Neurobiology of Addiction — MCQs
A 55-year-old drug addict from California presents with euphoria, altered time perception, and conjunctival injection, along with impairment of judgment. The most likely cause of this is addiction to which substance?
A person presents to the outpatient department with tremors and visual hallucinations after a 2-day history of alcohol cessation. What is the diagnosis?
Tolerance to substances is seen in which of the following?
Match the following: A) Glossopharyngeal nerve B) Spinal accessory nerve C) Facial nerve D) Mandibular nerve 1) Shrugging of shoulder 2) Touch sensation from the posterior one-third of the tongue 3) Chewing 4) Taste from the anterior two-thirds of the tongue
Stimulation of which of the following areas of brain is experimentally used to control intractable pain -
Delusion of persecution and formication occur together in
Which of the following is the primary neurotransmitter involved in the transmission of pain signals in the spinal cord?
Which is NOT a common symptom of opioid withdrawal?
Which of the following develop first during dependence of a substance ?
In chronic alcoholism and its complications, which of the following is seen?
Neurobiology of Addiction Indian Medical PG Practice Questions and MCQs
Question 1: A 55-year-old drug addict from California presents with euphoria, altered time perception, and conjunctival injection, along with impairment of judgment. The most likely cause of this is addiction to which substance?
- A. Marijuana (Correct Answer)
- B. Cocaine
- C. Phencyclidine
- D. Benzodiazepine
Explanation: ***Marijuana*** - **Euphoria**, altered time perception, and **conjunctival injection** are classic symptoms associated with marijuana use. - Impairment of judgment and coordination are also common effects of **cannabis intoxication**. *Cocaine* - Cocaine intoxication typically presents with **psychomotor agitation**, **tachycardia**, **hypertension**, and **dilated pupils**, not conjunctival injection. - While it causes euphoria and altered perception, the specific combination of symptoms points away from cocaine. *Phencyclidine* - **Phencyclidine (PCP)** often causes **nystagmus**, violence, and **dissociative symptoms** like derealization and depersonalization, which are not described. - It can also lead to severe agitation and unpredictable behavior, distinct from the patient's presentation. *Benzodiazepine* - Benzodiazepine intoxication or abuse typically leads to **sedation**, ataxia, and **respiratory depression**, rather than euphoria and conjunctival injection. - The effects are more consistent with central nervous system depression.
Question 2: A person presents to the outpatient department with tremors and visual hallucinations after a 2-day history of alcohol cessation. What is the diagnosis?
- A. Korsakoff’s psychosis
- B. Delirium tremens (Correct Answer)
- C. Wernicke encephalopathy
- D. Alcoholic hallucinosis
Explanation: ***Delirium tremens*** - Delirium tremens is a severe form of **alcohol withdrawal** characterized by **tremors**, disorientation, and **visual hallucinations**, typically appearing **48 to 96 hours** (2-4 days) after the last drink. - This is a medical emergency with potential for **seizures**, **hyperthermia**, and **cardiovascular collapse** due to dysregulation of neurotransmitters (decreased **GABA** activity and increased **glutamate** activity). - Autonomic hyperactivity (tachycardia, hypertension, diaphoresis) is a key feature distinguishing it from other alcohol-related conditions. *Korsakoff's psychosis* - This is a chronic **neuropsychiatric syndrome** typically occurring after an episode of **Wernicke encephalopathy**, characterized by severe **memory impairment** (anterograde and retrograde amnesia) and **confabulation**. - It develops over weeks to months in the course of chronic alcoholism and is **not an acute withdrawal syndrome**, unlike the symptoms described in this 2-day presentation. *Wernicke encephalopathy* - This is an acute neurological condition caused by **thiamine (vitamin B1) deficiency**, commonly seen in chronic alcoholics, characterized by the classic triad of **ophthalmoplegia** (especially nystagmus), **ataxia**, and **confusion**. - While it can precede Korsakoff's psychosis and involves confusion, it does not typically present with the prominent **tremors** and **visual hallucinations** characteristic of alcohol withdrawal, and the timing (2 days post-cessation) points more toward withdrawal rather than nutritional deficiency. *Alcoholic hallucinosis* - Alcoholic hallucinosis involves primarily **auditory hallucinations** (often threatening voices) that occur without significant clouding of consciousness, typically within **12-24 hours** of alcohol cessation. - Unlike delirium tremens, it **lacks autonomic instability**, severe tremors, and global disorientation, and the hallucinations are predominantly auditory rather than visual.
