Neurobiology of ADHD US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Neurobiology of ADHD. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Neurobiology of ADHD 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
Neurobiology of ADHD 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.
Neurobiology of ADHD US Medical PG Question 2: A 7-year-old boy is brought to the physician because of repetitive, involuntary blinking, shrugging, and grunting for the past year. His mother states that his symptoms improve when he is physically active, while tiredness, boredom, and stress aggravate them. He has felt increasingly embarrassed by his symptoms in school, and his grades have been dropping from average levels. He has met all his developmental milestones. Vital signs are within normal limits. Mental status examination shows intact higher mental functioning and thought processes. Excessive blinking, grunting, and jerking of the shoulders and neck occur while at rest. The remainder of the examination shows no abnormalities. This patient's condition is most likely associated with which of the following findings?
- A. Feelings of persistent sadness and loss of interest
- B. Defiant and hostile behavior toward teachers and parents
- C. Recurrent episodes of intense fear
- D. Chorea and hyperreflexia
- E. Excessive impulsivity and inattention (Correct Answer)
Neurobiology of ADHD Explanation: ***Excessive impulsivity and inattention***
- The patient exhibits features of **Tourette syndrome**, characterized by multiple motor **tics** and at least one vocal tic present for longer than a year, with onset before age 18.
- Tourette syndrome is frequently comorbid with **attention-deficit/hyperactivity disorder (ADHD)**, which presents with symptoms of **inattention** and **hyperactivity-impulsivity**.
*Feelings of persistent sadness and loss of interest*
- These symptoms describe **major depressive disorder**, which is less commonly comorbid with Tourette syndrome in childhood and less directly linked than ADHD.
- While depression can occur, the primary associations with Tourette's during childhood are more behavioral and attention-related.
*Defiant and hostile behavior toward teachers and parents*
- This symptom profile suggests **oppositional defiant disorder (ODD)** or **conduct disorder**, which are less common comorbidities of Tourette syndrome than ADHD.
- While behavioral issues can arise from the distress of tics, ODD is not the most direct or prevalent comorbidity.
*Recurrent episodes of intense fear*
- This symptom describes **panic attacks** or an **anxiety disorder**, which can co-occur with Tourette syndrome, but less frequently than ADHD.
- The primary clinical picture presented (tics and academic decline) points more strongly to an attention-related comorbidity.
*Chorea and hyperreflexia*
- **Chorea** and **hyperreflexia** are neurological signs not typically associated with Tourette syndrome; they are more characteristic of conditions like Huntington's disease or Sydenham chorea.
- Tourette syndrome is a **neurological disorder** of tics, not a progressive degenerative disorder with chorea and hyperreflexia.
Neurobiology of ADHD US Medical PG Question 3: A 14-year-old boy is brought in to the clinic by his parents for weird behavior for the past 4 months. The father reports that since the passing of his son's pet rabbit about 5 months ago, his son has been counting during meals. It could take up to 2 hours for him to finish a meal as he would cut up all his food and arrange it in a certain way. After asking the parents to leave the room, you inquire about the reason for these behaviors. He believes that another family member is going to die a “terrible death” if he doesn’t eat his meals in multiples of 5. He understands that this is unreasonable but just can’t bring himself to stop. Which of the following abnormality is this patient's condition most likely associated with?
- A. Atrophy of the hippocampus
- B. Atrophy of the frontotemporal lobes
- C. Enlargement of the ventricles
- D. Decreased level of serotonin (Correct Answer)
- E. Increased activity of the caudate
Neurobiology of ADHD Explanation: ***Decreased level of serotonin***
- Obsessive-compulsive disorder (OCD), characterized by **obsessions (intrusive thoughts)** and **compulsions (repetitive behaviors)**, is strongly linked to dysregulation of the **serotonin system**.
- Medications that **increase serotonin levels**, such as selective serotonin reuptake inhibitors (SSRIs), are the first-line pharmacologic treatment for OCD.
*Atrophy of the hippocampus*
- **Hippocampal atrophy** is more commonly associated with conditions like **Alzheimer's disease** and other dementias, affecting memory and learning.
