The teen's recurrent intrusive thoughts (obsessions) and repetitive handwashing behaviors (compulsions) performed to reduce distress are hallmark features of Obsessive-Compulsive Disorder. OCD is characterized by obsessions that cause anxiety and compulsions that temporarily relieve that anxiety, creating a reinforcing cycle. The two-month duration and the specific pattern of intrusive thoughts leading to ritualistic behaviors distinguish this from Generalized Anxiety Disorder, which involves excessive worry without compulsions. Specific phobias involve fear of particular objects/situations without intrusive thoughts, and Major Depressive Disorder's psychomotor symptoms are different from anxiety-driven compulsions. OCD was moved out of the Anxiety Disorders category in DSM-5 to its own category: Obsessive-Compulsive and Related Disorders.

This describes Disruptive Mood Dysregulation Disorder (DMDD), characterized by severe recurrent temper outbursts (verbal or behavioral) that are grossly out of proportion to the situation, occurring three or more times per week for at least 12 months with no more than three consecutive months without symptoms. The mood between outbursts is persistently irritable or angry most of the day, nearly every day. Onset must be before age 10. ODD involves defiance and vindictiveness but not necessarily the severe recurrent outbursts with chronic irritability. Bipolar I requires discrete manic episodes with elevated mood and increased activity; chronic irritability alone isn't sufficient. Intermittent Explosive Disorder doesn't typically involve persistent irritable mood between episodes in children.

This describes Generalized Anxiety Disorder (GAD), characterized by excessive anxiety and worry about multiple events or activities occurring more days than not for at least six months. The worry is difficult to control and associated with at least three additional symptoms (restlessness, fatigue, concentration problems, irritability, muscle tension, sleep disturbance). The key features are the generalized nature across multiple domains, chronicity (six months), and associated physical/cognitive symptoms. Panic Disorder involves discrete panic attacks and worry about future attacks. OCD involves specific obsessions and compulsions. PTSD requires trauma exposure and specific trauma-related symptom clusters including intrusion and avoidance symptoms.

This describes Antisocial Personality Disorder, which requires a pervasive pattern of disregard for and violation of others' rights occurring since age 15, evidence of Conduct Disorder before age 15, and the individual must be at least 18 years old. Key features include repeated unlawful acts, deceitfulness, impulsivity, irritability and aggressiveness, disregard for safety, consistent irresponsibility, and lack of remorse. The pattern must be pervasive and longstanding, not limited to discrete episodes. Narcissistic Personality Disorder involves grandiosity but not necessarily criminal behavior or lack of remorse. Borderline Personality Disorder involves emotional instability and abandonment fears. Intermittent Explosive Disorder involves discrete aggressive outbursts, not a pervasive pattern of rights violations.

This case presents classic symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD), Combined Presentation. The key diagnostic features include persistent inattention and hyperactivity occurring across multiple settings (both home and school) for at least 6 months, causing functional impairment in academic performance. ADHD requires symptoms to be present before age 12 and to interfere with functioning in two or more settings. While Oppositional Defiant Disorder involves defiant behavior, it lacks the core attention and hyperactivity symptoms. Autism Spectrum Disorder is characterized by social-communication deficits and repetitive behaviors rather than hyperactivity as the primary concern. Generalized Anxiety Disorder may include concentration difficulties but does not feature the pervasive hyperactivity across settings that defines ADHD.

This describes Tourette's Disorder, which requires both multiple motor tics and one or more vocal tics present at some time during the illness, occurring many times a day nearly every day or intermittently for more than one year, with onset before age 18. Tics are sudden, rapid, recurrent, nonrhythmic motor movements or vocalizations. The combination of multiple motor tics AND vocal tics persisting over one year distinguishes Tourette's from other tic disorders. Persistent Motor Tic Disorder involves only motor tics without vocal tics. Stereotypic Movement Disorder involves repetitive nonfunctional movements that are more rhythmic and purposeless than tics. OCD involves obsessions and compulsions, not involuntary tics.

This case describes Anorexia Nervosa, which has three core features: restriction of energy intake leading to significantly low body weight, intense fear of gaining weight or becoming fat (or persistent behavior that interferes with weight gain), and disturbance in the way body weight or shape is experienced. The persistent belief of being severely overweight despite being underweight demonstrates the required body image disturbance. Bulimia Nervosa involves binge eating with compensatory behaviors and typically occurs at normal or above-normal weight. Binge-Eating Disorder involves recurrent binges without restriction leading to low weight. ARFID involves food restriction but without the body image disturbance or fear of weight gain.

Limited eye contact, difficulties with social reciprocity, and repetitive behaviors beginning in early development are core features of Autism Spectrum Disorder, which falls under Neurodevelopmental Disorders. ASD is characterized by persistent deficits in social communication and social interaction across contexts, plus restricted, repetitive patterns of behavior, interests, or activities, with symptoms present in early developmental period. Personality Disorders don't typically begin until adolescence or early adulthood. Anxiety Disorders might cause social avoidance but don't include the developmental social-communication deficits or repetitive behaviors. Disruptive disorders focus on aggression and rule-breaking rather than social-communication differences.

This presentation clearly describes a manic episode characteristic of Bipolar I Disorder. The patient exhibits the classic triad of mania: elevated mood, decreased need for sleep, and grandiosity, along with risky behavior (excessive spending) severe enough to require hospitalization. A single manic episode lasting at least one week (or any duration if hospitalization is required) is sufficient for a Bipolar I diagnosis. Cyclothymic Disorder involves milder hypomanic symptoms without full manic episodes or hospitalization. Major Depressive Disorder involves depressed mood and anhedonia, not the elevated mood and grandiosity seen here. Schizoaffective Disorder requires both mood episodes and psychotic symptoms that occur independently of mood episodes, which is not described in this case.

Multiple distinct identity states (previously called personalities) combined with recurrent gaps in recall for everyday events are the two required features for Dissociative Identity Disorder (DID). This disorder involves disruption of identity characterized by two or more distinct personality states, with recurrent gaps in recall that are inconsistent with ordinary forgetting. Depersonalization/Derealization Disorder involves feelings of detachment or unreality but maintains a single, intact identity. Schizophrenia might involve identity confusion but centers on psychotic symptoms like hallucinations and delusions. Delusional Disorder involves fixed false beliefs without the identity fragmentation seen in DID.