ADHD, Autism and Mental Health: Understanding Overlap and Complexity

In clinical practice, ADHD and autism rarely present in isolation. Many adults seeking assessment describe difficulties with emotional regulation, anxiety, low mood, sleep disturbance or burnout. These experiences are often interconnected, and understanding how they relate to one another is a central part of good assessment.

There is increasing recognition within psychiatry that neurodevelopmental differences are central to understanding many mental health presentations. A recent paper in the British Journal of Psychiatry described neurodivergence as “the elephant in the room” in psychiatry, highlighting the extent to which it remains under-recognised in routine clinical practice.

The distinction between neurodevelopmental conditions and mental illness is sometimes presented as clear-cut. In reality, it is anything but and the relationship is more complex.

Overlap is the rule, not the exception

Research consistently shows that ADHD and autism are associated with higher rates of mental health difficulties, including anxiety, depression, trauma-related symptoms and sleep disturbance.

Some symptoms overlap directly. For example, impaired concentration may occur in both ADHD and depression. Social withdrawal may be seen in autism, anxiety, or low mood.

In addition, living with unrecognised neurodevelopmental differences can itself contribute to psychological distress over time.

A common presentation is someone who has been treated for anxiety for many years, with only partial improvement, and begins to wonder whether something else might also be contributing.

The risk of misattribution

One of the central challenges in assessment is determining what is driving a person’s difficulties.

For example:

• Is emotional dysregulation a feature of ADHD, or related to trauma?

• Is social difficulty best explained by autism, anxiety, or both?

• Is poor concentration due to ADHD, depression, sleep disturbance, or physical health factors?

  
  

Without careful assessment, there is a risk of focusing on one explanation while overlooking others.

It is not uncommon to meet individuals who have received several different diagnoses over time, each capturing part of the picture, but none fully explaining their experience.

Diagnostic overshadowing

Diagnostic overshadowing can occur in both directions:

• Neurodevelopmental conditions may be missed when symptoms are attributed solely to mental illness

• Mental health difficulties may be minimised when everything is explained in terms of ADHD or autism

  
  

Both patterns are seen in practice and can lead to incomplete or ineffective treatment.

When disentangling is particularly difficult

In some groups, the interface between neurodevelopmental differences and mental health is especially complex.

This includes:

• women, particularly those who have masked or compensated over many years

• individuals from minoritised backgrounds

• people for whom detailed early developmental information is not available

  
  

In these situations, clinicians may not have a clear developmental history to draw on, and presentations may reflect years of adaptation, misdiagnosis or unmet need.

For example, a woman presenting in midlife with burnout, anxiety and cognitive difficulties may be experiencing the combined effects of long-standing ADHD, chronic stress and hormonal change.

This makes it essential to take a longitudinal and nuanced approach, rather than relying on a single explanation.

How we approach assessment at Effra Clinic

In the Effra Clinic, assessment is designed to reflect this complexity. All of our assessments are psychiatrist-led, which is particularly important when neurodevelopmental differences and mental health conditions overlap as psychiatric training is centred on the assessment and diagnosis of mental illness, including the ability to distinguish between emotional distress, psychiatric disorders, neurodevelopmental conditions and physical health contributors.

This breadth of experience is essential when presentations are not straightforward. Without this level of assessment, there is a risk that important aspects of a person’s experience are either overlooked or over-attributed to a single diagnosis.

In practice, careful assessment also requires time. Many of the difficulties people describe are nuanced and, at times, difficult to talk about. Developing a clear understanding depends on allowing space for these experiences to be explored, and for rapport to develop so that people feel able to discuss areas that may have been hard to talk about previously.

Assessment is also collaborative. It is common for more than one member of our clinical team to be involved, bringing different perspectives and areas of expertise.

The aim is to develop a coherent formulation, rather than a single-label explanation.

Managing the overlap: neurodevelopment and mental health

Understanding the relationship between ADHD, autism and mental illness is only the first step. Equally important is how these difficulties are managed in practice.

Where both are present, treatment needs to take account of both neurodevelopmental differences and mental health needs.

For example, someone with ADHD and significant mood disorder may benefit from both ADHD medication and management of their mood, rather than either in isolation.

Similarly:

• treating anxiety without recognising underlying ADHD may lead to only partial improvement

• focusing solely on neurodevelopmental differences may overlook significant emotional distress

Management often involves a combination of approaches, including:

• medication where appropriate

• adapted psychological therapies

• practical strategies to support daily functioning

• environmental adjustments

• psychoeducation

  
  

Barriers to accessing appropriate care

For many individuals, accessing mental health care can be challenging, particularly when neurodevelopmental differences are present.

Barriers may include:

• differences in communication style

• sensory sensitivities in clinical environments

• difficulties with organisation or follow-through

• previous experiences of not being understood

Standard models of care do not always take these into account.

The importance of a clinically integrated approach

Effective care depends on clinicians being able to hold both aspects of a person’s presentation in mind, and to understand how they interact. This requires flexibility in communication, awareness of sensory needs, and adaptation of therapeutic approaches. A team-based approach can be particularly valuable in developing a shared understanding.

Why this matters for patients

For many people, the most difficult aspect of their experience is not a single symptom, but the sense that things do not quite fit together.

A thoughtful assessment and integrated approach can help clarify what is neurodevelopmental, what reflects mental health difficulty, how these interact, and what support is likely to be most helpful.

Moving beyond either/or thinking

The relationship between ADHD, autism and mental illness is not best understood in terms of either/or, it is often both.

Recognising this allows for more accurate diagnosis, safer treatment, and a more compassionate understanding of people’s experiences.

You can read more about what to expect from any assessment in the Effra Clinic here

Critchley H, Minnis H, Gajwani R, et al. The elephant in the room: neurodivergence in psychiatry. BJPsych, 2026.