Three stories lead to this question.
The least of these is the story that Romney strapped his dog to the roof of his car for a vacation trip. Certainly it shows a level of cruelty to an animal that most people find disturbing. Worse is the fact the dog was so terrified it shit itself and Romney just "hosed down" the dog and put it back in its torture chamber. Worst of all is the insane claim that the dog "loved it." Cruelty to animals, insensitive to suffering, insists the victim enjoyed the suffering - three major symptoms of a sociopath.
The second story comes from when he was in boarding school and criminally assaulted a fellow student. Organizing a gang to attack a younger student - clearly the act of a bully - shows the ability to manipulate others. He showed a desire to dominate and humiliate another. Ignoring the cries for help is cruelty to humans. There was a total lack of remorse to the point he claims to not even remember the event. So this incident has four major symptoms of a sociopath.
The third story is about how Romney liked to dress up like a policeman and pretend to be a cop. His "pranks" were to frighten and intimidate people. He would "arrest" women and abandon them without a car. His felonies include impersonating a law enforcement officer and kidnapping. Worst, however, is the creepiness factor. Serial killers and serial rapists like to impersonate policemen. That Romney chose this path for his recreation shows him to be a deeply disturbed individual.
We can add his joy at firing people, the pain he inflicted during his Bain Capital days, and his treatment of his neighbors as criminals to find an adult with a mile wide callousness streak. But does that make him a sociopath?
Of the traits of the sociopath listed here, Mitt Romney displays most of them. He is glib, manipulative, has a grandiose sense of self, and lacks remorse. He is emotionally shallow (robotic) and incapable of common empathy. He was a juvenile delinquent who got away with it because of his family connections. He is authoritarian, secretive, and paranoid. And he really does want to rule the world and will spend a billion dollars to do it.
The answer, I'm afraid, is yes. Mitt Romney is a sociopath and the dangers of electing one to the presidency cannot be overstated.