- It is not a primary neurobiological feature of OCD.
*Atrophy of the frontotemporal lobes*
- **Frontotemporal lobe atrophy** is characteristic of **frontotemporal dementia**, leading to changes in personality, behavior, and language.
- This is distinct from the symptom presentation of OCD.
*Enlargement of the ventricles*
- **Ventricular enlargement** is most commonly seen in conditions like **schizophrenia** and **hydrocephalus**, indicating a loss of brain tissue or increased cerebrospinal fluid pressure.
- It is not a typical finding in OCD.
*Increased activity of the caudate*
- While there are neuroimaging studies suggesting **increased caudate nucleus activity** in OCD, this is a distinct phenomenon from decreased serotonin levels.
- **Increased activity in the orbitofrontal cortex, anterior cingulate cortex, and basal ganglia (including the caudate)** are structural and functional abnormalities often observed, but the primary biochemical imbalance widely targeted in treatment is serotonin.
Neurobiology of ADHD US Medical PG Question 4: A 40-year-old man is brought to the emergency department after sustaining multiple lacerations during a bar fight. The patient’s wife says that he has been showing worsening aggression and has been involved in a lot of arguments and fights for the past 2 years. The patient has no significant past medical or psychiatric history and currently takes no medications. The patient cannot provide any relevant family history since he was adopted as an infant. His vitals are within normal limits. On physical examination, the patient looks apathetic and grimaces repeatedly. Suddenly, his arms start to swing by his side in an uncontrolled manner. Which area of the brain is most likely affected in this patient?
- A. Cerebral cortex
- B. Caudate nucleus (Correct Answer)
- C. Cerebellum
- D. Medulla oblongata
- E. Substantia nigra
Neurobiology of ADHD Explanation: **Caudate nucleus**
- The patient exhibits features like **worsening aggression**, **apathy**, and **uncontrolled, sudden movements** of the limbs, which are characteristic of Huntington's disease, a condition primarily affecting the **caudate nucleus**.
- **Huntington's disease** is an autosomal dominant neurodegenerative disorder linked to a trinucleotide repeat expansion (CAG) on chromosome 4, leading to atrophy of the **caudate and putamen**.
*Cerebral cortex*
- While damage to the cerebral cortex can cause personality changes and motor deficits, the specific combination of **choreiform movements** and progressive cognitive/behavioral decline seen here is more indicative of a basal ganglia disorder like Huntington's.
- Cortical lesions more commonly present with **focal neurological deficits** such as hemiparesis, aphasia, or sensory loss, which are not the primary features described.
*Cerebellum*
- Damage to the cerebellum typically results in **ataxia**, **dysmetria**, **intention tremor**, and problems with balance and coordination.
- The patient's **uncontrolled, sudden limb movements** are characteristic of chorea, not cerebellar dysfunction.
*Medulla oblongata*
- The medulla oblongata is crucial for vital autonomic functions such as **breathing, heart rate, and blood pressure regulation**.
- Lesions in this area would likely cause life-threatening symptoms, including **respiratory failure** or severe cardiovascular instability, which are not present in this patient.
*Substantia nigra*
- Damage or degeneration of the substantia nigra is primarily associated with **Parkinson's disease**, leading to symptoms like **bradykinesia**, **rigidity**, **resting tremor**, and **postural instability**.
- The patient's **hyperkinetic movements** (choreiform movements) are opposite to the hypokinetic presentation of Parkinson's disease.
Neurobiology of ADHD US Medical PG Question 5: A 22-year-old man is brought to the physician by his mother because of concerns about his recent behavior. Three months ago, the patient first reported hearing loud voices coming from the ceiling of his room. During this time, he has also become increasingly worried that visitors to the house were placing secret surveillance cameras. Mental status examination shows tangential speech with paranoid thoughts. Treatment for this patient's condition predominantly targets which of the following dopaminergic pathways?
