Parkinson's disease - Wikipedia

Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system.[1] As the disease worsens, non-motor symptoms become more common.[1][4] The symptoms usually emerge slowly.[1] Early in the disease, the most obvious symptoms are shaking, rigidity, slowness of movement, and difficulty with walking.[1] Thinking and behavioral problems may also occur.[2] Dementia becomes common in the advanced stages of the disease.[2] Depression and anxiety are also common, occurring in more than a third of people with PD.[2] Other symptoms include sensory, sleep, and emotional problems.[1][2] The main motor symptoms are collectively called "parkinsonism", or a "parkinsonian syndrome".[4][9]

The cause of Parkinson's disease is unknown, but is believed to involve both genetic and environmental factors.[4] Those with a family member affected are more likely to get the disease themselves.[4] There is also an increased risk in people exposed to certain pesticides and among those who have had prior head injuries, while there is a reduced risk in tobacco smokers and those who drink coffee or tea.[4][10] The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain.[1] This results in not enough dopamine in this region of the brain.[1] The cause of this cell death is poorly understood, but it involves the build-up of proteins into Lewy bodies in the neurons.[4] Diagnosis of typical cases is mainly based on symptoms, with tests such as neuroimaging used to rule out other diseases.[1]

There is no cure for Parkinson's disease.[1] Treatment aims to improve the symptoms.[1][11] Initial treatment is typically with the antiparkinson medication levodopa (L-DOPA), followed by dopamine agonists when levodopa becomes less effective.[2] As the disease progresses and neurons continue to be lost, these medications become less effective while at the same time they produce a complication marked by involuntary writhing movements.[2] Diet and some forms of rehabilitation have shown some effectiveness at improving symptoms.[12][13] Surgery to place microelectrodes for deep brain stimulation has been used to reduce motor symptoms in severe cases where drugs are ineffective.[1] Evidence for treatments for the non-movement-related symptoms of PD, such as sleep disturbances and emotional problems, is less strong.[4]