ADHD subtypes and diagnostic criteria US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for ADHD subtypes and diagnostic criteria. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
ADHD subtypes and diagnostic criteria US Medical PG Question 1: A mother brings her 3-year-old son to the doctor because she is worried that he might be harming himself by constantly banging his head on the wall. He has been exhibiting this behavior for a few months. She is also worried because he has started to speak less than he used to and does not respond when his name is called. He seems aloof during playtime with other children and seems to have lost interest in most of his toys. What is the most likely diagnosis?
- A. Autism spectrum disorder (Correct Answer)
- B. Attention deficit hyperactivity disorder
- C. Generalized anxiety disorder
- D. Bipolar disorder
- E. Obsessive-compulsive disorder
ADHD subtypes and diagnostic criteria Explanation: ***Autism spectrum disorder***
- The child's symptoms of **head banging** (a repetitive, self-stimulatory behavior), **decreased speech**, **lack of response to his name**, **social aloofness**, and **loss of interest in toys** are classic indicators of **Autism Spectrum Disorder (ASD)**.
- ASD involves persistent deficits in **social communication and interaction** across multiple contexts, as well as **restricted, repetitive patterns of behavior, interests, or activities**.
*Attention deficit hyperactivity disorder*
- **ADHD** is characterized primarily by **inattention, hyperactivity, and impulsivity**, which are not the prominent or primary concerns described in this case.
- While children with ADHD may have social difficulties, their core symptoms do not typically include severe **social aloofness, communication regression**, or **self-injurious repetitive behaviors** like head banging.
*Generalized anxiety disorder*
- **Generalized anxiety disorder (GAD)** in children typically presents with excessive worry about multiple events or activities, often accompanied by **physical symptoms of anxiety** such as restlessness, fatigue, and difficulty concentrating.
- It does not explain the **communication regression, social deficits**, or **stereotypical behaviors** like head banging observed in this child.
*Bipolar disorder*
- **Bipolar disorder** in children often manifests with severe mood dysregulation, including distinct periods of **elevated or irritable mood (mania/hypomania)** and depression.
- The symptoms described, such as social withdrawal and communication difficulties, are not characteristic of the primary presentations of bipolar disorder.
*Obsessive-compulsive disorder*
- **OCD** is characterized by the presence of **obsessions (recurrent, persistent thoughts, urges, or images)** and/or **compulsions (repetitive behaviors or mental acts)**.
- While head banging can be a repetitive behavior, the broader constellation of symptoms, including social and communication deficits, is not typical of primary OCD in young children.
ADHD subtypes and diagnostic criteria US Medical PG Question 2: A 20-year-old female presents to student health at her university for excessive daytime sleepiness. She states that her sleepiness has caused her to fall asleep in all of her classes for the last semester, and that her grades are suffering as a result. She states that she normally gets 7 hours of sleep per night, and notes that when she falls asleep during the day, she immediately starts having dreams. She denies any cataplexy. A polysomnogram and a multiple sleep latency test rule out obstructive sleep apnea and confirm her diagnosis. She is started on a daytime medication that acts both by direct neurotransmitter release and reuptake inhibition. What other condition can this medication be used to treat?
- A. Obsessive-compulsive disorder
- B. Bulimia
- C. Attention-deficit hyperactivity disorder (Correct Answer)
- D. Tourette syndrome
- E. Alcohol withdrawal
ADHD subtypes and diagnostic criteria Explanation: ***Attention-deficit hyperactivity disorder***
- The patient's presentation is consistent with **narcolepsy type 2 (without cataplexy)**, given the excessive daytime sleepiness, short latency to REM sleep (immediate dreaming), and exclusion of sleep apnea. The medication described, acting via **direct neurotransmitter release and reuptake inhibition**, is characteristic of a stimulant like **methylphenidate** or an amphetamine-based drug.
- These stimulants are commonly used as first-line treatment for **attention-deficit hyperactivity disorder (ADHD)** due to their effects on dopamine and norepinephrine in the brain, improving focus and reducing impulsivity.
*Obsessive-compulsive disorder*
- **Obsessive-compulsive disorder (OCD)** is typically treated with selective serotonin reuptake inhibitors (SSRIs) or cognitive behavioral therapy.
- Stimulants are not indicated for OCD and may even worsen anxiety symptoms in some individuals.
