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ADHD, Anxiety or Both - a Tricky Relationship

Published: 25 Oct 2021 | ADHD research

Anxiety is the most common type of psychiatric disorder across many countries [1] and frequently co-occurs with Attention Deficit Hyperactivity Disorder (ADHD). In fact, roughly one-third of children and nearly half of adults with ADHD meet the criteria for an anxiety disorder [2] [3]. So what happens when they co-exist? We decided to delve a little deeper...



Disclaimer: the information contained on this website does not constitute medical advice. If you have concerns about your own health or the health of someone else, you should speak to your doctor.

The characteristics of ADHD

ADHD is a neurodevelopmental disorder characterized by age-inappropriate levels of inattention, including organization difficulties, challenges maintaining attention, and making careless mistakes, as well as symptoms of impulsivity and/or hyperactivity including interrupting, talking excessively, inability to sit still, and feeling restless.

The characteristics of anxiety disorders

Anxiety disorders are characterized by excessive fear of perceived or imminent threat, elevated stress in anticipation of threat, increased worrisome thoughts, and other cautious or avoidant behaviors. An example may be someone who experiences high levels of anxiety in a social setting to a point where they avoid social situations such as meeting up with friends – this is known as avoidant behavior.

While anxiety is a normal reaction to stress and can be beneficial in some situations, anxiety disorders differ from normal feelings of nervousness or anxiousness. Anxiety disorders are the most common of mental disorders and affect nearly 30% of adults at some point in their lives [4].

How do ADHD and anxiety impact everyday life?

‘It takes me a lot of hard work to get my work turned in on time. I am very smart, but my grades drop sometimes.’

‘If I could actually sit down and start my homework, I would, but many days I just can’t, and struggling with something so seemingly simple tends to make me feel very frustrated or even stupid.’

source: This is What It's Really Like to Have ADHD, How to ADD

‘There is no way I am going to pass this exam – I don’t even want to show up.’

‘I was so uncomfortable about that party. It was hard for me to breathe and got all sweaty- I had to leave.’

Source: What is Anxiety? Psych Hub

Where ADHD and anxiety disorders may intersect

While ADHD and anxiety are separate disorders, they share symptoms of increased distractibility, difficulties concentrating, and sleep problems [5]. In the past decades, researchers have focused on understanding the clinical characteristics and mechanisms underlying ADHD and anxiety comorbidity (i.e., simultaneous presence of both conditions) and specifically whether the occurrence of both disorders together is associated with any differences in symptom presentation compared to either disorder alone.

This topic of research is of particular interest, considering the high rates of ADHD and anxiety comorbidity. Among the population of those with ADHD, the prevalence of at least one diagnosed anxiety disorder among preschool children is 4%, among school-aged youth is 18% and nearly half (47%) of adults with ADHD [6].

Dealing with ADHD can increase stress and worry as people find it difficult to focus or organize their tasks, and this may lead to underachievement at work or school. These daily functional challenges may increase the levels of anxiety experienced by individuals with ADHD over time.

On the other hand, rumination and excessive worrisome thoughts that characterize individuals with anxiety may directly interfere with attentional control and other, executive functions (EFs) such as the ability to pause or stop an ongoing response or switching attention between different tasks, and cause restlessness. In turn, these symptoms in the context of anxiety may drive subclinical ADHD to become clinical [7].

Without thorough evaluation, the bidirectional effects between ADHD and anxiety can lead to a missed diagnosis of one or the other condition, when both are present.

A clearer picture of the main mechanisms and clinical characteristics of the ADHD and anxiety comorbidity can lead to faster and more accurate diagnostic procedures, as well as identify better and more targeted interventions.

In a recent guest blog, Dr Venkat Reddy highlighted the importance of clinicians getting a complete history of each patient to understand what factors may be affecting their ability to concentrate, illustrating a hypothetical example:

“If a child is hungry, worried about parental mental health, or witnessing domestic violence at home, how can they possibly be expected to concentrate in the classroom? Without a comprehensive biopsychosocial assessment, it can be easy to jump to conclusions”. Read the complete blog here


So, what does comorbid diagnosis of ADHD and anxiety look like?