- A. Mesocortical pathway
- B. Thalamocortical pathway
- C. Nigrostriatal pathway
- D. Corticostriatal pathway
- E. Mesolimbic pathway (Correct Answer)
Neurobiology of ADHD Explanation: ***Mesolimbic pathway***
- The patient's symptoms of **auditory hallucinations** and **paranoid delusions** are **positive symptoms** of psychosis consistent with **schizophrenia**.
- **Hyperactivity** of the **mesolimbic dopaminergic pathway** is strongly associated with the positive symptoms of schizophrenia, making it the primary target for antipsychotic treatment.
*Mesocortical pathway*
- The **mesocortical pathway** is primarily involved in **cognition, motivation, and executive functions**, originating from the ventral tegmental area and projecting to the prefrontal cortex.
- **Hypoactivity** in this pathway is thought to contribute to the **negative and cognitive symptoms** of schizophrenia, not the positive symptoms described.
*Thalamocortical pathway*
- The **thalamocortical pathway** connects the **thalamus to the cerebral cortex** and is crucial for sensory processing, arousal, and consciousness.
- While involved in neural circuits, it is not considered a primary dopaminergic pathway targeted for the treatment of positive psychotic symptoms.
*Nigrostriatal pathway*
- The **nigrostriatal pathway** projects from the **substantia nigra to the striatum** and is primarily involved in **motor control**.
- Blocking dopamine receptors in this pathway by antipsychotic medications can cause **extrapyramidal symptoms (EPS)**, but it is not the main pathway responsible for positive psychotic symptoms or their treatment.
*Corticostriatal pathway*
- The **corticostriatal pathway** is **predominantly a glutamatergic pathway** connecting the **cerebral cortex to the striatum**, playing a role in motor control and habit formation.
- This is not a primary dopaminergic pathway and is not directly implicated in the positive symptoms of schizophrenia or their pharmacological treatment.
Neurobiology of ADHD US Medical PG Question 6: A 7-year-old boy is brought in to clinic by his parents with a chief concern of poor performance in school. The parents were told by the teacher that the student often does not turn in assignments, and when he does they are partially complete. The child also often shouts out answers to questions and has trouble participating in class sports as he does not follow the rules. The parents of this child also note similar behaviors at home and have trouble getting their child to focus on any task such as reading. The child is even unable to watch full episodes of his favorite television show without getting distracted by other activities. The child begins a trial of behavioral therapy that fails. The physician then tries pharmacological therapy. Which of the following is most likely the mechanism of action of an appropriate treatment for this child's condition?
- A. Increases the frequency of GABAa channel opening
- B. Increases the duration of GABAa channel opening
- C. Decreases synaptic reuptake of norepinephrine and dopamine (Correct Answer)
- D. Blockade of D2 receptors
- E. Antagonizes NMDA receptors
Neurobiology of ADHD Explanation: ***Decreases synaptic reuptake of norepinephrine and dopamine***
- The presented symptoms (inattention, impulsivity, hyperactivity) are characteristic of **Attention-Deficit/Hyperactivity Disorder (ADHD)**.
- The most common pharmacological treatments for ADHD are **stimulants** (e.g., methylphenidate, amphetamines) which work by **inhibiting the reuptake of norepinephrine and dopamine**, thereby increasing their synaptic concentrations.
*Increases the frequency of GABAa channel opening*
- This is the mechanism of action for **benzodiazepines**, which are primarily used for anxiety, seizures, and insomnia.
- Benzodiazepines are not indicated for ADHD and would likely worsen symptoms due to their sedative effects.
*Increases the duration of GABAa channel opening*
- This describes the mechanism of action of **barbiturates**, which are potent central nervous system depressants.
- Like benzodiazepines, barbiturates are not used for ADHD and would have inappropriate sedative side effects.
*Blockade of D2 receptors*
- This is the primary mechanism of action for **antipsychotic medications**, used to treat conditions like schizophrenia or bipolar disorder.
- Blocking D2 receptors would likely cause side effects such as drowsiness and extrapyramidal symptoms, and would not address the core symptoms of ADHD.
*Antagonizes NMDA receptors*
- NMDA receptor antagonists (e.g., memantine, ketamine) are used in conditions like **Alzheimer's disease** or for anesthetic purposes.
