A nationwide Finnish study has revealed that adults diagnosed with attention-deficit hyperactivity disorder (ADHD) often reduce their use of antidepressants after starting ADHD treatment. Published in Acta Psychiatrica Scandinavica, the research suggests that properly identifying and addressing ADHD may decrease the need for other psychiatric medications, particularly among adults previously treated for depression or anxiety.
ADHD is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. While frequently associated with children, ADHD often persists into adulthood and may remain undiagnosed, particularly when its symptoms overlap with mood disorders. Many adults report long-term struggles with focus, task completion, and emotional regulation—challenges sometimes misattributed to depression or anxiety.
Standard ADHD treatments include stimulant medications such as methylphenidate and amphetamines, as well as non-stimulant options like atomoxetine or guanfacine. These treatments target core ADHD symptoms and can improve functioning in work, school, and social relationships.
The research team noted that adults are often diagnosed with ADHD only after years of treatment for other psychiatric or physical conditions. Because ADHD frequently co-occurs with depression and anxiety, it can be misdiagnosed or overlooked, leading to the prescription of antidepressants or anti-anxiety medications before ADHD is recognized. The study aimed to examine how ADHD treatment affects the use of both psychiatric and non-psychiatric medications.
“There is active discussion about the increase in ADHD diagnoses and medication use, particularly in Finland. Using nationwide registries, we decided to investigate this phenomenon comprehensively,” said Tuire Prami, senior scientist at Oriola and lead study author.
The study analyzed national Finnish registers to identify individuals newly diagnosed with ADHD between 2015 and 2020. Prescription records, diagnostic codes, and special reimbursement data were used to confirm ADHD status. Each ADHD patient was matched with up to four control participants without ADHD, comparable by age, sex, and region.
Medication data spanned 2010 to 2021, tracking prescriptions for ADHD-specific medications as well as antidepressants, antipsychotics, antibiotics, and anti-inflammatory drugs. Researchers examined changes in medication use before and after ADHD diagnosis, comparing trends between patients and controls.
The study found that many adults had been taking antidepressants prior to their ADHD diagnosis, but usage significantly declined following initiation of ADHD treatment. This pattern was not observed in the control group, suggesting the reduction was linked to ADHD-focused care. Researchers believe that addressing ADHD directly may alleviate symptoms previously treated with antidepressants or anxiety medications.
Among children, a similar trend was noted for non-psychiatric medications. Prior to diagnosis, children with ADHD were more frequently prescribed antibiotics, anti-inflammatory drugs, and asthma medications. Following ADHD treatment, the use of these medications decreased more steeply compared with controls—a pattern that may reflect ADHD’s association with infections or allergies in early life, although the exact reasons remain unclear.
Medication adherence among ADHD patients was high, with 95% filling prescriptions at least once and 80% doing so within ten days of prescription. Persistence varied by age: young children remained on ADHD medication the longest, adolescents were the most likely to discontinue early, and adults showed moderate persistence. Seasonal trends were observed, with school-aged children and teenagers reducing ADHD drug use during summer breaks.
Methylphenidate was the most commonly prescribed initial medication. Younger children often received sustained-release forms, while adolescents and adults were more likely to receive extended-release versions. Some patients later switched to medications such as lisdexamphetamine or atomoxetine, reflecting individual responses and side effects.
The study also noted that adults with ADHD were more likely to have used antiepileptics, antipsychotics, and sleep aids prior to diagnosis, reinforcing the idea that undiagnosed ADHD may contribute to complex medication histories.
“ADHD can be challenging to diagnose, especially in adults, who often first receive treatment for depression or other symptoms,” Prami said. “Once ADHD medication is prescribed, adherence is generally high. Supporting adolescents and their families during treatment remains crucial to maintain continuity of care.”
While the study does not definitively prove that ADHD treatment reduces the need for antidepressants, the observed trends suggest that improved diagnosis and treatment of ADHD could streamline psychiatric care.
The study, “Use of Antidepressants Decreased After Initiation of ADHD Treatment in Adu
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