Mental Health

January 4, 2023

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The significant impact of undiagnosed Autism and ADHD

Waiting lists for autism spectrum conditions are at an all-time high and some patients with ADHD are waiting as long as four years to be diagnosed. We’ve looked at the evidence to understand the impact that such lengthy waits are having on the livelihoods of the population.

Previous research overwhelmingly shows that both autism spectrum conditions and ADHD need to be diagnosed as soon as possible, to allow people to make necessary adaptations to their lives and prevent symptoms from worsening whilst they wait for critical treatment to begin.


The NHS does not publish ADHD waiting times in the same way that they are published for autism, however it is estimated by The Observer through freedom of information requests sent to NHS trusts that many patients wait a minimum of a year to receive a diagnosis, and the longest wait recorded is almost four years. A 2019 study found that living with untreated ADHD is associated with an estimated 12.7 year shorter estimated life expectancy, which highlights the urgency of diagnosing and treating the condition as early as possible.

Extensive research has been conducted into the detrimental impact of untreated ADHD on health and lifestyle. Adults with ADHD have a significantly lower quality of life and have significantly more difficulties obtaining and maintaining employment compared to those who don’t. A review of existing studies found that untreated ADHD can lead to deficits in academic achievement, substance and alcohol abuse, financial and employment difficulties, higher rates of criminality and antisocial behaviour, and increased rates of comorbid mental health disorders such as anxiety and depression.

Further complexities arise when we consider how diagnosing ADHD is not simple due to common overlapping symptoms between ADHD and mood or anxiety disorders and substance use disorders. This shows us how diagnosing and treating ADHD is not a one size fits all approach and requires the complex coordination of multiple different healthcare teams to provide personalised care – a factor that no doubt contributes to the extreme delays we are seeing.


As discussed in our earlier blog, waiting lists for autism are at a record high, and similarly to ADHD, living with undiagnosed autism has a profound effect on wellbeing. Many people with autism discuss how they go most of their lives not knowing their diagnosis and can be driven to crisis point because of this.

Due to the range and complexity of autism symptoms, it is commonly misdiagnosed due to the overlap with mental health conditions including social anxiety, eating disorders, personality disorders, obsessive compulsive disorder and psychosis.

In the most severe cases of untreated autism spectrum conditions, people can end up hospitalised in a mental health unit and subject to inappropriate treatment. Research has also found that once hospitalised, the average length of stay for an autistic person in a mental health hospital is 5 and a half years, where many patients deteriorate during this time due to the environment being unsuitable.

Patients are being failed by long waiting times that see their mental health and important aspects of their lives, such as career and social life, decline and deteriorate. Not only does this have a profound impact on the individual’s wellbeing, deterioration of psychological and lifestyle factors can lead to other issues that require medical or social intervention – putting additional burden on the already strained healthcare system. Additionally, our analysis reveals the complexity of diagnosing autism and ADHD due to overlapping symptoms with other mental health conditions, highlighting how every patient needs a personalised approach and coordination of multiple services that requires additional resource. The NHS cannot on its own deliver this level of service at the pace that is required.

To address this unmet need, the NHS can look to new ways of working and consider private sector partnerships to truly transform diagnosis and care for the better. CHS Healthcare are offering remotely delivered autistic spectrum condition and ADHD assessments to help NHS partners reduce waiting lists and add essential clinical capacity to struggling services. Contact Ellie Norman ( or Sam Jordan ( to find out more.

As originally seen on LinkedIn

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