- **Definition**: A group of mental health conditions characterized by enduring patterns of behavior, cognition, and inner experience that deviate from cultural expectations. - **Types**: Borderline personality disorder, narcissistic personality disorder, antisocial personality disorder, and avoidant personality disorder. - **Symptoms**: Vary widely but may include difficulties in relationships, self-image issues, and emotional instability. - **Treatment**: [[Psychotherapy]] (dialectical behavior therapy, cognitive-behavioral therapy) and medications for co-occurring symptoms.