*Bulimia*
- **Bulimia nervosa** is often managed with a combination of psychotherapy (e.g., cognitive behavioral therapy) and antidepressants like fluoxetine.
- Stimulants are not a primary treatment for bulimia and could potentially exacerbate some symptoms or risks due to their appetite-suppressing effects.
*Tourette syndrome*
- **Tourette syndrome** involves motor and vocal tics and is often treated with alpha-2 adrenergic agonists (e.g., guanfacine, clonidine) or dopamine receptor blocking agents.
- Stimulants generally are not used for Tourette syndrome as they can sometimes worsen tics.
*Alcohol withdrawal*
- **Alcohol withdrawal** is a medical emergency managed with benzodiazepines to prevent seizures and delirium tremens.
- Stimulants are contraindicated in alcohol withdrawal as they can increase seizure risk and cardiac complications.
ADHD subtypes and diagnostic criteria US Medical PG Question 3: A 15-year-old girl is brought into her pediatrician's office by her mother because the mother thinks her daughter has attention issues. The mother explains that her daughter started high school four months ago and had lackluster grades in a recent progress report despite having earned consistent top marks in middle school. The mother complains that her daughter never talks to her at home anymore. The patient yells at her mother in the exam room, and the mother is escorted out of the room. The patient scoffs that her mother is so overbearing, ruining her good days with criticism. She begins to chew gum and states that she hates hanging out with the girls on the cheerleading squad. She denies experiencing physical abuse from anyone or having a sexual partner. She has seen kids smoke marijuana underneath the football field bleachers, but does not go near them and denies smoking cigarettes. She denies any intention to harm herself or others, thinks her grades went down because her teachers are not as good as her middle school teachers, and states she thinks she learns best by watching explanations through online videos. What is the most likely diagnosis?
- A. Attention deficit hyperactivity disorder
- B. Conduct disorder
- C. Oppositional defiant disorder
- D. Antisocial personality disorder
- E. Normal behavior (Correct Answer)
ADHD subtypes and diagnostic criteria Explanation: ***Normal behavior***
- The patient exhibits behaviors typical of **adolescent development**, including increased desire for independence, conflicts with parents, and shifting social interests.
- While academic performance has declined, her explanation about learning preferences and criticisms of school staff is consistent with a normal rebellious phase and does not indicate a mental health disorder.
*Attention deficit hyperactivity disorder*
- ADHD is characterized by persistent patterns of **inattention**, **hyperactivity**, and **impulsivity** that interfere with functioning or development.
- The patient's explanation for poor grades and lack of other ADHD symptoms makes this diagnosis less likely; her academic decline is recent and attributed to external factors.
*Conduct disorder*
- Conduct disorder involves a repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate societal norms or rules are violated, such as **aggression to people and animals**, **destruction of property**, **deceitfulness or theft**, or **serious violation of rules**.
- The patient's behaviors, while defiant, do not meet criteria for significant rule-breaking, aggression, or deceit.
*Oppositional defiant disorder*
- This disorder involves a pattern of **angry/irritable mood**, **argumentative/defiant behavior**, or **vindictiveness** lasting at least 6 months, often directed at an authority figure.
- While the patient shows some defiant behavior towards her mother, it is limited to this particular interaction, and not a pervasive pattern that meets the frequency and severity for ODD, especially considering her age and developmental stage.
*Antisocial personality disorder*
- Antisocial personality disorder cannot be diagnosed before age 18 and requires a history of **conduct disorder** symptoms before age 15.
- The patient does not display the pervasive disregard for the rights of others, deceit, or criminal behavior characteristic of antisocial personality disorder.
ADHD subtypes and diagnostic criteria US Medical PG Question 4: A 14-year-old boy is brought to a child psychiatry office by his father, who is concerned about his grades and teachers’ comments that he has “problems focusing.” He has a B- average. The boy's teachers in math, social studies, and English say that he often appears to not be listening in class, instead talking to classmates, making jokes, and blurting out incorrect answers. He typically turns in his homework late or not at all. During other classes (band and science, which he enjoys), none of these behaviors are observed. At home, he enjoys playing chess and reads comic and fiction books for hours without pause. His father describes him as calm and organized at home. Formal testing reveals an intelligence quotient (IQ) of 102. Which of the following is the most likely explanation for this patient’s grades?
