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1- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
2- Department of Neurology, Rasoul Akram Hospital, Iran University of Medical Science, Tehran, Iran.
3- Department of Neurology, Rasoul Akram Hospital, Iran University of Medical Science, Tehran, Iran
4- Department of Neurosurgery, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
2- Department of Neurology, Rasoul Akram Hospital, Iran University of Medical Science, Tehran, Iran.
3- Department of Neurology, Rasoul Akram Hospital, Iran University of Medical Science, Tehran, Iran
4- Department of Neurosurgery, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
Abstract:
Background: Apathy as a neuropsychiatric disorder has been reported in Parkinson's disease (PD) after subthalamic deep brain stimulation (STN-DBS). Theunderlying mechanism by which this occurs is not known;hence, we investigated the structural and functional changes of serotonergic system in PD patients underwent STN-DBS with pure apathy.
Methods: Twenty-three PD patients underwent STN-DBS and 10 healthy controls (HC) were recruited. PD patients divided into pure apathy (PDA) (n = 10) and without apathy (PDNA) (n = 13) groups. We evaluated the effects of bilateral STN-DBS on the serotonergic brain regions by structural (Diffusion tensor imaging) and functional (resting‐state functional MRI) neuroimaging techniques. Clinicaland neuropsychiatry assessment was performed before and after DBS. Apathy was evaluated with the Apathy Evaluation Scale (AES).
Results: The results showed that STN-DBS significantly induces pure apathy in PDA patients, and there was significant correlation between apathy severity and serotonergic alterations. Apathetic group had reduced fractional anisotropy (FA) value in the dorsal raphe nucleus (DRN), left caudate nuclei, dorsolateral prefrontal cortex (DLPFC) and left nucleus accumbens (NAc). The apathy severity was associated with decreased functional connectivity (FC) in DRN, left caudate nucleus, medial orbitofrontal cortex and right amygdala in apathetic patients.
Conclusions: Our results demonstrated that pure apathy after STN-DBS is not necessarily association to dopamine withdrawal and stimulation had an inhibitory effect on the serotonergicsystem especiallyin the DRN. Our results enhance the knowledge for better defining the pathophysiology of induced apathy in PD patient and its therapeutic protocol in future.
Methods: Twenty-three PD patients underwent STN-DBS and 10 healthy controls (HC) were recruited. PD patients divided into pure apathy (PDA) (n = 10) and without apathy (PDNA) (n = 13) groups. We evaluated the effects of bilateral STN-DBS on the serotonergic brain regions by structural (Diffusion tensor imaging) and functional (resting‐state functional MRI) neuroimaging techniques. Clinicaland neuropsychiatry assessment was performed before and after DBS. Apathy was evaluated with the Apathy Evaluation Scale (AES).
Results: The results showed that STN-DBS significantly induces pure apathy in PDA patients, and there was significant correlation between apathy severity and serotonergic alterations. Apathetic group had reduced fractional anisotropy (FA) value in the dorsal raphe nucleus (DRN), left caudate nuclei, dorsolateral prefrontal cortex (DLPFC) and left nucleus accumbens (NAc). The apathy severity was associated with decreased functional connectivity (FC) in DRN, left caudate nucleus, medial orbitofrontal cortex and right amygdala in apathetic patients.
Conclusions: Our results demonstrated that pure apathy after STN-DBS is not necessarily association to dopamine withdrawal and stimulation had an inhibitory effect on the serotonergicsystem especiallyin the DRN. Our results enhance the knowledge for better defining the pathophysiology of induced apathy in PD patient and its therapeutic protocol in future.
Keywords: Parkinson’s disease, Apathy, Subthalamic deep brain stimulation, Serotonergic system, Magnetic resonance imaging.
Type of Study: Original |
Subject:
Cognitive Neuroscience
Received: 2026/08/6 | Accepted: 2026/09/22
Received: 2026/08/6 | Accepted: 2026/09/22
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