Q: What causes the movement problems associated with Parkinson’s disease?

A: Parkinson's disease is a progressive neurodegenerative movement disorder. The main symptoms of the disease are tremors, slowness, stiffness, and balance problems. These symptoms are known as the motor symptoms of PD. Besides motor symptoms, there are numerous non-motor symptoms, including thinking problems, depression, sleep difficulties, constipation and dizziness, urinary problems, hallucinations and behavioral disturbances.

Substantia nigra is an area of the brain that produces a chemical called dopamine. This area is fundamental for the smooth and organized execution of our movements. Substantia nigra slowly degenerates in PD, leading to the lack of dopamine. With substantial dopamine loss, motor symptoms of PD slowly emerge, and progressively get worse due to the ongoing neurodegeneration. We, however, do not know what causes degeneration of the substantia nigra.

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Memory decline and thinking problems are common non-motor manifestations of PD. The degree of thinking problems may vary from mild forgetfulness to more pronounced impairment called dementia. Memory and thinking problems are in most cases slowly progressive. Many other causes, besides PD itself, may cause thinking problems in the PD population. Examples include co-existent depression, other medical problems, poor sleep, and especially medication side effects. It is important that thinking and memory complaints are timely communicated to a neurologist. Detailed memory and thinking testing may be necessary to better characterize the type of thinking problem. Subsequently, alterations in the medication regimen and additions of medications for memory may be needed.