Attention deficit hyperactivity disorder (ADHD) diagnoses have been increasing in recent years, particularly in England where an estimated 2.5 million people are affected. However, experts caution that some individuals diagnosed with ADHD may actually have other underlying medical conditions that produce similar symptoms, such as restlessness, difficulty concentrating, impulsiveness, and memory problems. These alternative diagnoses, if identified, could lead to treatments that are more targeted and potentially easier to manage.
The rise in ADHD diagnoses has coincided with growing concerns about the thoroughness of assessments, especially given waiting times for NHS evaluations can extend up to seven years in some regions. This has driven many to seek private evaluations, often conducted online, where investigations into other possible causes of symptoms may be less comprehensive.
Professor Dinesh Bhugra, former president of the Royal College of Psychiatrists, emphasizes the importance of accurate diagnosis. While affirming the need to support those with genuine ADHD, he notes that stimulant medications prescribed without a full diagnostic workup may not be effective and carry unknown long-term risks. “Professionals making ADHD assessments need to look at multiple facets rather than just running through a symptom checklist,” he said.
A 2023 review by Canadian psychiatrist Joseph Sadek highlighted several conditions that could be misdiagnosed as ADHD, including thyroid disorders, iron deficiency, and diabetes. For example, type 1 and type 2 diabetes can cause cognitive difficulties such as poor attention and memory issues. These conditions are identifiable through simple medical tests and are manageable through established treatments including insulin, dietary changes, and medication.
Thyroid dysfunction also mimics ADHD symptoms; hypothyroidism can lead to fatigue and brain fog, while hyperthyroidism may cause restlessness and concentration problems. Hormonal changes during perimenopause similarly produce symptoms resembling ADHD, complicating diagnosis in adult women. Dr. Dan Baumgardt of the University of Bristol stresses the importance of investigating new-onset symptoms in adulthood, as ADHD symptoms typically emerge in childhood.
Mental health conditions further complicate diagnosis since depression and anxiety share several overlapping features with ADHD, like poor concentration and restlessness. Dr. Baumgardt notes that these conditions frequently coexist, making professional evaluation essential to distinguish among them and determine appropriate treatments, which may include psychotherapy or antidepressants.
Nutritional deficiencies, particularly low iron and vitamin B12, can cause cognitive and attentional impairments and should be ruled out in ADHD assessments. Haematologist Dr. Sue Pavord advises screening for iron deficiency, especially in teenagers and young adults, as it is common and easily treated.
Sleep disturbances, such as insomnia and obstructive sleep apnoea, can also mimic or exacerbate symptoms associated with ADHD. The American Academy of Pediatrics recommends that sleep issues be assessed in individuals presenting with ADHD symptoms, as these disorders can disrupt attention and lead to hyperactivity.
Experts advocate for thorough, multidisciplinary evaluations that consider the onset and breadth of symptoms, rule out other medical causes, and tailor treatment accordingly. As ADHD diagnoses continue to grow, ensuring accurate assessments remains critical to delivering effective care.