Coexisting Conditions That Mask ADHD Symptoms

Discover tips, treatment options, and support strategies from the Finding Focus Care Team

Last Update: June 2nd, 2025 | Estimated Read Time: 8 min

For many adults, particularly those aged 16 to 55, the signs of Attention-Deficit/Hyperactivity Disorder (ADHD) may be hidden in plain sight. Rather than recognizing ADHD, individuals are often diagnosed with anxiety, depression, or even personality disorders. In reality, ADHD frequently co-occurs with other mental health conditions, which can obscure its core symptoms. This overlap complicates diagnosis and treatment, leaving many adults feeling misunderstood, overwhelmed, and chronically frustrated.

This article explores how coexisting psychiatric conditions can mask ADHD in adults, why accurate diagnosis matters, and what red flags may signal underlying ADHD. It also offers psychological insights and evidence-informed strategies to support recognition and treatment.

Understanding ADHD in Adulthood

ADHD is a neurodevelopmental disorder that affects attention, impulse control, emotional regulation, and executive functioning. While traditionally associated with children, approximately 50 to 70 percent of individuals diagnosed in childhood continue to experience significant symptoms into adulthood (Asherson et al., 2016). Yet many adults remain undiagnosed due to several factors:

• Early symptoms may have been subtle or misinterpreted.
• Individuals may have developed strong compensatory strategies.
• Comorbid conditions may have overshadowed ADHD symptoms.

These individuals often report feeling like they must exert disproportionate effort to manage daily tasks, maintain organization, and sustain relationships. Without a diagnosis, they may internalize these difficulties as personal failings rather than manifestations of a neurological difference.

Coexisting Conditions and Diagnostic Challenges

ADHD seldom exists in isolation. In fact, research indicates that nearly 80 percent of adults with ADHD have at least one comorbid psychiatric condition (Kessler et al., 2006). The most common include anxiety disorders, depressive disorders, bipolar disorder, substance use disorders, obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). These coexisting conditions can either mask ADHD or be misinterpreted as the primary diagnosis.

Anxiety Disorders

Anxiety is one of the most frequent comorbidities in adults with ADHD. Symptoms such as restlessness, difficulty concentrating, and irritability are common to both conditions, complicating differential diagnosis. For some, anxiety develops secondarily in response to the chronic stress of managing undiagnosed ADHD. These individuals may experience intense worry about forgetting obligations, underperforming at work, or disappointing others, all of which can stem from executive functioning deficits intrinsic to ADHD.

When anxiety is treated without addressing ADHD, individuals may notice modest improvements in mood but continued difficulty with focus, time management, and task completion. This persistence suggests that anxiety may be a symptom rather than the root cause of their challenges.

Depressive Disorders

Similarly, major depressive disorder frequently coexists with ADHD. Symptoms such as low motivation, difficulty initiating tasks, sleep disturbances, and impaired concentration are shared by both conditions. However, in the context of ADHD, these symptoms may be driven by chronic frustration, social difficulties, or a pervasive sense of underachievement.

Many adults with undiagnosed ADHD report feeling demoralized by their inconsistent performance and strained relationships. In such cases, depression may be secondary, resulting from years of perceived failure and internalized self-criticism. Michelini et al. (2021) note that effective treatment of ADHD in adults can lead to improvements in depressive symptoms, further underscoring the importance of accurate diagnosis.

Substance Use Disorders

Another significant but often overlooked comorbidity is substance use disorder. Adults with ADHD may turn to alcohol, nicotine, cannabis, or stimulants in an attempt to manage symptoms such as impulsivity, boredom, and emotional dysregulation. While the substance use may be addressed in treatment, the underlying ADHD is frequently missed.

Research suggests that treating ADHD can reduce the likelihood of ongoing substance misuse, particularly when intervention occurs early. Clinicians must consider whether substance use behaviours may be compensatory, signalling an unmet need for regulation or focus.

Bipolar Disorder and Emotional Dysregulation

Bipolar disorder is another condition that can be confused with ADHD, particularly when emotional impulsivity and mood variability are prominent. However, there are key differences. While ADHD-related mood changes are typically brief and reactive, bipolar mood episodes are sustained and cyclical.

Clinicians must assess the duration, context, and functional impact of mood symptoms. A diagnosis of bipolar disorder may lead to treatment with mood stabilizers, yet the individual's difficulties with attention, organization, and emotional regulation may persist if ADHD remains unaddressed. Asherson et al. (2016) emphasize that proper differentiation between the two disorders is critical to effective treatment planning.

Recognizing Red Flags for Undiagnosed ADHD

Despite overlapping features, there are specific patterns that suggest underlying ADHD. These include:

• Longstanding disorganization and difficulty completing tasks, despite motivation.
• History of academic or occupational underachievement that does not align with intellectual ability.
• Chronic lateness, forgetfulness, or frequent misplacement of items.
• High levels of distractibility and difficulty sustaining attention in non-stimulating tasks.
• Emotional reactivity, including irritability and frustration over minor issues.
• Previous diagnoses of anxiety or depression with limited improvement in executive functioning.

Individuals who identify with several of these patterns may benefit from a formal ADHD assessment.

Moving Toward Clarity and Support

Recognizing ADHD in the presence of coexisting conditions requires a nuanced and comprehensive evaluation process. Clinicians should take a detailed developmental history, consider symptom patterns across the lifespan, and use validated diagnostic tools. When ADHD is identified, integrated treatment approaches that address both the core symptoms and comorbidities can offer the most effective support.

Effective interventions may include pharmacotherapy, cognitive-behavioural therapy, ADHD coaching, and lifestyle modifications that support structure and self-regulation. With proper diagnosis and treatment, adults with ADHD often experience substantial improvements in functioning, self-esteem, and quality of life.

Conclusion

ADHD in adults is frequently concealed by coexisting mental health conditions. While these comorbidities are valid and significant in their own right, they can obscure the presence of ADHD, leading to incomplete or ineffective treatment. By increasing awareness of how conditions like anxiety, depression, and substance use disorders can mask ADHD, clinicians and individuals alike can move toward more accurate diagnoses and meaningful interventions.

Finding Focus Care Team 

We are a group of nurse practitioners, continuous care specialists, creators, and writers, all committed to excellence in patient care and expertise in ADHD. We share content that illuminates aspects of ADHD and broader health care topics. Each article is medically verified and approved by the Finding Focus Care Team. You can contact us at Finding Focus Support if you have any questions!  

References

Asherson, P., Buitelaar, J., Faraone, S. V., & Rohde, L. A. (2016). Adult attention-deficit hyperactivity disorder: key conceptual issues. The Lancet Psychiatry, 3(6), 568–578. Link  

Kessler, R. C., Adler, L., Barkley, R., et al. (2006). The prevalence and correlates of adult ADHD in the United States: Results from the National Comorbidity Survey Replication. American Journal of Psychiatry, 163(4), 716–723. Link  

Michelini, G., Kitsune, G. L., Cheung, C. H., Brandeis, D., Banaschewski, T., Asherson, P., McLoughlin, G., & Kuntsi, J. (2016). Attention-Deficit/Hyperactivity Disorder Remission Is Linked to Better Neurophysiological Error Detection and Attention-Vigilance Processes. Biological psychiatry, 80(12), 923–932. Link    

Wilens, T. E., & Morrison, N. R. (2011). The intersection of attention-deficit/hyperactivity disorder and substance abuse. Current Opinion in Psychiatry, 24(4), 280–285. Link