Parkinson disease: Nursing pathophysiology

Parkinson disease, or PD, is a progressive neurodegenerative disorder that primarily impacts movement and results from loss of dopamine-producing neurons in the brain.

Now, motor activity is regulated by complex neural circuits within the brain. One of the main structures responsible for motor activity is the basal ganglia, also called the basal nuclei, located deep within the cerebral hemispheres of the brain.

The basal ganglia are a group of interconnected structures that are mainly involved in the planning, execution, and termination of motor activity through their connection with other parts of the brain. These include the thalamus, which serves as a major relay station in the brain, and cerebral cortex, which is responsible for many of the brain’s higher functions like reasoning and problem-solving and which also contains the motor cortex.

One important part of the basal ganglia is called the substantia nigra. This structure contains dopaminergic neurons that produce dopamine, a neurotransmitter involved in motor function and the fine-tuning of movements. Dopamine also inhibits the excitatory effects of neurotransmitters produced in other parts of the basal ganglia, like acetylcholine.

In addition to its key role in motor activity, the basal ganglia are also involved in coordinating cognitive, behavioral, and emotional functions through connections to the limbic system, which like the basal ganglia, is a group of interconnected structures. The limbic system is sometimes called the emotional brain due to its role in regulating emotions and behavior.

Okay, so PD is classified as primary, or idiopathic, and secondary, or acquired. Although there’s no known cause for most cases of primary PD, the incidence increases with age.

Other cases are related to familial or genetic factors, including those associated with the formation of Lewy bodies, which are aggregations of dysfunctional proteins in the brain, called alpha-synuclein, that play a role in neurotransmission, including regulating dopamine release. Lastly, those who are biologically male have an increased risk of PD.

On the other hand, secondary PD is caused by conditions like head trauma, infection, or brain tumors; or through exposure to environmental toxins, such as pesticides, herbicides, and heavy metals. Additionally, certain medications, like antiemetics or neuroleptics, can cause PD, which is typically reversible.

Now, regardless of the cause of PD, pathophysiology includes mitochondrial dysfunction from oxidative stress, along with the loss of nerve growth factors.

This results in degeneration of dopaminergic neurons in the substantia nigra and a deficiency of dopamine.