Neurobiology and Genetics of Mental Disorders Practice Questions

Q: Which neurotransmitters are related to schizophrenia pathology?

Dopamine and Serotonin. ### Explanation **Correct Option: A (Dopamine and Serotonin)** The pathophysiology of Schizophrenia is primarily explained by the **Dopamine Hypothesis** and the **Serotonin Hypothesis**. 1. **Dopamine:** Excessive dopaminergic activity in the **mesolimbic pathway** is linked to positive symptoms (hallucinations, delusions), while decreased activity in the **mesocortical pathway** is linked to negative symptoms (apathy, withdrawal). 2. **Serotonin (5-HT):** The role of serotonin is evidenced by the efficacy of **Atypical Antipsychotics** (e.g., Clozapine, Risperidone), which act as 5-HT2A receptor antagonists. Serotonin modulates dopamine release; blocking 5-HT2A receptors in the cortex increases dopamine release, helping alleviate negative symptoms. **Why other options are incorrect:** * **Option B & C (Acetylcholine):** While cholinergic systems are involved in cognitive functions and smoking behaviors in schizophrenia, they are not considered primary drivers of the core psychotic pathology compared to dopamine and serotonin. * **Option D (Norepinephrine):** Norepinephrine is more significantly associated with **Mood Disorders** (Depression and Mania) and Anxiety/Panic disorders rather than the primary etiology of schizophrenia. **NEET-PG High-Yield Pearls:** * **Glutamate Hypothesis:** Another emerging theory suggests **NMDA receptor hypofunction** contributes to schizophrenia (supported by the fact that Phencyclidine/PCP, an NMDA antagonist, mimics schizophrenia symptoms). * **Pathway Specificity:** * *Mesolimbic:* Positive symptoms. * *Mesocortical:* Negative symptoms. * *Nigrostriatal:* Site for Extrapyramidal Side Effects (EPS). * *Tuberoinfundibular:* Site for Hyperprolactinemia. * **Drug of Choice:** For treatment-resistant schizophrenia, **Clozapine** is the gold standard (acts on D2 and 5-HT2A).

Q: Gustatory hallucinations can be associated with which of the following conditions?

Temporal lobe epilepsy. **Explanation:** **Temporal lobe epilepsy (TLE)** is the correct answer because gustatory (taste) and olfactory (smell) hallucinations are classic sensory manifestations of auras originating in the temporal lobe, specifically the uncus or the insular cortex. These are often described as unpleasant, metallic, or "burnt" tastes and are hallmark features of **complex partial seizures** (focal seizures with impaired awareness). **Analysis of Options:** * **Post-traumatic stress disorder (PTSD):** While PTSD involves "flashbacks" and intrusive memories, these are typically visual or auditory re-experiences of trauma rather than isolated gustatory hallucinations. * **Grand mal epilepsy (Tonic-Clonic Seizures):** These involve generalized electrical activity across the entire brain leading to immediate loss of consciousness. While a focal seizure (like TLE) can progress to a grand mal seizure, the specific sensory aura (gustatory) is localized to the temporal lobe. * **Alcohol use disorder:** Alcohol withdrawal is most commonly associated with **visual hallucinations** (e.g., seeing small animals or insects) or tactile hallucinations (formication). **High-Yield Clinical Pearls for NEET-PG:** * **Olfactory Hallucinations:** Most commonly associated with **Uncinate fits** (a type of TLE). Always rule out organic brain lesions (like tumors) in the temporal lobe if a patient presents with new-onset foul smells. * **Visual Hallucinations:** Most common in **Organic Brain Syndromes** (Delirium, Dementia) and substance withdrawal. * **Auditory Hallucinations:** The most common type in **Schizophrenia** (specifically third-person voices). * **Tactile Hallucinations:** Frequently seen in **Cocaine use** (Cocaine bugs/Magnan’s sign) and Alcohol withdrawal.

Q: The characteristic symptom of organic psychosis is:

Hallucination. **Explanation:** Organic psychosis refers to psychotic symptoms (hallucinations or delusions) that are a direct physiological consequence of a general medical condition (e.g., epilepsy, endocrine disorders, or metabolic disturbances). **Why Hallucination is the correct answer:** Hallucinations, particularly **visual hallucinations**, are the hallmark and most characteristic feature of organic psychosis. While functional psychoses (like schizophrenia) typically present with auditory hallucinations, organic causes frequently manifest as vivid visual, tactile, or olfactory hallucinations. The presence of hallucinations in a clear or clouded sensorium (delirium) is a primary diagnostic indicator that the psychosis has an underlying biological or structural etiology. **Analysis of Incorrect Options:** * **B. Depression:** While depression can occur secondary to medical conditions (e.g., hypothyroidism), it is a mood disturbance rather than a defining feature of "psychosis." * **C. Transient Delusion:** Delusions do occur in organic states, but they are often fragmented and less systematized than those in schizophrenia. However, hallucinations remain more characteristic and diagnostically significant for an organic diagnosis. * **D. Anxiety:** Anxiety is a non-specific symptom found in almost all psychiatric and many medical disorders; it lacks the diagnostic specificity for organic psychosis. **NEET-PG High-Yield Pearls:** * **Visual Hallucinations = Think Organic:** Always rule out medical causes (e.g., delirium, alcohol withdrawal, or temporal lobe epilepsy) when a patient presents with visual hallucinations. * **Sensorium:** In organic psychosis (unlike schizophrenia), there is often an impairment of consciousness, orientation, or memory. * **Formication:** A specific tactile hallucination (feeling of insects crawling on skin) is a classic organic symptom seen in cocaine toxicity and alcohol withdrawal (Delirium Tremens).