- A. Mood disorder
- B. Attention deficit hyperactivity disorder (ADHD)
- C. Absence seizures
- D. Intellectual disability
- E. Specific Learning Disorder (Correct Answer)
ADHD subtypes and diagnostic criteria Explanation: ***Specific Learning Disorder***
- This patient demonstrates **selective academic difficulties** in math, social studies, and English, while performing well in band and science (subjects he enjoys).
- The key feature is that his problems are **context-dependent and motivation-based** rather than representing a true learning disorder, but among the given options, this is the most fitting explanation for his grades.
- His **normal IQ (102)** and ability to focus for extended periods on preferred activities (chess, reading) suggest this is more likely **underachievement due to lack of interest** rather than a true pathological condition.
- True specific learning disorders typically show persistent difficulties in specific academic skills regardless of interest level, making this diagnosis imperfect but the best option available.
*Intellectual disability*
- A diagnosis of intellectual disability requires an **IQ below 70-75**, which is not present here as the patient's IQ is 102 (normal range).
- Additionally, significant deficits in **adaptive functioning across multiple domains** (conceptual, social, practical) during the developmental period are necessary for diagnosis.
- This patient shows **normal functioning at home** and in preferred activities, ruling out intellectual disability.
*Mood disorder*
- While mood disorders can affect concentration and academic performance, the patient's **selective inattentiveness** (present only in certain classes) and ability to focus for hours on enjoyable activities make this unlikely.
- There are **no reported symptoms** of depression (persistent sadness, anhedonia, sleep/appetite changes) or mania (elevated mood, grandiosity, decreased need for sleep).
*Attention deficit hyperactivity disorder (ADHD)*
- ADHD symptoms are typically **pervasive across settings** and are not dependent on whether the activity is enjoyable.
- The patient's ability to **focus for hours on chess and reading**, and his calm, organized behavior at home, **contradict the diagnostic criteria** for ADHD.
- ADHD requires significant impairment in multiple domains, which is not observed here.
*Absence seizures*
- Absence seizures are characterized by **brief episodes of staring spells** with impaired consciousness, typically lasting only seconds.
- These episodes involve **sudden cessation of activity** and are **not associated with purposeful behaviors** like talking to classmates, making jokes, or blurting out answers.
ADHD subtypes and diagnostic criteria US Medical PG Question 5: An 11-year-old boy is brought to the physician by his mother because of teacher complaints regarding his poor performance at school for the past 8 months. He has difficulty sustaining attention when assigned school-related tasks, does not follow the teachers' instructions, and makes careless mistakes in his homework. He often blurts out answers in class and has difficulty adhering to the rules during soccer practice. His mother reports that he is easily distracted when she speaks with him and that he often forgets his books at school. Physical examination shows no abnormalities. The patient is started on the appropriate first-line therapy. This boy is at increased risk for which of the following conditions?
- A. Elevated blood pressure (Correct Answer)
- B. Serotonin syndrome
- C. Increased BMI
- D. Prolonged QT interval
- E. Decreased perspiration
ADHD subtypes and diagnostic criteria Explanation: ***Elevated blood pressure***
- This boy's symptoms are highly suggestive of **ADHD** (Attention-Deficit/Hyperactivity Disorder), which is commonly treated with **stimulant medications** like methylphenidate or amphetamines.
- Stimulants can cause **cardiovascular side effects**, including **elevated blood pressure** and heart rate, warranting regular monitoring.
*Serotonin syndrome*
- **Serotonin syndrome** is a risk associated with medications that increase serotonin levels, such as **SSRIs** or MAO inhibitors, which are not typically first-line for ADHD.
- Characterized by altered mental status, autonomic dysfunction, and neuromuscular abnormalities, symptoms not directly caused by stimulant therapy.
*Increased BMI*
- Medications for ADHD, particularly stimulants, are more commonly associated with **decreased appetite** and **weight loss**, not an increased BMI.
- **Appetite suppression** leading to difficulty gaining weight is a known side effect in children taking these medications.
*Prolonged QT interval*
- While some psychiatric medications can prolong the QT interval (e.g., certain antipsychotics or TCAs), **stimulants** used for ADHD are generally not a primary cause of this.
- **ECG monitoring** may be considered for patients with pre-existing cardiac conditions, but it's not a common direct side effect for healthy individuals on stimulants.
