Parkinson’s erodes dopamine cells that start and smooth movement
Parkinson’s disease slowly destroys dopamine-making neurons in the substantia nigra, producing tremor, rigidity, slowed starts, and unstable posture—parkinsonism. It usually appears after sixty, hitting about one percent of that age group. No cure exists; drugs buy time and then complicate it.
Causes mix genes and environment attacking cellular processes; abnormal alpha-synuclein aggregates classify it as a synucleinopathy affecting central and peripheral nerves. Diagnosis rests mainly on neurological motor signs; PET imaging can support. Cases beginning before fifty are labelled early-onset Parkinson's. Misfolded alpha-synuclein that cells fail to clear clumps into Lewy bodies, and the build-up prompts microglia to release inflammatory molecules; if that response turns chronic, it deepens nerve damage and disturbs metabolism.
First-line medicines include levodopa, MAO-B inhibitors, or dopamine agonists. Later they weaken and may spark involuntary movements. Diet and rehab help function. About thirty percent progress to Parkinson’s disease dementia; tremor shows in roughly seventy to seventy-five percent, often at rest. When pills no longer control severe motor symptoms, deep brain stimulation is an option. Evidence is thin for treating non-motor problems such as poor sleep and mood swings. Life expectancy is close to normal, though shorter for early-onset cases. The dementia that develops counts, with dementia with Lewy bodies, as one of two forms of Lewy body dementia.
Parkinsonism is not exclusive to PD—HIV and some drugs can mimic the motor cluster; related neurodegenerative conditions with distinct features are grouped as Parkinson-plus syndromes, or atypical parkinsonian disorders.
Movement is only part of the picture. Failures of the autonomic nervous system, disturbed sleep, a fading sense of smell, anxiety, psychosis and cognitive decline can surface at any stage, and these non-motor troubles grow more common as the illness advances. Tremor, the most visible sign, most often appears at rest, but it can also strike during deliberate movement or while trying to hold an upright posture.
Source: Parkinson's disease