Question 3: Tolerance to substances is seen in which of the following?
- A. Obsessive-compulsive disorder
- B. Physiological dependence (Correct Answer)
- C. Hypochondriasis
- D. Psychological dependence
Explanation: ***Physiological dependence*** - **Tolerance** is a hallmark feature of physiological dependence, where the body adapts to a substance, requiring increasingly larger doses to achieve the initial effect. - It involves neurobiological adaptations in the brain in response to chronic substance use. - Physiological dependence is characterized by both **tolerance** and **withdrawal symptoms** as key features. *Hypochondriasis* - This is a mental disorder characterized by an excessive preoccupation with having a serious illness, despite medical reassurance. - It does not involve substance use or development of tolerance to a substance. *Obsessive-compulsive disorder* - OCD is an anxiety disorder marked by recurrent unwanted thoughts (**obsessions**) and repetitive behaviors (**compulsions**). - It is not related to substance use, tolerance, or dependence. *Psychological dependence* - Psychological dependence involves a strong emotional or mental desire for a drug, characterized by craving and compulsive drug-seeking behavior. - While psychological dependence can coexist with tolerance, the primary feature is the **emotional craving** rather than the physical adaptation. - **Physiological dependence** more directly encompasses tolerance as a defining characteristic, along with physical withdrawal symptoms.
Question 4: Match the following: A) Glossopharyngeal nerve B) Spinal accessory nerve C) Facial nerve D) Mandibular nerve 1) Shrugging of shoulder 2) Touch sensation from the posterior one-third of the tongue 3) Chewing 4) Taste from the anterior two-thirds of the tongue
- A. A-3 , B-1 , C-4 , D-2
- B. A-2 , B-3 , C-4 , D-1
- C. A-4 , B-1 , C-2 , D-3
- D. A-2 , B-1 , C-4 , D-3 (Correct Answer)
Explanation: ***A-2 , B-1 , C-4 , D-3*** - **A) Glossopharyngeal nerve (CN IX)** is responsible for **general sensation and taste from the posterior one-third of the tongue** [1]. (2). - **B) Spinal Accessory nerve (CN XI)** innervates the **sternocleidomastoid** and **trapezius muscles**, which are involved in shrugging the shoulders (1). - **C) Facial nerve (CN VII)** carries **taste sensation from the anterior two-thirds of the tongue** [1] (4) via the chorda tympani. - **D) Mandibular nerve (V3)**, a branch of the trigeminal nerve, innervates the muscles of mastication, enabling **chewing** (3). *A-3 , B-1 , C-4 , D-2* - This option incorrectly associates the **glossopharyngeal nerve** with chewing, which is a function of the mandibular nerve (V3). - It also incorrectly associates the **mandibular nerve** with touch sensation from the posterior one-third of the tongue, which is a function of the glossopharyngeal nerve [1]. *A-2 , B-3 , C-4 , D-1* - This option incorrectly links the **spinal accessory nerve** with chewing; this nerve primarily controls shoulder and neck movements. - It also incorrectly assigns shrugging of the shoulder to the **mandibular nerve** instead of the spinal accessory nerve. *A-4 , B-1 , C-2 , D-3* - This choice incorrectly attributes **taste from the anterior two-thirds of the tongue** to the glossopharyngeal nerve, which supplies the posterior one-third [1]. - It also incorrectly links **touch sensation from the posterior one-third of the tongue** to the facial nerve, which is involved in taste from the anterior two-thirds [1].
