Rationales
1. A 35-year-old patient who smokes cigarettes would like to quit but is nervous because she
typically craves a cigarette approximately every 2 hours. The craving and withdrawal are due to
which neurobiological phenomenon?
A) Desensitization of nicotinic receptors
B) Resensitization of nicotinic receptors
C) Desensitization of muscarinic receptors
D) Resensitization of muscarinic receptors
Correct Answer: Resensitization of nicotinic receptors
Rationale: Nicotine binds to and activates nicotinic acetylcholine receptors (nAChRs). With
repeated exposure, these receptors desensitize. Between cigarettes, the receptors resensitize,
leading to the return of withdrawal symptoms and cravings that drive the timing of cigarette use
. This resensitization is a key mechanism in the maintenance of nicotine dependence.
2. Which neurotransmitter pathway is considered the "pleasure center" of the brain and is a
key site of dopamine release in addiction?
A) Cortico-striatal-thalamic-cortical loop
B) Mesolimbic dopamine pathway
C) Mesocortical dopamine pathway
D) Nigrostriatal pathway
Correct Answer: Mesolimbic dopamine pathway
, Rationale: The mesolimbic dopamine pathway, originating in the ventral tegmental area (VTA)
and projecting to the nucleus accumbens, is the brain's primary reward pathway and is often
referred to as the "pleasure center" . Addictive substances cause a rapid, supraphysiologic spike
in dopamine in this pathway, which drives reinforcement and the compulsive use of substances.
3. A patient has a complex history of substance use and is committed to abstinence. Which
FDA-approved medication has indications for both alcohol and opioid use disorders?
A) Acamprosate
B) Naloxone
C) Naltrexone
D) Disulfiram
Correct Answer: Naltrexone
Rationale: Naltrexone is an opioid antagonist that is FDA-approved for both alcohol and
opioid use disorders. It reduces alcohol cravings by blocking the rewarding effects mediated by
the endogenous opioid system and blocks the euphoric effects of opioids . Acamprosate is only
indicated for alcohol use disorder, and naloxone is primarily used for acute opioid overdose .
4. A patient with moderate Alzheimer's disease is started on memantine. Which of the
following best describes the mechanism of action of this medication?
A) Cholinesterase inhibition
B) NMDA receptor antagonist
C) Dopamine agonist
D) Serotonin reuptake inhibitor
Correct Answer: NMDA receptor antagonist
, Rationale: Memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist . It works by
blocking the NMDA receptor to prevent glutamate, an excitatory neurotransmitter, from
binding. This is thought to protect neurons from excitotoxicity caused by excessive glutamate,
which is implicated in the neurodegeneration of Alzheimer's disease, without affecting normal
neurotransmission .
5. Which of the following medications requires tapering to avoid withdrawal effects when
discontinuing, unlike other medications in its class?
A) Rivastigmine
B) Galantamine
C) Donepezil
D) Memantine
Correct Answer: Donepezil
Rationale: Donepezil requires tapering to avoid withdrawal effects . Rivastigmine and
galantamine do not require tapering . Memantine also does not require tapering. Abrupt
discontinuation of donepezil can lead to a rapid decline in cognitive function.
6. A patient is brought to the emergency department after a suspected overdose. The EKG
shows a widened QRS complex. Which antidepressant is most associated with cardiotoxicity and
this EKG finding?
A) Paroxetine
B) Amitriptyline
C) Phenelzine
D) Isocarboxazid
Correct Answer: Amitriptyline