Which disease is characterized by progressive degeneration of the basal ganglia with loss of dopamine, causing tremor and rigidity and slowed voluntary movement?

• A. Parkinson's Disease
• B. Multiple Sclerosis
• C. Cerebral Palsy
• D. Motor Neurone Disease

Answer: (A)

This question tests understanding of how loss of dopamine in the basal ganglia leads to a characteristic movement disorder. When dopamine-producing neurons in the substantia nigra degenerate, dopamine in the striatum falls, disrupting the balance between the direct and indirect pathways that regulate movement. This causes slowed voluntary movement (bradykinesia), muscle rigidity, and a tremor that often sits at rest, with a progressively worsening course as degeneration continues. The other conditions don’t fit this combination: multiple sclerosis is a demyelinating disease with varied symptoms; cerebral palsy is non-progressive and due to early brain injury; motor neurone disease mainly affects motor neurons and leads to weakness and wasting rather than the classic tremor-rigidity-bradykinesia pattern. Therefore, the described pathology and symptoms align with Parkinson's disease.