Studies have found that elevated anxiety symptoms in children and adolescents with ADHD are associated with more social problems, peer rejection, as well as lower social skills and social competence [8]. Among undergraduate college students with ADHD and anxiety, one study found increased difficulties regulating emotions, organizing thoughts and actions, and finding solutions to problems compared to individuals with ADHD-only or anxiety-only [9].

One may think that the presentation of both ADHD and anxiety together would manifest in an additive fashion so that problems associated with either disorder alone will be exacerbated when the two disorders co-occur. However, this is an issue that remains unclear with research findings providing mixed results. Some researchers suggest that the co-occurrence of both disorders may lead to exacerbation of symptoms in situations that require extra mental effort for working memory (holding new information in place so the brain can work with it briefly and connect it with other information) and other tasks that are cognitively more difficult or complex [10].

This was supported by studies that examined less complex cognitive tasks - sustained attention (i.e., ability to maintain focus for prolonged time) [11] on continuous performance tests and inhibitory control (individuals’ ability to withhold or stop an automatic response). The studies found that performance in children with comorbid ADHD/anxiety did not differ or was even better than those with ADHD-only [12–14].

However, further evidence has shown that in tasks that require immediate information processing (i.e., when a child needs to write the sentence their teacher has just said out loud), children with ADHD and anxiety have more working memory problems compared to those with ADHD-only [15].

What about treatment?

For ADHD, treatment with psychostimulants (e.g., methylphenidate and amphetamines) and non-psychostimulants (e.g., atomoxetine, clonidine, and guanfacine) are licensed due to their effectiveness in reducing the core symptoms of ADHD (inattention, hyperactivity, impulsivity). Other non-pharmacological treatments are also used to improve associated cognitive and behavioral problems (e.g., interpersonal challenges, parental conflicts, cognitive and working memory problems), especially for younger age groups.

While cognitive behavioral therapy (CBT) has been found to be beneficial for anxiety [16], the evidence supporting its benefits among individuals with comorbid ADHD /anxiety is limited. This raises the question of whether individuals with both conditions may benefit equally from CBT as do those with anxiety alone.

Interestingly, there is some evidence that, compared to placebo, the use of psychostimulant medications in children with ADHD-alone is associated with a reduced risk of anxiety [17]. In another study, a total of 69 children with ADHD with co-occurring anxiety symptoms, were randomly assigned to methylphenidate or atomoxetine for 8 weeks of treatment. The results showed that both medications significantly reduced the symptoms of ADHD and anxiety, with atomoxetine effectively reducing both inattentive and anxiety symptoms at the fourth week of treatment - sooner than methylphenidate [18]. 

As discussed in a recent review, there have been mixed results among other studies that have examined the effects of methylphenidate in those with ADHD and anxiety [17]. Some reported that response to treatment was lower for children with both ADHD and anxiety disorders and was associated with more side effects when compared to children with ADHD only, but the authors warn that these findings need to be further researched. Other studies have suggested that the benefits of stimulant medications on anxiety may be more pronounced in cases where anxiety is ‘secondary’ to ADHD (i.e., when anxiety is experienced as a result of ADHD symptoms). Further evidence suggests that the use of CBT as an adjunct to ADHD medication can lead to the reduction of ADHD and associated anxiety symptoms and improve daily functioning [19].

Overall, patients who have both ADHD and anxiety are less likely to benefit from CBT strategies alone and often need combined pharmacological treatments [20]. Finally, it is recommended that the most impairing condition should generally be treated first in instances of comorbidity [20].

To summarize, ADHD and anxiety frequently co-occur, causing challenges with daily functioning and may lead to misdiagnosis. While individuals with ADHD and anxiety may face more challenges with working memory, social and emotional functioning, in some cases, they may present with lower impulsivity levels that can facilitate simple tasks that require attentional focus but that are not particularly complex.

In terms of treatment options, there is evidence showing that ADHD medication may also improve anxiety symptoms, but results may differ depending on the primary diagnosis, age and other co-occurring conditions. Multi-modal treatment with both medication and CBT may benefit individuals with comorbid ADHD and anxiety.



A clinician’s perspective on ADHD and Anxiety

This is What It's Really Like to Have ADHD

What is Anxiety?


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