Question 5: Stimulation of which of the following areas of brain is experimentally used to control intractable pain -
- A. Mesencephalon
- B. Subthalamic nucleus
- C. Periaqueductal grey matter (Correct Answer)
- D. Medial forebrain bundle
Explanation: ***Periaqueductal grey matter*** - The **periaqueductal grey (PAG)** is a key modulator of endogenous analgesia, and its stimulation activates descending pain inhibitory pathways. - Stimulation of the PAG leads to the release of **endogenous opioids** (e.g., endorphins, enkephalins) and other neurotransmitters that suppress pain transmission at the spinal cord level. *Mesencephalon* - While the PAG is located within the mesencephalon (midbrain), simply stimulating the broader mesencephalon is not as precise or effective for pain control. - The mesencephalon contains various structures with diverse functions, and non-specific stimulation could lead to unwanted side effects. *Subthalamic nucleus* - The **subthalamic nucleus (STN)** is primarily involved in motor control and is a common target for deep brain stimulation in Parkinson's disease. - Its direct stimulation is not a primary or established method for controlling intractable pain. *Medial forebrain bundle* - The **medial forebrain bundle (MFB)** is a complex pathway associated with reward, motivation, and pleasure, important in the limbic system. - While it plays a role in emotional aspects of pain, its direct stimulation is not a recognized technique for somatic pain management.
Question 6: Delusion of persecution and formication occur together in
- A. LSD
- B. Cocaine (Correct Answer)
- C. Amphetamine
- D. Cannabis
Explanation: ***Cocaine*** - **Chronic cocaine abuse** can lead to **paranoid delusions** (delusions of persecution) and tactile hallucinations such as **formication** (sensation of insects crawling under the skin, called "**cocaine bugs**"). - These symptoms occur together in **cocaine-induced psychosis**, which can mimic **paranoid schizophrenia**. - The combination of **paranoid delusions with formication** is a classical presentation of **stimulant psychosis**, seen with cocaine. *Amphetamine* - **Amphetamine/methamphetamine abuse** can also cause **psychotic symptoms** including paranoia, delusions of persecution, and formication ("**meth mites**"). - While both cocaine and amphetamine can cause this combination, **cocaine** is the **traditional answer** in medical examinations for this specific combination of symptoms. - Clinically, amphetamine-induced formication is increasingly recognized. *LSD* - **Lysergic acid diethylamide (LSD)** primarily causes **visual hallucinations**, altered perceptions, and synesthesia. - While LSD can induce paranoia and anxiety, **delusions of persecution** and **formication** are not typical features. - LSD effects are more perceptual distortions than true psychotic symptoms. *Cannabis* - **Cannabis use** can sometimes induce **acute psychotic episodes** in vulnerable individuals, particularly with high-potency preparations. - Cannabis effects include **anxiety**, **paranoia**, and **depersonalization**. - **Formication** and prominent **delusions of persecution** are not characteristic of cannabis intoxication.
Question 7: Which of the following is the primary neurotransmitter involved in the transmission of pain signals in the spinal cord?
- A. Substance P (Correct Answer)
- B. Dopamine
- C. Serotonin
- D. Gamma-aminobutyric acid (GABA)
Explanation: ***Substance P*** - **Substance P** is a neuropeptide that plays a crucial role in the transmission of **nociceptive (pain) signals** from the periphery to the central nervous system, particularly in the **spinal cord**. - It is released by primary afferent neurons during painful stimuli and contributes to the sensation of pain and **neurogenic inflammation**. *Dopamine* - **Dopamine** is primarily involved in **reward**, motivation, motor control, and pleasure. - While dopamine can influence pain perception, it is not considered the primary neurotransmitter directly responsible for the **transmission of pain signals** in the spinal cord. *Serotonin* - **Serotonin (5-HT)** is involved in mood, sleep, appetite, and a wide range of other functions, including modulation of pain. - Although it can have both **pro-nociceptive and anti-nociceptive effects** depending on its receptor subtype and location, it is not the primary neurotransmitter for pain signal transmission. *Gamma-aminobutyric acid (GABA)* - **GABA** is the main **inhibitory neurotransmitter** in the central nervous system, reducing neuronal excitability. - Its role in pain is primarily to **modulate and inhibit pain signals**, rather than to transmit them.