*Decreased perspiration*
- Stimulant medications for ADHD can sometimes lead to **increased sweating** (hyperhidrosis) as a side effect, rather than decreased perspiration.
- **Autonomic nervous system changes** due to stimulants can include enhanced sympathetic activity, which can manifest as increased sweating.
ADHD subtypes and diagnostic criteria US Medical PG Question 6: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
- A. "Does the diarrhea typically precede the constipation, or vice-versa?"
- B. "Is the diarrhea foul-smelling?"
- C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
- D. "Are the symptoms worse in the morning or at night?"
- E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)
ADHD subtypes and diagnostic criteria Explanation: ***Can you tell me more about the symptoms you have been experiencing?***
- This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis.
- In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions.
*Does the diarrhea typically precede the constipation, or vice-versa?*
- While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience.
- It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture.
*Is the diarrhea foul-smelling?*
- Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions.
- However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed.
*Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life*
- Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time.
- However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially.
*Are the symptoms worse in the morning or at night?*
- Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related.
- This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.
ADHD subtypes and diagnostic criteria US Medical PG Question 7: A 9-year-old boy is brought to a pediatric psychologist by his mother because of poor academic performance. The patient’s mother mentions that his academic performance was excellent in kindergarten and first grade, but his second and third-grade teachers complain that he is extremely talkative, does not complete schoolwork, and frequently makes careless mistakes. They also complain that he frequently looks at other students or outside the window during the class and is often lost during the lessons. At home, he is very talkative and disorganized. When the pediatrician asks the boy his name, he replies promptly. He was born at full term by spontaneous vaginal delivery. He is up-to-date on all vaccinations and has met all developmental milestones on time. A recent IQ test scored him at 95. His physical examination is completely normal. When he is asked to read from an age-appropriate children’s book, he reads it fluently and correctly. Which of the following is the most likely diagnosis in this patient?
- A. Intellectual disability
- B. Autism spectrum disorder
- C. Dyslexia
- D. Persistent depressive disorder
- E. Attention-deficit/hyperactivity disorder (Correct Answer)
ADHD subtypes and diagnostic criteria Explanation: **Attention-deficit/hyperactivity disorder**
* The child's symptoms of being **extremely talkative**, not completing schoolwork, making **careless mistakes**, and being easily distracted and disorganized are classic signs of **ADHD (Attention-deficit/hyperactivity disorder)**.
* His normal IQ, early developmental milestones, and reading fluency rule out other neurological or intellectual disabilities, while his persistent inattention and hyperactivity across settings support ADHD.
* *Intellectual disability*
* **Intellectual disability** is characterized by significant limitations in both intellectual functioning (IQ below 70) and adaptive behavior, which is contradicted by this patient's **IQ of 95** and normal developmental milestones.
* Patients with intellectual disability would typically struggle with academic performance from the start and would not have had "excellent" performance in kindergarten and first grade.
* *Autism spectrum disorder*
* **Autism spectrum disorder** involves persistent deficits in **social communication and interaction** and **restricted, repetitive patterns of behavior, interests, or activities**. This child's prompt response to his name and ability to read fluently do not align with common autistic features.
* While some social difficulties might arise from inattention, the primary symptoms do not point to core deficits in social reciprocity or communication typical of ASD.
* *Dyslexia*
* **Dyslexia** is a **specific learning disorder** primarily characterized by difficulties with **accurate and/or fluent word recognition, poor decoding, and poor spelling abilities**, despite normal intelligence.
* This patient can **read fluently and correctly from an age-appropriate children’s book**, making dyslexia an unlikely diagnosis.
* *Persistent depressive disorder*
* **Persistent depressive disorder** (dysthymia) involves a **chronically depressed mood** for at least one year in children and adolescents, often accompanied by symptoms such as low energy, poor concentration, sleep disturbance, and feelings of hopelessness.
* While poor academic performance and some difficulty concentrating could be present, the prominent symptoms of **hyperactivity** (talkativeness) and impulsivity (careless mistakes) are not typical features of depression, and a depressed mood is not reported.