- This mechanism is not relevant to the treatment of ADHD; enhancing NMDA receptor activity might actually be beneficial in some cognitive disorders.
Neurobiology of ADHD US Medical PG Question 7: An 11-year-old boy is brought to the clinic by his parents for poor academic performance. The patient’s parents say that his teacher told them that he may have to repeat a grade because of his lack of progress, as he does not pay attention to the lessons, tends to fidget about in his seat, and often blurts out comments when it is someone else’s turn to speak. Furthermore, his after-school karate coach says the patient no longer listens to instructions and has a hard time focusing on the activity at hand. The patient has no significant past medical history and is currently not on any medications. The patient has no known learning disabilities and has been meeting all developmental milestones. The parents are vehemently opposed to using any medication with a potential for addiction. Which of the following medications is the best course of treatment for this patient?
- A. Sertraline
- B. Diazepam
- C. Olanzapine
- D. Methylphenidate
- E. Atomoxetine (Correct Answer)
Neurobiology of ADHD Explanation: ***Atomoxetine***
- This medication is a **non-stimulant** selective norepinephrine reuptake inhibitor. It is a good choice for **ADHD patients** whose parents are opposed to any medication with a potential for addiction because it does not have the same addictive potential as stimulants.
- It works by increasing the levels of **norepinephrine** in the brain, improving attention and hyperactivity symptoms typically seen in ADHD.
*Sertraline*
- This is a **selective serotonin reuptake inhibitor (SSRI)** and is primarily used to treat depression, anxiety disorders, and obsessive-compulsive disorder.
- Sertraline would not be effective for ADHD symptoms like inattention and hyperactivity.
*Diazepam*
- This is a **benzodiazepine** primarily used for anxiety, seizures, and muscle spasms due to its sedative and anxiolytic properties.
- It would likely worsen the patient's inattention and academic performance due to its **sedative effects** and has a significant potential for addiction.
*Olanzapine*
- This is an **atypical antipsychotic** medication used to treat conditions like schizophrenia and bipolar disorder.
- Olanzapine is not indicated for ADHD and could cause severe side effects like **sedation, weight gain, and metabolic issues**.
*Methylphenidate*
- This is a **stimulant medication** commonly used to treat ADHD and is highly effective in improving attention and reducing hyperactivity.
- While effective, methylphenidate has a **potential for abuse and addiction**, which the patient's parents are explicitly against.
Neurobiology of ADHD US Medical PG Question 8: 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)
Neurobiology of ADHD 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.
Neurobiology of ADHD US Medical PG Question 9: A 19-year-old man presents to the emergency room after a suicidal gesture following a fight with his new girlfriend. He tearfully tells you that she is “definitely the one," unlike his numerous previous girlfriends, who were "all mean and selfish” and with whom he frequently fought. During this fight, his current girlfriend suggested that they spend time apart, so he opened a window and threatened to jump unless she promised to never leave him. You gather that his other relationships have ended in similar ways. He endorses impulsive behaviors and describes his moods as “intense” and rapidly changing in response to people around him. He often feels “depressed” for one day and then elated the next. You notice several superficial cuts and scars on the patient’s arms and wrists, and he admits to cutting his wrists in order to “feel something other than my emptiness.” Which of the following is the most likely diagnosis for this patient?
- A. Bipolar I disorder
- B. Major depressive disorder
- C. Borderline personality disorder (Correct Answer)
- D. Bipolar II disorder
- E. Histrionic personality disorder
Neurobiology of ADHD Explanation: ***Borderline personality disorder***
- This patient exhibits characteristic features of **borderline personality disorder (BPD)**, including a pattern of **unstable relationships** marked by idealization ("definitely the one") and devaluation ("all mean and selfish").
- Other key features are **impulsivity** (suicidal gesture, cutting), **affective instability** ("intense" and rapidly changing moods), chronic feelings of **emptiness**, and a history of **self-harm** (superficial cuts and scars).
