Can untreated ADHD and IQ lower apparent IQ?

PostedOctober 9, 2025

UpdatedOctober 13, 2025

ByMy Patient Advice

Author: Harriet Winslow, BSc | Reviewed by: Dr. Rebecca Fernandez, MBBS

Yes, untreated ADHD can lead to lower apparent IQ scores, but this is not an accurate reflection of an individual’s true intelligence. Untreated ADHD and IQ are connected in that ADHD symptoms, such as inattention, impulsivity, and difficulty with emotional regulation, can impair performance on IQ tests or in academic settings. These symptoms can prevent individuals from focusing on the tasks at hand, leading to poor test results that do not represent their intellectual capabilities.

When ADHD is left untreated, it can affect developmental outcomes, hindering academic success and limiting opportunities for people to showcase their cognitive abilities. This can result in a mismeasured intelligence, where individuals with ADHD appear less capable than they actually are due to challenges in completing tasks, following instructions, or staying focused.

How Untreated ADHD Affects IQ Scores

Inattention

Difficulty staying focused can cause individuals to miss key points or make errors during IQ tests, lowering their scores.

Impulsivity

Impulsive answers or behaviours can lead to inaccurate responses, particularly in timed environments.

Long-term effects

Over time, untreated ADHD can have lasting effects on academic and professional success, reinforcing the misconception that someone’s cognitive abilities are lower than they actually are.

In conclusion, untreated ADHD and IQ scores may not reflect true intelligence. With proper treatment and support, individuals with ADHD can often perform closer to their true potential, revealing a more accurate picture of their abilities.

Visit providers like ADHD Certify for personal consultations and expert advice tailored to your needs.   

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Myths about ADHD and intelligence.

Harriet Winslow, BSc

Author

Harriet Winslow is a clinical psychologist with a Bachelor’s in Clinical Psychology and extensive experience in behaviour therapy and developmental disorders. She has worked with children and adolescents with ADHD, autism spectrum disorder (ASD), learning disabilities, and behavioural challenges, providing individual and group therapy using evidence-based approaches such as CBT and DBT. Dr. Winslow has developed and implemented personalised treatment plans, conducted formal and informal assessments, and delivered crisis intervention for clients in need of urgent mental health care. Her expertise spans assessment, treatment planning, and behavioural intervention for both neurodevelopmental and mental health conditions.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy.

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.