- Parkinson’s disease (PD) is a progressive neurodegenerative disorder that primarily affects movement, although it can also cause a wide range of non-motor symptoms. It is the second most common neurodegenerative disease after Alzheimer’s and predominantly affects individuals over the age of 60, though early-onset forms also occur. The hallmark of PD is the loss of dopaminergic neurons in the substantia nigra pars compacta, a region of the midbrain involved in regulating motor control. This dopamine deficiency leads to the characteristic motor symptoms of the disease.
- The cardinal motor symptoms of Parkinson’s disease include bradykinesia (slowness of movement), resting tremor, muscle rigidity, and postural instability. These symptoms often begin asymmetrically, typically starting on one side of the body. Over time, they may progress to affect both sides and become increasingly disabling. As the disease advances, patients often develop a shuffling gait, masked facial expressions, reduced arm swing, and speech difficulties. In later stages, freezing of gait and falls become more frequent.
- In addition to motor symptoms, PD includes a spectrum of non-motor symptoms that may precede or accompany movement problems. These include sleep disturbances, constipation, depression, anxiety, cognitive decline, fatigue, loss of smell (anosmia), and autonomic dysfunction (e.g., orthostatic hypotension and urinary urgency). The non-motor aspects of PD can significantly impact quality of life and may even be more disabling than motor symptoms in some individuals.
- The underlying pathology of Parkinson’s disease involves the accumulation of alpha-synuclein, a presynaptic neuronal protein that forms insoluble aggregates known as Lewy bodies within neurons. These aggregates are thought to contribute to cellular dysfunction and neurodegeneration. While the cause of PD is not fully understood, it is believed to result from a combination of genetic predispositions (mutations in genes like LRRK2, PINK1, PARK7, and SNCA) and environmental exposures (such as pesticides, heavy metals, and head trauma).
- Diagnosis of Parkinson’s disease is primarily clinical, based on the presence of motor symptoms and their response to dopaminergic therapy (typically levodopa). There is no definitive laboratory or imaging test for PD, though brain imaging (e.g., DaTscan) can help rule out other disorders and support diagnosis in uncertain cases.
- Treatment of Parkinson’s disease is symptomatic, with levodopa being the most effective medication for motor symptom control. It is often combined with carbidopa to enhance central availability and reduce side effects. Other medications include dopamine agonists, MAO-B inhibitors, and COMT inhibitors, which can be used in combination or as alternatives to levodopa in early or advanced stages. Over time, long-term levodopa therapy can lead to motor fluctuations and dyskinesias (involuntary movements), requiring careful medication adjustments. For advanced cases, deep brain stimulation (DBS) may be considered to alleviate motor symptoms.
- There is currently no cure for Parkinson’s disease, and no available therapy has been conclusively shown to slow its progression. Ongoing research is exploring neuroprotective agents, gene therapy, stem cell therapy, and strategies to clear alpha-synuclein aggregates. In addition, multidisciplinary care—including physical therapy, occupational therapy, speech therapy, and nutritional support—is crucial in maintaining function and quality of life.
