I'm convinced that conservatives are almost all mentally ill. Most are able to function day to day, which is how they go undetected and don't access mental health services (for these issues).
Their illness is characterised by low empathy and other traits associated with 'cluster B' illnesses, probably in milder form than the ones seriously mentally ill people such as sociopaths show. However, the more seriously mentally ill such as sociopaths can be accepted within these groups due to their similarities.
People in these groups don't feel remorse or follow other human positive norms such as valuing truth, justice, kindness etc. They aren't able to understand most positive human traits and for example, when corrected would only understand that they'd been attacked and so go on the offensive and attack themselves.
They also show strong psychotic traits, which is why they will support conspiracy theories which align with their self interest with little insight.
Lack of insight is also a feature in itself, which deserves to be highlighted. There's limited capacity for growth or improvement as they don't have the innate capacity for what we would call humanity.