Parkinsonism Overview

Parkinson's disease (PD) is a progressive neurodegenerative disorder primarily impacting older individuals.

PD is characterized by rigidity, tremor, slowed movement (bradykinesia), and postural instability.

The most significant lesion in PD is the degeneration of neurons in the substantia nigra pars compacta (SN-PC) and the nigrostriatal (dopaminergic) tract.

Levodopa is a precursor to dopamine and is used to treat Parkinson's disease by increasing dopamine levels in the brain.

Drug-induced parkinsonism can occur as a side effect of certain medications like neuroleptics (antipsychotics) and metoclopramide (anti-nausea).

Reserpine, a drug that depletes dopamine, was historically used. It provides insight into the role of dopamine in Parkinson's.

Excess glutamate can lead to 'excitotoxic' neuronal death in Parkinson's, causing a cascade of events that damage brain cells.

Wilson's disease is a rare cause of Parkinsonism due to copper accumulation in the brain.

Drugs that activate dopamine receptors to help manage symptoms of Parkinson's disease.

A type of dopamine agonist that is longer-acting and may contribute less to dopaminergic neuronal damage compared to levodopa.

A type of dopamine agonist that is approved for Parkinson's disease and Restless Legs Syndrome.

A common enzyme found in the body that breaks down dopamine.

A drug that inhibits the action of MAO-B, leading to a higher concentration of dopamine in the brain.

A naturally occurring enzyme that helps break down dopamine.

A protein that binds to drugs, influencing how long the drug stays in the body.

The time it takes for the drug concentration in the body to reduce by half.

These drugs are used to treat Parkinson's disease by increasing dopamine levels. They work by inhibiting the enzyme that breaks down dopamine, MAO-B.

These medications help to reduce the breakdown of dopamine by inhibiting the enzyme COMT.

Amantadine acts as a dopamine facilitator by blocking the NMDA receptor, which is involved in glutamate signaling. This indirectly enhances dopamine release.

These drugs are used to treat Parkinson's disease by blocking the action of acetylcholine in the brain. This helps to improve movement control.

These drugs are often used as an alternative to central anticholinergics for treating Parkinson's disease. They also block acetylcholine.

It is a precursor to dopamine, meaning it's converted into dopamine in the body. It helps to increase dopamine levels, relieving symptoms of Parkinson's disease.

They are a family of dopamine receptors, responsible for receiving dopamine signals. They play a crucial role in movement, motivation, and pleasure.

These are different types of dopamine receptors. D1-like receptors (D1, D5) increase cellular activity, while D2-like receptors (D2, D3, D4) decrease cellular activity.

A serious side effect of levodopa treatment characterized by involuntary movements that can be as disabling as Parkinson's disease itself.

The tendency for levodopa's effectiveness to fluctuate over time, leading to periods of good control followed by periods of worsening symptoms.

A specific type of fluctuation where Parkinson's symptoms worsen just before the next dose of levodopa is due.

A type of fluctuation where the patient experiences extreme swings between periods of good control and complete lack of control.

A severe form of fluctuation where a patient experiences only two states, either completely functional or completely disabled.

Levodopa's effectiveness is reduced because it competes with dopamine for entry into synaptic vesicles, essentially blocking dopamine's action.

Levodopa is broken down in the periphery (outside the brain), reducing its effectiveness.

Antihypertensive drugs can worsen the postural hypotension side effect of levodopa.

The basal ganglia is a group of interconnected brain structures involved in motor control, learning, and cognitive function. Its modulatory loop helps refine motor output, ensuring smooth muscle movement and reducing unnecessary tension.

Parkinson's disease is a neurodegenerative disorder characterized by the loss of dopamine-producing neurons in the substantia nigra. This loss leads to an imbalance in neurotransmitters in the basal ganglia, causing symptoms like tremors, rigidity, and slow movements.

Levodopa is a precursor to dopamine that is used to treat Parkinson's disease. It crosses the blood-brain barrier and is converted to dopamine in the brain, helping to restore balance in the basal ganglia.

Levodopa's absorption and availability are affected by factors like gastric emptying and competition with other amino acids for the same carrier protein. A slow gastric emptying time means more levodopa is exposed to degradation in the gut and liver, reducing its bioavailability.

Levodopa can cause side effects like nausea and vomiting due to its rapid absorption and high first-pass metabolism. Starting with a low dose and gradually increasing it can help to minimize these side effects.

Dopamine plays a role in regulating the release of prolactin and growth hormone. In Parkinson's patients on levodopa therapy, prolactin levels decrease, but growth hormone levels may not increase as expected, suggesting altered regulation of hormone secretion.

A common side effect of selegiline when it interacts with certain drugs.

A newer MAO-B inhibitor that is more potent and longer-lasting than selegiline.

A common side effect of COMT inhibitors.

A potential risk associated with tolcapone, a COMT inhibitor.

A drug used to treat Parkinson's disease that acts as a glutamate antagonist.