Parkinson's disease

Parkinson's disease is a progressive disorder of the brain caused by the gradual loss of nerve cells in a region that produces dopamine, a chemical messenger essential for smooth, controlled movement. As dopamine falls, the classic motor features emerge: a tremor that is most noticeable at rest (often starting in one hand), slowness of movement (bradykinesia), muscle stiffness, and, later, problems with balance and posture. Handwriting may shrink, the face becomes less expressive, and walking becomes shuffling with reduced arm swing. Many people also have non-motor symptoms — reduced sense of smell, constipation, disturbed sleep, mood changes and, in later disease, memory and thinking difficulties. It usually begins after age 60 and progresses slowly over many years. The diagnosis is clinical, made by a neurologist from the pattern of symptoms and examination; there is no blood test for it, and lab tests mainly serve to exclude conditions that can mimic it (such as low vitamin B12, thyroid problems, or medication side effects). While there is no cure, treatments that replace or mimic dopamine (such as levodopa) can control symptoms effectively, often for years, and are tailored over time.

• No blood test diagnoses Parkinson's — it is a clinical diagnosis made by a neurologist.
• Vitamin B12 — checked to exclude a treatable mimic and because deficiency worsens neurological symptoms.
• TSH (thyroid) — an underactive thyroid can cause slowness that mimics parkinsonism.
• Vitamin D — often checked given falls and bone-health concerns.
• Copper / caeruloplasmin — in younger patients, to exclude Wilson's disease as a rare mimic.

• A tremor, most noticeable at rest, often starting in one hand
• Slowness of movement (things take longer)
• Muscle stiffness
• Reduced arm swing and a shuffling walk
• Smaller handwriting and a less expressive face
• Problems with balance, in later disease
• Non-motor: reduced smell, constipation, sleep and mood changes