Psychological disorders are defined by the American Psychiatric Association (APA) through four main criteria: significant disturbances in thoughts, feelings, or behaviors; underlying biological, psychological, or developmental dysfunction; resultant distress or disability; and a lack of culturally approved responses.Schizotypal individuals exhibit eccentric behaviors and suspiciousness.The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) serves as the authoritative classification system, outlining disorders, diagnostic features, symptoms, prevalence, risk factors, and comorbidity.Genetic vulnerability combined with environmental stress is essential for the development of schizophrenia, alongside the dopamine hypothesis, which posits that excess dopamine contributes to the disorder.Obsessive-Compulsive Disorder (OCD) involves intrusive and unwanted thoughts (obsessions) and a compulsion to perform repetitive actions or mental tasks.Major Depressive Disorder is marked by persistent sadness or diminished interest in activities, alongside weight changes, sleep issues, fatigue, feelings of guilt or worthlessness, and suicidal thoughts.Seasonal affective disorder manifests as major depressive symptoms tied to specific seasons, while peripartum onset, or postpartum depression, affects women during pregnancy or shortly postpartum.Bipolar disorder showcases mood swings between depression and mania, where manic episodes involve euphoric moods and increased activity.Individuals with panic disorder experience recurrent panic attacks and persistent concern about their recurrence, while generalized anxiety disorder entails ongoing anxiety without a specific trigger.Personality disorders fall into three clusters: Cluster A (odd or eccentric personalities), Cluster B (impulsive and erratic behaviors), and Cluster C (nervous and fearful traits).Body Dysmorphic Disorder centers on an obsessive concern over perceived physical flaws, prompting repetitive behaviors related to appearance.Post-Traumatic Stress Disorder (PTSD) arises from experiencing a traumatic event, leading to symptoms such as intrusive memories, avoidance of reminders, negative emotions, and hypervigilance.Persistent depressive disorder involves chronic sadness without fulfilling major depression criteria.Abnormal brain activity in emotional regulation areas, such as the amygdala, is linked to depression, exacerbated by stress-related cortisol increases.The biological perspective links them to genetic factors, chemical imbalances, and brain abnormalities, while the psychosocial perspective highlights the role of learning, stress, and environmental influences.Generalized Anxiety Disorder (GAD) is defined by a persistent state of uncontrolled and excessive worry.In contrast, Hoarding Disorder manifests as the inability to discard possessions, regardless of their actual worth.Key symptoms of schizophrenia include hallucinations, delusions, disorganized thinking, lack of motivation, expressionless face, reduced speech, and diminished social engagement.Factors during pregnancy, such as obstetric complications and maternal stress, and marijuana use, are implicated in the disorder's onset.There are varying perspectives on psychological disorders.