ADHD subtypes and diagnostic criteria US Medical PG Question 8: An 11-year-old boy’s parents brought him to a psychologist upon referral from the boy’s school teacher. The boy frequently bullies his younger classmates despite having been punished several times for this. His mother also reported that a year prior, she received complaints that the boy shoplifted from local shops in his neighborhood. The boy frequently stays out at night despite strict instructions by his parents to return home by 10 PM. Detailed history reveals that apart from such behavior, he is usually not angry or irritable. Although his abnormal behavior continues despite warnings and punishments, he neither argues with his parents nor teachers and does not display verbal or physical aggression. Which of the following is the most likely diagnosis?
- A. Attention-deficit/hyperactivity disorder, hyperactivity-impulsivity type
- B. Disruptive mood dysregulation disorder
- C. Intermittent explosive disorder
- D. Conduct disorder (Correct Answer)
- E. Oppositional defiant disorder
ADHD subtypes and diagnostic criteria Explanation: ***Conduct disorder***
- The boy's behaviors, including **bullying**, **shoplifting**, and **violating rules** (staying out past curfew), represent a persistent pattern of behavior that violates the basic rights of others or major age-appropriate societal norms, which are core features of **conduct disorder**.
- The history indicates these behaviors have been ongoing for at least a year and are not just isolated incidents, fulfilling the diagnostic criteria for **duration and pervasiveness**.
*Attention-deficit/hyperactivity disorder, hyperactivity-impulsivity type*
- While ADHD involves **hyperactivity** and **impulsivity**, it does not typically manifest with deliberate violations of others' rights or societal norms like **bullying** and **shoplifting**.
- There is no mention of symptoms such as **difficulty sustaining attention**, **fidgeting**, or **excessive talking** which are characteristic of ADHD.
*Disruptive mood dysregulation disorder*
- This disorder is characterized by **severe recurrent temper outbursts** and persistent **irritable or angry mood** between outbursts.
- The case explicitly states the boy is "not angry or irritable" and "neither argues with his parents nor teachers," ruling out this diagnosis.
*Intermittent explosive disorder*
- This disorder involves recurrent behavioral outbursts representing a failure to control aggressive impulses, often with verbal aggression or physical aggression toward property, animals, or other individuals.
- The boy does not display verbal or physical aggression and is not noted to have anger or irritability, which are central to this diagnosis.
*Oppositional defiant disorder*
- ODD involves a pattern of **angry/irritable mood**, **argumentative/defiant behavior**, or **vindictiveness**.
- While violating rules is present, **bullying** and **shoplifting** (which violate the basic rights of others) are more severe behaviors that go beyond the scope of ODD and are characteristic of conduct disorder.
ADHD subtypes and diagnostic criteria US Medical PG Question 9: A 28-year-old woman is brought to the emergency department by her friends. She is naked except for a blanket and speaking rapidly and incoherently. Her friends say that she was found watering her garden naked and refused to put on any clothes when they tried to make her do so, saying that she has accepted how beautiful she is inside and out. Her friends say she has also purchased a new car she can not afford. They are concerned about her, as they have never seen her behave this way before. For the past week, she has not shown up at work and has been acting ‘strangely’. They say she was extremely excited and has been calling them at odd hours of the night to tell them about her future plans. Which of the following drug mechanisms will help with the long-term management this patient’s symptoms?
- A. Inhibition of inositol monophosphatase and inositol polyphosphate 1-phosphatase (Correct Answer)
- B. Increase the concentration of dopamine and norepinephrine at the synaptic cleft
- C. Modulate the activity of gamma-aminobutyric acid receptors
- D. Acts as an antagonist at the dopamine, serotonin and adrenergic receptors
- E. Inhibit the reuptake of norepinephrine and serotonin from the presynaptic cleft
ADHD subtypes and diagnostic criteria Explanation: ***Inhibition of inositol monophosphatase and inositol polyphosphate 1-phosphatase***
- The patient's symptoms (euphoria, grandiosity, reduced need for sleep, impulsivity, rapid speech, and unusual behavior) are classic for a **manic episode**, strongly suggesting **bipolar disorder**.
- **Lithium** is a mood stabilizer used for long-term management of bipolar disorder, and its primary molecular action is thought to involve the **inhibition of inositol phosphatases**, thereby depleting inositol and modulating intracellular signaling.
*Increase the concentration of dopamine and norepinephrine at the synaptic cleft*
- This mechanism describes the action of **stimulants** or some **antidepressants** (like TCAs or SNRIs), which could exacerbate manic symptoms in bipolar disorder.
