What would be the most common causes and solutions to 'personality disorder'?

Complicated: Personality disorders are often caused by disruptions in formative relationships and life events, and can be highly disruptive to adult relationships and functioning. Medication does not cure the underlying disorder, which often requires long-term counseling, although individuals with personality disorders are less likely to engage in and stick with that needed treatment.

Good question: There is no way to "prevent" personality disorders. They are part of the way the brain is biologically wired and programmed to function. Genetics and life events play a big role. People with personality disorders tend to be cruel and selfish. Their friends and relatives usually need and seek counseling, to learn how to deal with the emotional pain inflicted by them.

Personality disorder: Biopsychosocial, to include genetics and self concept and events or experiences. Treatment is psychotherapy.