First of all:
We've had allusions to his past
I urge you to read the novella "The Churn" to learn more concrete facts about Amos's past, since he's one of the most intriguing characters in the series to you.
The other answer does a good job of presenting how Amos fits some of the DSM symptoms for Antisocial Personality Disorder.
Recently (February 20), a self-proclaimed autistic fan of The Expanse wrote an analysis which argues that Amos might be autistic. It’s obviously conjecture, and while it sources some authoritative sources it also sources other blog posts – for what it’s worth, though, Wes Chatham, who plays Amos on the TV show The Expanse, called the write-up "fascinating" and "very intuitive". I’ll sum it up here.
The writer points out that fictional characters can be written or "coded” as autistic, even if they're not consciously diagnosed as autistic by the authors, because they choose personality traits for the character that they’re not aware might be autistic, based on people they know but don’t know to be autistic. If we consider this a good argument, the authors might have intended Amos to be sociopathic, but instead written him as an autistic person with difficulties with empathy. Having an empathy disorder/deficiency or otherwise having sociopathic traits does not equate to being a sociopath. Autistic people may lack empathy, although not necessarily.
Children who experience early childhood traumas (like Amos has) are affected in ways that fit with Amos, and that can persist into adulthood. Amos is fairly “hypervigilant”, he is at all times aware of his surroundings and potential threats. And “disassociation” also fits well with Amos:
Disassociation or ‘zoning out’ is another way the brain and body copes with high levels of potentially toxic stress hormones for overly long periods. It can also be a learnt survival strategy, submit, switch off and wait for the frightening, painful, incomprehensible act to be over. This ability to switch off can look like defiance or non-compliance as a child may just stare ahead and not respond to requests from adults
People who experience trauma can enter a condition known as C-PTSD:
Posttraumatic stress disorder (PTSD) is a mental disorder that can develop after a person is exposed to a traumatic event, such as sexual assault, warfare, traffic collisions, or other threats on a person’s life.
Complex Post Traumatic Stress Disorder (C-PTSD) is a condition that results from chronic or long-term exposure to emotional trauma over which a victim has little or no control and from which there is little or no hope of escape, such as in cases of: domestic emotional, physical or sexual abuse.
The writer argues that Amos displays signs of Complex Post Traumatic Stress Disorder (C-PTSD) in the TV show. Examples include when Amos’s fight-or-flight instinct makes him abandon Naomi in a stressful situation. The writer points out how his autism might potentially impact his reactions:
And especially autistics are prone to notice patterns in both our individual lives and the world around us. In Amos’ mind life is only survival and there are certain patterns that are worth adhering to even tho they don’t really mesh with “civilised life” where humans have become lulled in a false sense of security.
Another argument that is put forth for Amos suffering from C-PTSD is his sexuality. Victims suffering from C-PTSD might alternate between compulsive or extremely inhibited sexuality, like Amos seems to do, and they might also self-medicate, which he definitely does. I’ll quote these three paragraphs in full from the blog post:
When reading the Churn too, one thing that really struck me is that Amos is very disconnected from his own sexuality. He knows there are physical “drives”/“needs”, but it almost reads like he dissociates his way through most of it. In the main books too, when he can’t sleep and finds it weird because he usually always sleep better after (this might be because sexual activities trigger the release of endorphin’s and other hormones that have been shown to counteract the effects of hypervigilence, thus calming ptsd symptoms to a more manageable level (it also does wonders to make you feel in control of your own situation - again, personal experience)).
Insomnia and nightmares are also common symptoms of ptsd, and it would make sense that Amos have found certain ways to alleviate these symptoms, which include his famous brothel-diving, and drinking his body weight in alcohol when he gets shore leave.Self-medication is a common behavior among people with PTSD in the community.
He’s also been described as “picking fight because he enjoys it”, which is a pretty obvious sign of self destructive behaviour, and it also circles back to his need to feel in control of his life and his surroundings. This war between self destruction and asserting control is textbook Ptsd. Coupled with growing up in an environment that is clearly mired in toxic masculinity and the heteronormative status quo (fascinating that earth society seems to have advanced absolutely not at all on those fronts, esp in Baltimore) it would seem perfectly natural for Amos to internalise his stress and emotions and keep it all under wraps until he hits port and can “blow off steam” as they say.
If Amos is indeed autistic, this research article (linked in the blog) is relevant: The Effects of Psychological Trauma on Children with Autism Spectrum Disorders
I feel the writer makes a solid argument that Amos might suffer from C-PTSD, and compelling arguments that he might have autistic traits that perhaps impact his ways of both empathizing with other people and coping with this C-PTSD.