I knew a woman who grew up in Ulster County, New York in the 1950s. There are many apple orchards in the area surrounding her neighborhood which were treated with various pesticides. Her mother died of Parkinson’s, as she did, as her younger brother did, and as quite a few of her high school friends have. I am not aware of any studies that connect this apparent cluster to the pesticides, but I cannot put it down to mere coincidence.
We used to ride our bikes in the DDT cloud behind the fogger truck, just to watch the mosquitos drop dead around us.
That being said, there are a lot of organophosphate bug killers, and they do affect mammal nerves.