ADHD patients with a psychiatric comorbidity more likely to stop taking their ADHD medicine

Reviewed by Emily Henderson, B.Sc.Jul 8 2021

A research study from the The Lundbeck Foundation Initiative for Integrative Psychiatric Research iPSYCH shows that people with ADHD, who also have another psychiatric diagnosis, are more likely to stop taking their ADHD medicine.

ADHD is one of the most common psychiatric disorders in childhood and is commonly treated with medication. ADHD medicine can be divided into two groups: medicine that has a stimulating effect - also known as stimulants - and non-stimulants, which are often used if a person does not respond well to the other form of medicine.

The medication can be an effective way of reducing symptoms, by increasing individual's ability help focus and reduce hyperactivity and impulsivity.

A research result from iPSYCH now shows that people with ADHD, who also have another psychiatric diagnosis, have a higher risk of stopping their medication than people who 'only' have an ADHD diagnosis.

Fifty per cent stop taking the medication

According to research, although stimulants work for the majority of people with ADHD, the medications sometimes can cause side effects, and up to fifty per cent stop taking their ADHD medications within two years of beginning the treatment.

We discovered that people who have another psychiatric diagnosis in addition to ADHD, for example tics, anxiety, bipolar disorder or some form of substance abuse, to a greater extent stop taking their stimulant medication or switch to a non-stimulant ADHD medication."

Isabell Brikell, Study Lead Author, Researcher at iPSYCH

According to the researcher, this could potentially be due to a higher risk of side effects or a lower effect of stimulants in people with several diagnoses, for example, stimulants can in rare cases lead to tics, which may cause the person to stops taking their stimulantmedication or tries non-stimulants.

Positive effect on important areas

"It's important to understand why so many stop taking their ADHD medication. Prior research has shown that the treatment can have has a positive effects on important parameters such as school performance and a lower risk of accidents and injuries for people with ADHD," says Isabell Brikell.

The researchers also found evidence that a higher genetic risk of schizophrenia and bipolar disorder is associated with an increased risk of stopping stimulant medications.

The results have just been published in the scientific journal American Journal of Psychiatry, and the study is the largest of its kind to date.

The researchers have collected information from 9,133 people diagnosed with ADHD and their prescriptions for ADHD medications in Denmark since 1995. The study attempted to identify the genetic, clinical (age at time of ADHD diagnosis and other diagnosis) and socio-demographic factors, such as the parents education, income and psychiatric history, which may affect the risk of the person stopping theirADHD medication.

"Our findings confirm previous smaller studies by showing that certain psychiatric comorbidity may have a negative effect on the treatment outcomes for ADHD," says Isabell Brikell, and emphasises that the results are particularly interesting for clinicians working with ADHD, as they make treatment decisions when meeting new patients with ADHD.

"With more knowledge about why and who has an increased risk of interrupting their treatment, we can better equip clinicians to give these people more targeted treatment, monitoring and support," she says.

The researchers are currently in the process of analyzing genetic information on more than 20,000 people with ADHD to test whether the results of the study can be confirmed and extended.