Navigating the complexities of mental health treatment, the use of medication for enhancing mental acuity or managing psychological conditions has become widespread. This trend spans various age groups, with countless individuals turning to drugs like Ritalin to address attention deficits or as a means to sharpen mental focus. The implications of such pervasive medication use, particularly when combined with antidepressants for treating complex mental health conditions, are only now coming to light. This combination, aimed at addressing multifaceted mental health issues, might inadvertently lead to profound behavioral changes and a heightened risk of addiction.

A groundbreaking study published in Addiction Neuroscience, led by Professor Heinz Steiner, along with colleagues Dr. Lorissa Lamoureux, Joel Beverley, and Professor Michela Marinelli from Rosalind Franklin University, examined the effects of combining Ritalin with a common antidepressant, uncovering potential dangers of using them together. The study reveals how this drug combination can lead to unexpected behavioral shifts and a higher likelihood of cocaine use in rats, signaling a red flag for similar outcomes in humans.

Professor Steiner shared, “Our findings suggest that using these two medications together, a common practice, might lead to unexpected and potentially harmful behavioral changes.” This important research calls for careful consideration when prescribing these medications for attention issues and depression, due to the possible increase in risky behaviors.

“We discovered that the mix of Ritalin and the antidepressant significantly raised activity levels in these animals, a reaction that could imply a higher inclination towards taking risks among humans,” Professor Steiner further explained, emphasizing the possible implications for patients. The study used innovative methods to closely monitor the animals’ movements and other behaviors, offering valuable insights into how such drug combinations might act as a stepping stone towards substance misuse.

“This study highlights the intricate ways these medications interact with the brain’s reward system, marking an essential step in understanding how treatments for attention issues and depression could unintentionally lead people towards substance misuse disorders,” Professor Steiner concluded. The results urge a reevaluation of current prescribing practices, highlighting the need for a more nuanced understanding of how different medications interact and their broader effects. Professor Steiner and his colleagues explored the behavioral impacts of combining methylphenidate (MP), commonly known as Ritalin, with fluoxetine (FLX), a widely used antidepressant. While FLX alone did not significantly alter behavior, its combination with MP amplified MP-induced actions, particularly in certain subgroups of rats. These subgroups displayed varied reactions: one with enhanced movement followed by intense repetitive behaviors leading to movement reduction, and another with gradual increase in movement but with only minimal repetitive behaviors. These diverse responses to the drug combination were associated with different reactions to cocaine exposure two weeks later, with the former subgroup, but not the latter, seeking and taking more cocaine, highlighting a complex interplay between these medications and the potential for increased vulnerability to substance misuse in specific subgroups of individuals. Professor Steiner and his team emphasize the need for cautious use of MP+FLX combinations, particularly due to their implications for the risk of substance use disorder.


Heinz Steiner et al., “Fluoxetine potentiates methylphenidate-induced behavioral responses: Enhanced locomotion or stereotypies and facilitated acquisition of cocaine self-administration,” Addiction Neuroscience, 2023.  DOI:


Dr. Heinz Steiner, Ph.D.

Dr. Heinz Steiner, Ph.D. – Dr. Heinz Steiner is a Full Professor of Cellular and Molecular Pharmacology at the Chicago Medical School, Rosalind Franklin University of Medicine and Science, and a Principal Investigator in the Stanson Toshok Center for Brain Function and Repair at Rosalind Franklin University. Dr. Steiner received his M.S. in Biology from the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, and his Ph.D. in Physiological Psychology from the University of Dusseldorf, Germany. After post-doctoral work at the National Institute of Mental Health, Bethesda, he was a Research Assistant Professor in the Department of Anatomy and Neurobiology at the University of Tennessee, College of Medicine and The Center for Neuroscience in Memphis. He joined the faculty in the Department of Cellular and Molecular Pharmacology at the Chicago Medical School in 2000, and was department chair from 2011-2022. Dr. Steiner’s research focuses on the functional organization of the basal ganglia and related brain systems, especially on the role of the neurotransmitters dopamine and serotonin in the regulation of basal ganglia – cortical interactions. One of the main objectives of his work is to understand how treatments with dopaminergic and serotonergic drugs produce changes in gene regulation in the basal ganglia and their consequences for drug addiction and other brain disorders. Dr. Steiner is the senior editor of the “Handbook of Basal Ganglia Structure and Function” and a co-editor of Elsevier’s “Handbook of Behavioral Neuroscience” series.

Dr. Michela Marinelli

Dr. Michela Marinelli is an Associate Professor of Neuroscience at the University of Texas at Austin, with affiliate appointments in the Department of Neurology, the Department of Psychiatry and Behavioral Sciences, and in the Division of Pharmacology and Toxicology. Dr. Marinelli obtained her B.S. in Pharmacy at the University of Rome “La Sapienza” (Italy) and her Ph.D. in Neuroscience and Pharmacology at the University of Bordeaux 2 (France). After a post-doctoral training in the United States, she was hired as an Assistant Professor by the INSERM (the French equivalent to the American NIH). Three years later, in 2003, she was recruited by the Dept. of Cellular & Molecular Pharmacology, at Rosalind Franklin University of Medicine & Science, in North Chicago. After ten years at that University, she moved to the University of Texas at Austin, where she currently works. Dr. Marinelli’s main research seeks to understand the neurobiological bases of drug addiction. The team uses a “systems approach”, which means that they examine and integrate different levels of information to understand how systems work and interact. These variables are studied in rodent models, and they range from the cellular and molecular level to the whole animal level. Dr. Marinelli has published over 50 publications in peer-reviewed journals and her work has been cited over 8000 times.