When I was a teenager, I was somewhat of a loner; I kept to myself, rarely socialized, and was rather quiet and laconic. To some, I might have even seemed avoidant or unfriendly (although I did have a few friends with whom I would let my guard down). Unsurprisingly, I would occasionally be referred to as “antisocial” by my peers, which everyone ( including myself) generally used as a synonym for words like “aloof”, “introverted”, and “shy”.
Turns out those words are only synonymous with the colloquial definition of the word. The proper definition of antisocial (according to the Merriam-Webster dictionary) is “averse to the society of others” or “hostile or harmful to organized society”. In other words, it is used to designate disruptive or delinquent activities or entities (unorganized crime and the like, I guess).
Learning the dictionary’s definition of antisocial lead to a websearch of the term, which immediately lead me to Antisocial Personality Disorder.
ASPD is basically a mental condition where a person consistently exhibits a complete disregard for social taboos and the well-being of others. Symptoms include a lack of empathy and remorse, the manipulation of others for gain or pleasure, impulsiveness or failure to plan ahead, hostility and violent/aggressive behavior, an arrogant sense of superiority, irresponsible and deceitful behavior, and abusive relationships. Naturally, people with ASPD tend to engage in behavior such as theft, vandalism, assault, and the like. A person with ASPD will have likely been diagnosed with Conduct Disorder during childhood and early adolescence (in fact, evidence of CD is apparently required for an ASPD diagnosis).
While people who have ASPD often get called psychopaths or sociopaths, there apparently are definitive differences between these terms, although there is no reason why someone with psychopathy or sociopathy cannot have ASPD as well.
For the most part, all three conditions share similar symptoms (lack of empathy, manipulative behavior, etc.). As far as I can tell, the main difference between psychopathy and sociopathy is that the latter is the product of genetics and neurological abnormalities (part of their brain does not work) while sociopathy is apparently the result of environmental influences coupled with a possible predisposition towards antisocial behavior. Sociopathy is a somewhat informal term that used to be a synonym for psychopath, but these days is more likely to designate a non-psychopath with ASPD, which is apparently a relatively broad category in which psychopathy sits as a specific subset. At the same time, people with ASPD are defined as being unable to confirm to societal mores, whereas there are cases of people who fit the profile for psychopathy and are able to live rather normal, non-disruptive lives. Interestingly, a couple studies show that criminals with both psychopathy and ASPD tend to be worse offenders then those with just ASPD.
Psychopathy, being the result of genetic deviance, probably does not have a cure that does not involve brain surgery. There is very little information on whether or not Antisocial Personality Disorder by itself can be cured, since most people with it are not the type to seek out treatment.
There is still some debate on the differences between psychopathy and ASPD, as well as the proper numbers of people who have both or either.
What is certain is that shy, introverted people do not really fit the generally profile of someone with ASPD.
Note: ASPD is applied to someone who persistently engages in anti-social behavior, which is basically any activity that is considered (at the least) to be socially inappropriate, or that displays disregard for the well being of others. It still does not seem really applicable to quiet, background people (except from the point of view of those who consider loners to be freaks).