Not Medical Advice: Yes, it's bad as nicotine is an excitatory neurotransmitter that enhances glutamate release. Glutamate plays a role in both epilepsy and ALS.
It can also cause damage to gum tissue and even loss of teeth. It also reduces a person's ability to taste and smell. And most importantly, smokeless tobacco contains cancer causing-chemicals that can lead to cancers of the mouth, pharynx, larynx, and esophagus.
Smokeless tobacco still has nicotine content (varies with commercial brand, ranges from 1.22% for chewing tobacco to 2.58% for moist snuff). Too much nicotine may cause seizure or may aggravate epilepsy.
According to Reuters, young smokers who have smoked more cigarettes have clear differences in their brains compared to lighter smokers, according to a new study. Find out more here.