Question 8: Which is NOT a common symptom of opioid withdrawal?
- A. Seizures (Correct Answer)
- B. Yawning
- C. Insomnia
- D. Diarrhea
Explanation: ***Seizures*** - Seizures are **not typical** of opioid withdrawal; they are more characteristic of withdrawal from substances like **alcohol** or **benzodiazepines**. - Opioid withdrawal symptoms are primarily **autonomic** and **flu-like**, not neurological in the sense of causing seizures. *Yawning* - **Frequent yawning** is a common and early **autonomic symptom** of opioid withdrawal, indicating central nervous system overactivity. - It is often accompanied by other signs of hyperarousal and discomfort. *Insomnia* - **Insomnia** (difficulty sleeping) is a very common and distressing symptom during opioid withdrawal due to heightened central nervous system activity and generalized discomfort. - Patients often experience **restlessness** and an inability to achieve restful sleep. *Diarrhea* - **Diarrhea** is a prominent gastrointestinal symptom of opioid withdrawal, resulting from the cessation of opioid-induced slowing of gut motility. - This symptom reflects the **autonomic hyperactivity** caused by opioid cessation.
Question 9: Which of the following develop first during dependence of a substance ?
- A. Tolerance
- B. Physical dependence
- C. Psychological dependence (Correct Answer)
- D. Withdrawal symptoms
Explanation: ***Psychological dependence*** - **Psychological dependence** often develops first, characterized by an emotional need for the substance to experience pleasure or avoid discomfort. - This involves a strong **craving** and compulsive drug-seeking behavior despite negative consequences, driven by the substance's effect on brain reward pathways. *Tolerance* - **Tolerance** means that increasing doses of the substance are required to achieve the same effect previously achieved with lower doses. - While it often develops early in substance use, the initial "need" to use the substance is often psychological before physiological adaptations occur. *Physical dependence* - **Physical dependence** describes the body's physiological adaptation to the substance, leading to withdrawal symptoms if use is stopped or reduced. - It typically develops after consistent, prolonged use and is usually preceded by psychological dependence and often tolerance. *Withdrawal symptoms* - **Withdrawal symptoms** are the physiological and psychological signs that occur when a dependent person stops or drastically reduces their substance intake. - These are a direct manifestation of physical dependence and thus develop once physical dependence has been established.
Question 10: In chronic alcoholism and its complications, which of the following is seen?
- A. Wernicke's syndrome
- B. Delirium tremens
- C. Korsakoff psychosis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Wernicke's syndrome**, **Delirium tremens**, and **Korsakoff psychosis** are all well-recognized neurological and psychiatric complications associated with **chronic alcoholism** - Chronic alcohol abuse leads to nutritional deficiencies (especially **thiamine deficiency**) and neurotoxicity, predisposing individuals to these distinct but related conditions *Wernicke's syndrome* - Acute neurological disorder caused by **thiamine deficiency** - Characterized by classic triad: **ataxia**, **ophthalmoplegia**, and **confusion** - If untreated, can progress to **Korsakoff psychosis** *Delirium tremens* - Severe form of **alcohol withdrawal** in individuals with long history of heavy drinking - Symptoms include **delirium**, **severe agitation**, **tremors**, **hallucinations**, and autonomic hyperactivity (**tachycardia**, **hypertension**, **fever**) - Medical emergency requiring prompt treatment *Korsakoff psychosis* - Occurs due to chronic **thiamine deficiency**, often following Wernicke's encephalopathy - Characterized by severe **anterograde and retrograde amnesia**, **confabulation**, and relative preservation of other cognitive functions - Often results in permanent cognitive impairment
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