- Increasing dopamine and norepinephrine would likely worsen the current patient's **hyperactivity**, **agitation**, and **psychosis**.
*Inhibit the reuptake norepinephrine and serotonin from the presynaptic cleft*
- This mechanism is characteristic of **antidepressants** (e.g., SSRIs, SNRIs) used to treat depression.
- Administering such drugs during a manic episode can precipitate or worsen **mania** or induce **rapid cycling** in bipolar patients.
*Modulate the activity of Ƴ-aminobutyric acid receptors*
- This describes the action of **benzodiazepines** or some **antiepileptic drugs** (e.g., valproate, lamotrigine).
- While some antiepileptic drugs (like valproate) are used as mood stabilizers, the direct modulation of GABA receptors to **increase GABAergic activity** (as with benzodiazepines) is typically for acute agitation and anxiety, not the primary long-term mood stabilization for bipolar disorder.
*Acts as an antagonist at the dopamine, serotonin, and adrenergic receptors*
- This mechanism generally describes the action of **antipsychotic medications** (e.g., olanzapine, quetiapine, risperidone).
- While antipsychotics are effective for acute mania and some are used in long-term maintenance of bipolar disorder, the question asks for the primary drug mechanism for long-term management which is **Lithium's mechanism of action**, targeting intracellular signaling rather than broad receptor antagonism.
ADHD subtypes and diagnostic criteria US Medical PG Question 10: A 21-year-old man presents to the clinic complaining of feeling tired during the day. He is concerned as his grades in school have worsened and he does not want to lose his scholarship. Upon further questioning, the patient describes frequently experiencing a dreamlike state before falling asleep and after waking up. He also has frequent nighttime awakenings where he finds himself unable to move. He denies snoring. The patient does not drink alcohol or abuse any other drugs. The patient's BMI is 21 kg/m2, and his vital signs are all within normal limits. What is this patient's diagnosis?
- A. Obstructive sleep apnea (OSA)
- B. Insomnia
- C. Alcohol withdrawal
- D. Delayed sleep phase syndrome (DSPS)
- E. Narcolepsy (Correct Answer)
ADHD subtypes and diagnostic criteria Explanation: ***Narcolepsy***
- The patient's symptoms of **excessive daytime sleepiness**, **hypnagogic/hypnopompic hallucinations** (dreamlike state before falling asleep and after waking up), and **sleep paralysis** (unable to move during nighttime awakenings) are the **classic tetrad of narcolepsy** (cataplexy is the 4th feature, not present here).
- The absence of snoring, normal BMI, and lack of alcohol/drug use rule out other common causes of sleep disturbances, supporting the diagnosis of narcolepsy.
- Narcolepsy is a **chronic sleep-wake disorder** caused by hypothalamic hypocretin (orexin) deficiency.
*Obstructive sleep apnea (OSA)*
- While OSA also causes **daytime sleepiness**, a key feature is **snoring**, which this patient denies.
- OSA is often associated with obesity, but this patient has a **normal BMI of 21 kg/m²**.
- OSA would not explain the hypnagogic hallucinations or sleep paralysis.
*Insomnia*
- Insomnia primarily involves difficulty initiating or maintaining sleep, leading to **insufficient sleep quantity or quality**.
- This patient's symptoms are more specific, including episodes of sleep paralysis and vivid dreamlike states, rather than just general difficulty sleeping.
- The hallmark features of narcolepsy distinguish this from simple insomnia.
*Alcohol withdrawal*
- Alcohol withdrawal can cause **sleep disturbances**, but it is typically accompanied by other symptoms like tremors, anxiety, autonomic hyperactivity, and potentially seizures, none of which are present.
- The patient **explicitly denies drinking alcohol**, making this diagnosis highly unlikely.
*Delayed sleep phase syndrome (DSPS)*
- DSPS is a **circadian rhythm disorder** characterized by a delayed sleep-wake cycle, where individuals fall asleep and wake up later than desired.
- While it can cause daytime fatigue if individuals are forced to wake up early, it does **not** involve the specific symptoms of hypnagogic/hypnopompic hallucinations or sleep paralysis seen in this patient.
- DSPS is primarily a timing issue, not a neurological sleep disorder.
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