This study looked a the amount of caffeine consumed and the age when consumption started, in both Sweden and the US.
"There was a consistently higher risk of MS among those who drank fewer cups of coffee every day in both studies, even after adjusting for factors such as smoking and weight during adolescence."
"Their findings support those of previous animal studies of MS, and they strengthen existing evidence that caffeine protects against neurodegenerative diseases such as Alzheimer's and Parkinson's disease."
It actually reports that "six cups a day is linked to 31% lower risk in MS". Six cups! A quick google shows that more than 4 cups of coffee a day can cause stomach problems, insomnia, fast heart beat, muscle tremors, anxiety. I'm not supporting that any of this is proven, but just that I usually like to follow more of the "everything in moderation" guide. However, like this article suggests, the role of coffee as a neuroprotectant certainly warrants further investigation.