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New Study: Can People with Parkinson’s Experience Apathy and an Impulse Control Disorder at the Same Time?

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Historically described as being on opposite ends of the spectrum, apathy affects about 40% of people with Parkinson’s disease (PD), while impulse control disorders (ICDs) affect between 14% and 40% of people with PD. How are they different?

Apathy ― which comes from the French, apathie, meaning “passionless existence” ― is the feeling of being emotionally flat, lacking enthusiasm or interest in doing anything. Apathy can express itself in different ways, often leading people who experience it to stop exercising, keeping up with friends and family or even stop taking medications. Of note, apathy is often confused with depression, but they are not the same: with depression, there’s a profound sense of feelings of guilt and worthlessness.

Impulse Control Disorders (ICDs) are the inability to stop doing something that is harmful, or could become harmful, to yourself or others to the point that they impair one’s ability to function at work, home and navigate day-to-day life. Performing the activity can lead to a feeling of elation. Examples include online gambling, compulsive shopping and hypersexuality.

Since apathy and ICDs elicit opposite feelings, is it possible for a person with PD to experience both at the same time? It seems counterintuitive, but may not be. A study recently published in the journal, Neurology, “Co-occurrence of apathy and impulse control disorders in Parkinson’s disease”(Scott et al., 2020) sought to explore whether a lack of motivation or interest can co-exist with an irresistible urge to perform activities.

Michael S. Okun, MD, Parkinson’s Foundation National Medical Director, and the team of study co-authors utilized a convenience sample of 887 people with PD from the University of Florida Norman Fixel Institute for Neurological Diseases, a Center of Excellence, and characterized them by disease combination; they used a variety of tests to measure apathy, depression, anxiety, cognition and ICD.

Demographic data were taken, including PD onset, disease severity, as well as medication use. Medication was of particular interest because in addition to relaying messages that plan and control body movement, dopamine also plays a primary role in the reward pathway in one’s brains (the “feel-good” chemical).

Study participants included those with Parkinson’s experiencing:

  • An impulse control disorder (ICD): those with clinically significant ICD symptoms only
  • Apathy: those with clinically significant apathy symptoms only
  • Both: those with both clinically significant apathy and ICD symptoms
  • Neither: those with neither clinically significant apathy nor ICD symptoms


  • 61.6% of study participants had both ICD symptoms and apathy
  • 41.3% of study participants with apathy also had ICD symptoms
  • The ICD-only group had higher daily dopamine agonist medication use than patients in the apathy group
  • There was no significant difference in dopamine agonist use between the Neither group and the apathy group
  • Anxiety and depression each positively correlated with both apathy and ICD symptoms, separately

What Does It Mean

Woman pondering

A person with PD can indeed experience both apathy and ICDs ― suggesting they are not on opposite sides of the spectrum. In fact, a significant majority (62%) of those with PD in this study with ICDs had clinically significant apathy; while 41% of people with PD experiencing apathy also had ICD symptoms. Further, having both apathy and one or more ICDs resulted in having the highest levels of anxiety and depression.

“The findings from this study challenge the longstanding dogma that apathy cannot co-exist with impulse control behaviors. Although it seems counterintuitive, clinicians should appreciate this possibility.”

- Dr. Okun

This study suggests that it is imperative that clinicians, researchers, healthcare providers and care partners consider that these two PD symptoms are not mutually exclusive ― you can experience both at the same time. Knowing that someone with PD could have apathy and ICDs simultaneously, could profoundly impact clinical study designs, how novel medications are designed and tested, the approach (and mindset) of caregivers, and perhaps how those with PD think about themselves.

Learn More

The Parkinson’s Foundation believes in empowering the Parkinson’s community through education. Learn more about apathy and impulse control by visiting the below Parkinson’s Foundation resources, or by calling our free Helpline at 1-800-4PD-INFO (473-4636) for answers to all your Parkinson’s questions.

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