Parkinson's disease is characterized by movement-related symptoms like tremors, rigidity, and slowness, but approximately half of patients also experience neuropsychiatric problems, including cognitive and sleep issues, depression, anxiety, and even psychosis. A collaborative research team has been awarded a four-year, $3 million grant from the Department of Defense (DOD) to investigate the underlying causes of these neuropsychiatric symptoms in Parkinson's disease (PD). The research aims to improve the lives of PD patients and the management of their symptoms.
The grant is divided among researchers at Binghamton University, the Barrow Neurological Institute in Arizona, and the University of Illinois in Chicago. The team, already collaborating on an NIH-funded project, brings together expertise in neuroanatomy, neuroimaging, neurophysiology, and neurochemistry.
Serotonin's Role in Parkinson's Neuropsychiatric Symptoms
Clinical studies have linked changes in serotonin-producing neurons to PD. Research indicates that serotonin neurons can unexpectedly produce dopamine when exposed to L-DOPA, a common PD treatment. However, this dopamine release is uncontrolled, leading to significant side effects. According to Binghamton University Psychology Professor Christopher R. Bishop, "It’s almost as if the systems get hijacked and tip over into aberrant neuroplasticity. The severity of the disease is the tipping point and adding treatment on top of disease progression."
Investigating Cellular Changes and Potential Treatments
Using new techniques, researchers are modifying specific cell types in animal models to study and stimulate them with chemo-genetic tools. Initial results show that animals with specific cellular changes exhibit increased anxiety levels. The researchers have identified several medications that could potentially be repurposed to treat serotonin dysfunction in PD. Their partnership with the Muhammad Ali Parkinson Center, a NeuroNEXT clinical trial site, provides access to a large PD patient population and clinical trial expertise.
Global Compensatory Mechanisms
Bishop notes that non-motor symptoms of PD clearly originate from an organic source. Investigations using animal models and postmortem human brains have revealed similar plasticity in the movement system within areas involved in neuropsychiatric, cognitive, and sleep-related functions, suggesting a more global compensatory mechanism in the disease.
