intense interest in or dislike for certain things

Autistic individuals can become intensely interested in a particular object (e.g., leaves) or activity (finding square patterns). They may dislike the feel of clothing tags against their skin or be highly bothered by the sound of chewing.

These tendencies are fueled by their hypersensitivity or hyposensitivity to sensory information. Thus, someone with autism may be able to detect subtle patterns, register the littlest details, and detect the most nebulous sound or smell.

Note: Autism has three levels: 1, 2 and 3. The higher the number, the more severe the condition and the more support needed. Thus, level 1 autism is milder than level 2 autism, while level 3 autism is the most severe and requires the most autism support.

How Does Autism Show Differently in Adults?

Autism typically manifests differently in adults than it does in children. Over time, someone with autism may learn to mask their symptoms and mimic desirable social behaviours. These strategies help individuals with autism fit in and get along better with others.

Thus, an autistic adult may be able to make eye contact, smile back, laugh at jokes, or choose their words more carefully. They may become adept at hiding their reactions to sensory stimuli that annoy them.

The autistic traits in adults remain. They just become more subtle or obscure as adults become more adept at masking their symptoms.

Note: Masking, camouflaging and mimicking are more commonly associated with autism in women than in men. This is why the signs of autism in adult men may be more noticeable than they are in women and why NHS England’s data indicate autism in adults is 7.5 times more prevalent among males than females. 

In contrast, children with autism have yet to learn social coping mechanisms. The signs of autism in children, thus, tend to be more detectable and obvious.

Unfortunately, constant camouflaging is mentally exhausting and can lead to autistic burnout without timely support and autism treatment. This is why early and timely diagnosis is crucial.

That said, adult autism intervention is possible and available, and it can have a significant impact on an autistic adult’s quality of life. Thus, if you think you may have adult autism, seek a diagnosis as soon as you can. Ask your GP for an NHK assessment referral or get the much faster private autism assessment.

What Are the Diagnostic Criteria for Autism in Adults?

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) outlines the diagnostic criteria for autism. The same criteria are used to diagnose autism in children and adults, and they say the two primary indicators of autism are:

1. Persistent and pervasive difficulties in communicating and interacting in multiple social contexts, which manifest (or have manifested) as a deficit in all of the following:

• Social-emotional reciprocity (e.g., inability to initiate or reciprocate conversations, interests, and emotions)
• Nonverbal communicative behaviours (e.g., inability to make eye contact, awkward gestures, lack of facial expressions)
• Developing, maintaining, and understanding relationships (e.g., inability to make friends, lack of interest in others, difficulty adjusting behaviour to social context)

2. Restricted and/or repetitive patterns of behaviour, interests, or activities, which manifest (or have manifested) as any two of the following:

• Repetitive or stereotypical motor movements, use of objects, or speech (e.g., repeating words or phrases spoken by others, obsessively arranging objects in a straight line, repeated rocking on one’s heels)
• An intractable insistence on sameness, a rigid adherence to routines, or a ritualistic pattern of verbal or nonverbal behaviour (e.g., a loathing for changes in usual routes, bathing at exactly the same time every day)
• Extremely restricted, fixated interests that are abnormally intense or focused (e.g., an atypical interest in pen tips)
• Extremely high or low reactivity to sensory input or an unusual interest in sensory aspects of the environment (e.g., abnormal response to pain or temperature, an excessive need to smell or feel things)

Additionally, for an autism diagnosis to be made, the symptoms:

• Must have been present in the early years, although they might not have fully manifested or might have been masked
• Must cause clinically significant impairment in one or more functional areas (e.g., social, occupational)
• Cannot be better explained by an alternative condition, such as an intellectual disability or a developmental delay.

Can Autism Be Diagnosed in Adulthood?

Yes, autism can be diagnosed in adulthood. However, there is no adult-onset autism.  Autism is a neurodevelopmental disorder, so it is present since birth.

In other words, an autism diagnosis in adulthood doesn’t mean autism developed in adulthood. It only means the early manifestations of autism were missed or not detected, which is why autism couldn’t be diagnosed sooner.

Thus, the DSM-5-TR criteria for autism diagnosis require the presence of autistic traits and symptoms in childhood before adult autism can be determined.

How Is Autism Treated in Adults?

There are several ways to treat autism in adults. These treatment methods are designed to help autistic adults manage their symptoms, thereby reducing functional impairment in social, occupational, and other areas.

Treatment Category	Treatment Focus	Treatment Approach	Popular Strategies
Behavioural	Changing behaviours	Analyses what happens before and after a particular behaviour and  inculcates behavioural change through training	Applied behaviour analysis (ABA)
Developmental	Developing functional skills	Equips autistic adults with functional skills (e.g., communication, life skills, gross and fine motor movements)	Occupational and functional therapy:  Physical therapy Speech and language therapy
Social-Relational	Building relationships Improving social skills	Introduces social and relational exercises and activities to encourage social bonding	Developmental, individual differences, relationship-based (DIR) floortime for adults Program for the education and enrichment of relational skills (PEERS) Structured social skills groups
Psychological	Coping with mental health issues Changing perspectives, thoughts, and feelings that may be causing problematic behaviour	Encourages narration and sharing to expose links between thoughts, feelings, and behaviours	Cognitive behaviour therapy
Pharmacological	Improving functioning and preventing self-harming behaviour	Prescribes medication to manage the symptoms of conditions co-occurring with autism	*There’s no medication for autism, but the following may be prescribed to manage co-occurring conditions: Antipsychotics Serotonin reuptake inhibitors (SSRIs) Stimulants
Alternative			Special diets (gluten-free, omega-rich, whole foods diet) Herbal supplements Mindfulness exercises Relaxation exercises Strength training Arts therapy Animal therapy

Frequently Asked Questions on Autism in Adults

Do You Have Adult Autism?

The true prevalence of autism in adults is believed to be the same as its prevalence among children. Even so, autism is diagnosed more often in children than in adults.

This may be because some autistic adults do not know they have autism. It may also be because of some who, despite believing they have autism (reinforced by a positive autism test result), would not get an assessment for confirmation. NHS England data reveal that only around 35% of adults who think they’re autistic obtain a professional autism diagnosis.

If you think you have autism, get assessed. Adult autism must be addressed and diagnosed. Only then can you get workplace or university accommodations and obtain the support you need to thrive and live a better life.

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