Parkinson's disease: Symptoms, Treatment, and New Hope

What is Parkinson's disease? A neurodegenerative disorder associated with loss of the dopaminergic (dopamine-producing) neurons in the substantia nigra of the brain, a part of the basal ganglia that provides stimulatory input to the cerebral cortex.

SYMPTOMS: Motor symptoms are a primary feature of Parkinson's and primarily include --a resting tremor that decreases with intentional (voluntary) movement, rigidity: stiffness and increased muscle tone, bradykinesia/akinesia: slowed or absent movement, postural instability and tendency to fall

Altered mood and cognitive disturbances
--slowed reaction time, executive/cortical dysfunction, dementia, a late occurrence in 20-40% of cases, short term memory loss, medication effects: some of the above cognitive disturbances are improved by dopaminergic medications, while others are worsened

Sensory disturbances (some of these are also noted in Alzheimer's disease)
--impaired higher visual perception, dizziness and fainting, impaired proprioception (the awareness of bodily position in space), reduction in or loss of sense of smell (microsmia or anosmia) - can occur years prior to diagnosis, pain, both neuropathic and musculoskeletal

Sleep disturbances
--Excessive daytime somnolence, insomnia, disturbances in REM sleep can occur years prior to diagnosis

Autonomic disturbances
--skin, bowel and bladder dysfunction (late stages)

CAUSES: Most cases are idiopathic, meaning that the cause is unknown. Specific cases may be caused by toxicity, drugs, or head trauma.

TREATMENT: L-dopa in various forms replaces the dopamine lost by death of neurons in the substantia nigra. Dopamine agonists mimic the effects of dopamine by stimulating dopamine receptors and eventually desensitizing them; thus, these drugs can help initially but eventually worsen symptoms.

The amount of dopamine in the brain is critical for many functions, including behavioral effects. Nearly all individuals with Parkinson's disease do NOT smoke or exhibit other addictions; if they did in the past, generally they stop with the onset of Parkinson's disease. Conversely, overmedication can lead to impulsiveness and other symptoms of excessive dopamine in the brain.

Parkinson's Disease and Adult Stem Cell Research

This study shows that bone marrow derived stem cells do incorporate into the brain as new cells and do not cause cancer.

The adult neural stem cell niche: lessons for future neural cell replacement strategies. Lim DA, Huang YC, Alvarez-Buylla A. Neurosurg Clin N Am. 2007 Jan;18(1):81-92, ix.

Recent work on neural stem cells provides hope for treating Parkinson's disease, stroke, multiple sclerosis, and traumatic brain injury. The adult rodent brain retains neural stem cells in two separate locations (niches) that continually generate new neurons: the subventricular zone of the lateral ventricle and the dentate gyrus subgranular zone of the hippocampus. Understanding how these niches affect stem cell function should aid in mobilizing endogenous stem cells to repair and regenerate injured or diseased brain tissue.

Find out more about Parkinson's disease and adult stem cell research

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Adult Stem Cells in Circulation

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