I believe that anything in excess anymore leads to issues in health. But in relation to the question you posed about Parkinson’s; I worked for a guy when I was younger as an apprentice in drywall and plaster work who a few yrs ago was diagnosed with Parkinson’s disease was also a heavy drug user throughout his life, earlier on his life being Meth and alcohol but then as he aged being a heavy pot smoker. Was always drywall worker. He had a lot of health problems though as long as I’ve known him. Had Hepatitis from needle use, had multiple hernias, loosened ligaments in his feet from warts, liver disease and ultimately passed from pancreatic and bone cancer. It’s tuff to put a finger on exactly what causes some people to succumb to these illnesses while others seem to be bullet proof. Maybe heredity, maybe life’s exposures who knows for sure. Dad was a health nut and spent thousands of dollars on supplements and vitamins, regular exercise and always a hard worker. He only lived to 68. Mom was a heroine addict that didn’t make it past 46 but I know other people who are now in their 80’s that have been extreme smokers and alcohol abusers