Parkinsons and Alzheimers

Parkinson's Disease (PD)

A progressive neurodegenerative disorder caused by degeneration of dopamine-producing neurons, resulting in decreased dopamine and relatively increased acetylcholine.

Pathophysiology of Parkinson's Disease

Dopamine decreases while acetylcholine becomes relatively excessive, producing the characteristic motor symptoms.

Clinical Manifestations of Parkinson's Disease

Motor: Tremor, rigidity, bradykinesia, postural instability. Other: Autonomic disturbances, sleep disturbances, depression, psychosis, and dementia.

Treatment Goals for Parkinson's Disease

Restore the balance between dopamine and acetylcholine to improve symptoms. Treatment controls symptoms but does not cure the disease.

Major Drug Classes for Parkinson's Disease

Dopaminergic agents increase dopamine activity. Anticholinergic agents decrease acetylcholine activity.

Major Parkinson Medications

Levodopa • Levodopa/Carbidopa (Sinemet) • Pramipexole • Selegiline • Benztropine.

Levodopa

Dopamine precursor that crosses the blood-brain barrier and is converted into dopamine within the CNS.

Advantages of Levodopa

Dopamine cannot cross the blood-brain barrier, but levodopa can. It also has a sufficient half-life for oral administration.

Levodopa Adverse Effects

Nausea, vomiting, dyskinesias, postural hypotension, and dysrhythmias.

Levodopa/Carbidopa (Sinemet)

Carbidopa prevents peripheral conversion of levodopa into dopamine, increasing CNS availability and reducing peripheral side effects.

Benefits of Carbidopa

Allows lower doses of levodopa, improves CNS delivery, and decreases cardiovascular adverse effects.

"Off" Periods

Abrupt return of Parkinson's symptoms as levodopa wears off.

Pramipexole

Dopamine receptor agonist that directly stimulates dopamine receptors. Used for Parkinson's disease and Restless Legs Syndrome.

Benefits of Pramipexole

Improves motor control, lowers levodopa requirements, and reduces levodopa adverse effects.

Selegiline

Selective MAO-B inhibitor that prevents dopamine breakdown, increasing dopamine availability in the brain.

Benztropine (Cogentin)

Anticholinergic medication that blocks muscarinic receptors to reduce excessive acetylcholine activity.

Parkinson's Nursing Considerations

Monitor for orthostatic hypotension, dyskinesias, nausea, and cardiac effects. Teach patients to rise slowly, avoid high-protein meals near levodopa doses, and understand medications control symptoms but do not cure the disease.

Alzheimer's Disease (AD)

A progressive neurodegenerative disorder characterized by memory loss, cognitive decline, and impaired thinking.

Pathophysiology of Alzheimer's Disease

Degeneration of the hippocampus and cerebral cortex causes marked loss of cholinergic transmission and decreased acetylcholine.

Characteristic Pathology of Alzheimer's Disease

Beta-amyloid plaques, neuritic plaques, and neurofibrillary tangles.

Genetic Risk Factor for Alzheimer's Disease

Apolipoprotein E4 (ApoE4).

Treatment Goals for Alzheimer's Disease

Medications improve symptoms but do not cure or stop disease progression.

Major Medication Classes for Alzheimer's Disease

Cholinesterase inhibitors • NMDA receptor antagonist • Monoclonal antibodies targeting beta-amyloid plaques.

Examples of Alzheimer's Medications

Donepezil (Aricept), Rivastigmine, Galantamine, Memantine (Namenda), Aducanumab, Donanemab, and Lecanemab.

Donepezil (Aricept)

Cholinesterase inhibitor that prevents breakdown of acetylcholine, increasing cholinergic transmission.

Donepezil Adverse Effects

Cholinergic effects including nausea, vomiting, diarrhea, dizziness, and headache.

Donepezil Drug Interactions

Avoid anticholinergic medications because they oppose the therapeutic effects of donepezil.

Memantine (Namenda)

NMDA receptor antagonist used for moderate to severe Alzheimer's disease. May be used alone or with donepezil.

Advantages of Memantine

Better tolerated than cholinesterase inhibitors.

Memantine Adverse Effects

Dizziness, headache, confusion, and constipation.

Alzheimer's Nursing Considerations

Teach patients and caregivers that medications improve symptoms only, encourage medication adherence, and monitor for GI adverse effects.

Medication Comparison

Levodopa = Dopamine precursor • Carbidopa = Prevents peripheral levodopa conversion • Pramipexole = Dopamine agonist • Selegiline = MAO-B inhibitor • Benztropine = Anticholinergic • Donepezil = Cholinesterase inhibitor • Memantine = NMDA receptor antagonist.

⭐ NCLEX Must Know

Parkinson's = ↓ Dopamine + ↑ Acetylcholine • Levodopa crosses the BBB, dopamine does not • Carbidopa increases CNS levodopa and reduces peripheral effects • Avoid high-protein meals with levodopa • Pramipexole may cause sudden sleep attacks • Benztropine causes anticholinergic effects • Donepezil increases acetylcholine and should not be combined with anticholinergics • Memantine is used for moderate to severe Alzheimer's disease • Alzheimer's medications improve symptoms but do not stop progression.