Parkinson’s and Motivation: How SSRIs May Impact Apathy Levels

By: Grace Huff

Dawn Bowers
Dawn Bowers, Ph.D., ABPP-CN

A recent study highlights a potential link between selective serotonin reuptake inhibitors (SSRIs), a widely prescribed class of antidepressants, and increased apathy levels in individuals with Parkinson’s disease (PD). Apathy, a non-motor symptom that affects motivation, emotional engagement, and goal-directed behavior, is a common but often overlooked neuropsychiatric symptom of PD. This research sheds light on how SSRIs may worsen apathy symptoms and provides essential insights for healthcare providers treating PD patients.

The study was motivated by reports from Parkinson’s support groups at the University of Florida. Many participants described feeling more unmotivated or emotionally blunted, key signs of apathy, after beginning SSRI use to manage depressive disorders. These observations raised concerns about whether SSRIs might exacerbate apathy in a condition where dopamine levels are already reduced, impairing the reward system and increasing the risk of mood disorders.

Dr. Dawn Bowers, Ph.D., ABPP-CN, a neuropsychologist at UF’s Norman Fixel Institute for Neurological Diseases, and her team revisited this issue over a decade after their initial research suggested SSRIs could lead to higher apathy scores. The team’s decision to investigate further was driven by ongoing concerns about the potential adverse effects of SSRI use, particularly as they remain a common treatment for depression symptoms in PD patients.

The study evaluated data from 400 individuals with Parkinson’s disease, analyzing the relationship between SSRI use and apathy levels. Participants were assessed using tools like the Starkstein Apathy Scale (SAS) and the Beck Depression Inventory-II (BDI-II), which help differentiate apathy symptoms from depression symptoms. Results showed that 26% of participants were using selective serotonin reuptake inhibitors, and these individuals had significantly higher apathy scores compared to non-SSRI users. However, no similar link was found with other antidepressants, such as serotonin-norepinephrine reuptake inhibitors (SNRIs) or Wellbutrin.

The findings suggest that SSRIs, which work by increasing serotonin levels, may interfere with dopaminergic neurons—already compromised in PD—further reducing dopamine activity. This interaction between serotonin reuptake and dopamine levels appears to contribute to worsening apathy symptoms in PD patients. These results raise important questions about the appropriateness of SSRIs for managing depressive disorders in this population, especially given the complex interplay of cognitive changes and neuropsychiatric symptoms in Parkinson’s disease.

The study underscores the need to distinguish between depression symptoms and apathy symptoms in Parkinson’s disease. While depression involves feelings of sadness or guilt, apathy, a distinct non-motor symptom, manifests as difficulty initiating and sustaining actions. Failure to recognize these differences can result in ineffective treatment plans and poorer patient outcomes.

Dr. Bowers and her team advocate for exploring alternative therapies to mitigate the adverse effects associated with SSRI use. Options like SNRIs or Wellbutrin, which have activating properties, may better serve the needs of depressed patients without aggravating apathy levels. Additionally, non-pharmacological approaches, including cognitive behavioral therapy and behavioral programs like the Parkinson Active Living (PAL) initiative, offer promising strategies for managing apathy symptoms. The PAL program, delivered via telehealth, helps patients set motivational goals and engage in rewarding activities.

This research calls on neurologists and psychiatrists to carefully weigh the risks and benefits of SSRI use in Parkinson’s patients. By integrating pharmacological alternatives, behavioral interventions, and innovative therapies, healthcare providers can better address the unique needs of this population.

Dr. Bowers emphasized, “Hopefully, this study will bring more awareness of the prevalence of apathy in individuals with Parkinson’s disease and the detrimental effects unrecognized apathy can cause. Increased awareness will result in greater efforts to focus on treatments for apathy generally and in Parkinson’s disease specifically.”