Parkinson's is a progressive degenerative disorder in which neurons are affected in basal ganglia and substantia nigra of brain. These neurons are responsible for producing dopamine transmitter and in Parkinson's they start to die.
Loss of around 80% of dopamine results in the symptoms like Bradykinesia (slow movement, decreased blinking, drooling), stiffness, tremor, balance problem etc. Treatment is done by medication, brain stimulation surgery, exercise and diet.
A negative correlation is most clearly seen between different levels of female education and the total fertility rate (TFR) in a population. TFR is the number of children a woman can expect to have over her lifetime given current rates of age-specific fertility.