Anomalies of the Aging Brain - Parkinson's Disease (1).docx

**Anomalies of the Aging Brain: Parkinson\'s Disease** A drawing of a person holding a hammer Description automatically generated **Parkinson\'s Disease:** is a progressive neurodegenerative disorder that primarily affects movement. It occurs due to loss of dopamine-producing neurons in the substa...

**Anomalies of the Aging Brain: Parkinson\'s Disease** A drawing of a person holding a hammer Description automatically generated **Parkinson\'s Disease:** is a progressive neurodegenerative disorder that primarily affects movement. It occurs due to loss of dopamine-producing neurons in the substantia nigra, which is located in the basal ganglia. The basal ganglia are a group of nuclei involved in coordinating movement. **Introduction** - **Comparison to Alzheimer\'s**: Unlike Alzheimer\'s, which affects memory first, Parkinson\'s disease primarily affects movement. **Nature of the Disease** - **Progressive Neurodegenerative Disorder**: Parkinson\'s involves the progressive degeneration of dopaminergic neurons in the basal ganglia. - **Clinical Presentation**: - **Tremors**: Shakiness and stiffness. - **Bradykinesia**: Slowed movements that are difficult to initiate. - **Balance Issues**: Problems maintaining balance. **Basal Ganglia and Pathways** - **Basal Ganglia**: - Subcortical area of the brain with several nuclei. - Key nuclei in Parkinson's: Substantia nigra and striatum. - **Pathway Communication**: - **Direct Pathway**: - Dopaminergic neurons from the substantia nigra signal the striatum: Cells in the substantia nigra send signals to the striatum using a chemical called dopamine. - Dopamine is deposited in the striatum and the message is passed through the thalamus to the cortex, facilitating movement: This signal helps the brain tell the body to move. - **Analogy**: Think of the thalamus as an excited puppy that loves to move when it gets dopamine. - **Indirect Pathway**: - Works through other neurons in the basal ganglia to fine-tune or decrease movements: Another set of brain cells helps control or limit movement. - **Analogy**: This pathway is like a leash that keeps the excited puppy in check. **Pathway Dysfunction** - **Direct Pathway Problem**: In Parkinson's, the direct pathway fails to increase movement due to reduced dopamine, leading to bradykinesia: In Parkinson's, the direct pathway doesn\'t work well because there's not enough dopamine. This makes it hard to start and control movements. - **Shut Down by Lewy Bodies**: The nigrostriatal pathway is shut down due to the accumulation of Lewy bodies: Clumps of protein called Lewy bodies build up in brain cells and disrupt signals. **Lewy Bodies** - **Composition**: - Comprised of a protein called α-synuclein. - Accumulation of α-synuclein interferes with cell signaling. - **Neuronal Degeneration**: - Neurons with Lewy bodies degenerate and eventually die. - When 80% of neurons in the nigrostriatal pathway degenerate, bradykinesia and other symptoms appear. - Movements become rigid, jerky, and uncoordinated, leading to tremors. **Disease Progression** - **Spread to Other Brain Regions**: Parkinson's can spread, leading to dementia. - **Lewy Bodies\' Role**: Unclear if Lewy bodies cause or result from Parkinson's. - **Idiopathic Nature**: Most cases are idiopathic (unknown cause); 15% have a genetic link. **Environmental Factors and Risk** - **Pesticide Exposure**: High correlation with Parkinson's in agricultural workers. - **Chemical Exposure**: Exposure to cleaning chemicals and heavy metals increases risk. - **Concussions**: History of concussions linked to Parkinson's and other dementias. - **Gender Risk**: More common in males than females. \_\_\_\_\_\_ Which of the following statements regarding the onset of Parkinson\'s disease is true? - The pathology starts in the basal ganglia Which of the following is true regarding the pathophysiology of Parkinson\'s disease? - Lewy bodies accumulate in the nigrostriatal pathway, interrupting excitatory dopaminergic neuronal signaling in the direct movement pathway. Which of the following symptoms is typically not seen until the end-stage of Parkinson\'s disease progression? - Dementia Which of the following has NOT been linked to the development of Parkinson\'s disease? - Top of Form - History of cardiovascular disease