By Rebecca Bourke, IACP Counsellor | Last Reviewed: February 2026

Quick Summary: ADHD is a highly heritable (70-80%) neurodevelopmental disorder affecting 2.5% of adults. It is characterized by delayed cortical maturation and executive dysfunction, but remains highly treatable through a combination of pharmacology and CBT.

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What Exactly is ADHD?

Attention-Deficit/Hyperactivity Disorder (ADHD) is a persistent neurodevelopmental disorder. While historically misunderstood, modern research identifies it as a disorder of functional capacity. It primarily affects how brain networks communicate to regulate attention, impulses, and activity levels.

The Persistence of ADHD into Adulthood

A common misconception is that children “outgrow” ADHD. However, longitudinal studies (Faraone et al., 2015) show:

• 71% of patients continue to experience significant functional impairment in adulthood.
• 65% retain impairing symptoms, even if they no longer meet the full pediatric diagnostic criteria.

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What Causes ADHD? Genetics and the Environment

ADHD is not caused by lifestyle choices or “bad parenting.” It is one of the most heritable conditions in psychiatry.

1. Genetic Factors

Research indicates a heritability rate of 70–80%. This is driven by:

• Polygenic Risk: Thousands of common genetic variants that together increase susceptibility.
• Copy Number Variants (CNVs): Rare insertions or deletions in DNA that affect neurotransmitter signaling, specifically the nicotinic α7 acetylcholine receptor and glutamate receptors.

2. Neurobiology and Brain Structure

Neuroimaging reveals that ADHD brains often show a 3-year delay in cortical maturation, particularly in the prefrontal cortex.

• Structural Differences: Reduced volume in the caudate nucleus, putamen, and amygdala.
• Functional Connectivity: Lower connectivity within the Default Mode Network (DMN), leading to difficulties in “switching off” distracting thoughts.

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Executive Functioning: The Brain’s “Manager”

If you have ADHD, your brain’s “Executive Functioning” system—the internal manager that plans and executes tasks—is underactive. This leads to challenges in:

• Working Memory: Difficulty holding and manipulating information.
• Reward Dysregulation: A biological preference for immediate rewards over long-term goals.
• Inhibitory Control: An inability to “brake” impulsive reactions.

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Evidence-Based Treatment Options

The goal of treatment is to manage symptoms and improve quality of life. According to clinical primers, the most effective approach is often multimodal:

Treatment Type	How it Works	Efficacy
Pharmacology	Stimulants (Methylphenidate) and non-stimulants target dopamine/noradrenaline transporters.	High; reduces symptoms markedly.
Cognitive Behavioral Therapy (CBT)	Builds “manual overrides” for executive deficits and emotional dysregulation.	Highly effective for adult functional impairment.
Neurodevelopmental Support	Parent training and environmental modifications.	Essential for children and family dynamics.

Is it time for professional support?

ADHD is a biological reality, not a character flaw. If you feel you are constantly “swimming upstream,” specialized support can help you navigate these neurobiological challenges. While I do not provide clinical evaluations, I specialize in helping clients develop the strategies and self-compassion needed to thrive with an ADHD brain.

Contact me to arrange a free consultation call or a session.

References:

Faraone, S. V., Bellgrove, M. A., Brikell, I., Cortese, S., Hartman, C. A., Hollis, C., Newcorn, J. H., Philipsen, A., Polanczyk, G. V., Rubia, K., Sibley, M. H., & Buitelaar, J. K. (2024). Attention-deficit/hyperactivity disorder. Nature reviews. Disease primers, 10(1), 11. https://doi.org/10.1038/s41572-024-00495-0

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