*Bipolar I disorder*
- While the patient describes rapidly changing and "intense" moods, the rapid shifts over days and reactivity to others are more characteristic of **mood lability** in BPD than distinct **manic or hypomanic episodes** lasting several days or longer, which define bipolar disorder.
- The suicidal gesture stemming from interpersonal conflict and fear of abandonment, combined with chronic self-harm, points strongly away from a primary mood disorder.
*Major depressive disorder*
- Although the patient reports feeling "depressed," the predominant features are not a persistent depressed mood or anhedonia but rather **unstable relationships**, **impulsivity**, and **affective dysregulation** beyond typical depressive symptoms.
- The "elated" periods described are also inconsistent with unipolar depression.
*Bipolar II disorder*
- This diagnosis requires a history of at least one **major depressive episode** and at least one **hypomanic episode**. While the patient describes mood shifts, they are described as "rapidly changing in response to people around him" and lasting for a day, which is more consistent with **affective instability** seen in BPD rather than sustained hypomanic episodes.
- The prominent features of self-harm and unstable relationships are not central to Bipolar II disorder.
*Histrionic personality disorder*
- Patients with **histrionic personality disorder** typically display excessive emotionality and attention-seeking behavior, often with a theatrical presentation.
- While there may be some overlap in attention-seeking aspects (suicidal gesture), the profound **instability of mood**, chronic **emptiness**, self-harm, and intense **fear of abandonment** are core to BPD and less characteristic of histrionic traits.
Neurobiology of ADHD US Medical PG Question 10: A 4-year-old boy presents with language delay, toe-walking, hand-flapping, and intense interest in trains. He makes poor eye contact but occasionally engages in joint attention with his mother when looking at trains. He has sensory sensitivities to loud noises. He can identify all letters and numbers but cannot have reciprocal conversations. His Childhood Autism Rating Scale (CARS) score is borderline. His parents request your opinion on diagnosis and intervention priorities given diagnostic uncertainty and limited early intervention resources in their area.
- A. Presume autism spectrum disorder and implement evidence-based early interventions while monitoring (Correct Answer)
- B. Diagnose autism spectrum disorder and begin comprehensive ABA therapy immediately
- C. Diagnose language disorder and focus resources on communication training
- D. Refer to genetics for testing before committing to diagnosis or intervention
- E. Delay diagnosis pending further developmental assessment and prioritize speech therapy
Neurobiology of ADHD Explanation: ***Presume autism spectrum disorder and implement evidence-based early interventions while monitoring***
- The clinical presentation of **stereotyped behaviors** (hand-flapping, toe-walking), **restricted interests** (trains), and **social communication deficits** warrants early intervention during the critical **neuroplastic window** (ages 2-5).
- Given the diagnostic uncertainty and limited resources, a **provisional diagnosis** ensures the child receives broad-based support for functional deficits while longitudinal monitoring clarifies the diagnosis.
*Diagnose autism spectrum disorder and begin comprehensive ABA therapy immediately*
- While ASD is highly likely, a definitive diagnosis may be premature given the **borderline CARS score** and elements of **joint attention** that require further assessment.
- Immediate **comprehensive ABA therapy** might be resource-intensive and may not be the only or most appropriate option in an area with limited early intervention resources.
*Diagnose language disorder and focus resources on communication training*
- A **language disorder** diagnosis ignores the significant **repetitive behaviors**, **sensory sensitivities**, and **restricted interests** characteristic of ASD.
- Focusing solely on communication training fails to address the child's **social-emotional** and **behavioral needs**, which are central to his presentation.
*Refer to genetics for testing before committing to diagnosis or intervention*
- While **genetic testing** (e.g., chromosomal microarray) is recommended for ASD workups, it should not cause a **delay in starting intervention**.
- Genetic results rarely change the immediate **behavioral or developmental management** plan required for the child's daily functioning.
*Delay diagnosis pending further developmental assessment and prioritize speech therapy*
- Delaying diagnosis and intervention until further assessment can lead to the loss of valuable time during a peak period of **brain development**.
- Prioritizing **speech therapy** alone is insufficient because it does not address the **social reciprocity** and **sensory processing issues** evident in this patient.
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