Parkinson disease :
Parkinson's disease causes the basal ganglia in the brain to deteriorate. As this part of the brain deteriorates, there is a reduction in a neurotransmitter called dopamine in the body. This lack of dopamine can make someone unable to move normally or balance themselves. It can also have many negative effects on sensations, thinking ability and mental health. Some symptoms of Parkinson's disease include slowed movements, stiffness, unstable posture and trembling in the body when resting. Additionally, the disease may cause an individual to blink less, drool, speak in an unusually soft tone and have an unchanging expression on the face as they lose control of their muscles. The disease also causes non motor symptoms like depression, sleeping problems and loss of smell. The condition is typically diagnosed by examining the symptoms. There is no cure for Parkinson's disease, but the symptoms can be managed with medicines and treatments like deep brain stimulation.