Q: Déjà vu is most commonly associated with which condition?

Temporal lobe epilepsy. **Explanation:** **Déjà vu** (French for "already seen") is a disturbance of memory where a person has the subjective feeling that a current novel experience has been lived through before. **1. Why Temporal Lobe Epilepsy (TLE) is the correct answer:** While déjà vu can occur in healthy people, it is most clinically significant as a **pathognomonic aura** of Temporal Lobe Epilepsy. It occurs due to abnormal electrical discharges in the medial temporal lobe, specifically the **hippocampus and amygdala**, which are responsible for memory processing and emotional coloring. In TLE, it is often accompanied by other "dreamy states," such as *déjà entendu* (already heard) or *jamais vu* (familiarity felt as strange). **2. Analysis of Incorrect Options:** * **A. Normal individuals:** Although approximately 60-70% of the healthy population experiences occasional déjà vu (often triggered by stress or fatigue), it is not considered a "condition" or a diagnostic hallmark in this context. In exams, when asked for an associated *medical condition*, TLE is the primary choice. * **C. Psychosis:** While patients with schizophrenia may experience distortions of reality, déjà vu is not a core feature of psychosis. Psychotic symptoms are more typically characterized by delusions and hallucinations rather than paroxysmal memory disturbances. **3. NEET-PG High-Yield Pearls:** * **Jamais vu:** The false feeling of unfamiliarity with a very well-known situation (the opposite of déjà vu). * **Aura of TLE:** Includes déjà vu, epigastric rising sensations (most common), olfactory hallucinations (uncinate fits), and intense fear. * **Localization:** Déjà vu is specifically linked to the **non-dominant** temporal lobe. * **Paramnesia:** Déjà vu is classified as a "phenomenon of recognition" or a type of paramnesia (distortion of memory).

Q: The characteristic symptom of organic psychosis is:

Transient delusion. **Explanation:** Organic psychosis refers to psychotic symptoms arising from an underlying medical condition, substance use, or brain injury (e.g., delirium, dementia, or metabolic encephalopathy). **Why "Transient Delusion" is the correct answer:** In organic psychosis, the clinical picture is often fluctuating and unstable. Unlike functional psychoses (like Schizophrenia), where delusions are typically systematized, persistent, and complex, delusions in organic states are usually **fragmentary, fleeting, and transient**. Because the underlying cause is a physiological disturbance affecting consciousness or cognition, the patient lacks the cognitive integration to maintain a complex, long-term delusional system. **Analysis of Incorrect Options:** * **A. Hallucination:** While common in organic states (especially visual hallucinations in delirium), they are not as "characteristic" a differentiator as the nature of the delusions. Hallucinations are also hallmark features of functional disorders like Schizophrenia. * **B. Depression:** This is a mood disturbance. While it can occur secondary to organic brain disease (e.g., post-stroke depression), it is not a defining feature of a psychotic state. * **D. Anxiety:** Anxiety is a non-specific symptom found across almost all psychiatric and many medical disorders; it lacks the diagnostic specificity for organic psychosis. **High-Yield Clinical Pearls for NEET-PG:** * **Visual Hallucinations:** If a patient presents with new-onset visual hallucinations, always rule out an **organic cause** first. * **Clouding of Consciousness:** This is the hallmark of Delirium (the most common organic psychosis). * **Age of Onset:** Psychosis starting after age 40 should be considered organic until proven otherwise. * **Functional vs. Organic:** Functional psychosis (Schizophrenia) usually features auditory hallucinations and "systematized" delusions in a clear sensorium.

Q: Which of the following is true regarding a phantom limb?

Follows amputation. **Explanation:** **Phantom Limb** is a sensory phenomenon where an individual continues to experience sensations (such as touch, pressure, or pain) in a limb or organ that has been surgically removed or lost through trauma. 1. **Why Option B is Correct:** The underlying mechanism is **neuroplasticity**. Following **amputation**, the primary somatosensory cortex undergoes reorganization. The cortical area previously dedicated to the missing limb is "invaded" by neighboring sensory maps (e.g., the face area). When the face is touched, the brain misinterprets the signals as coming from the missing limb. It is reported by nearly 80-100% of amputees. 2. **Why Other Options are Incorrect:** * **Option A (Leprosy):** While leprosy involves peripheral nerve damage and auto-amputation of digits, the term "phantom limb" specifically refers to the vivid sensation of a missing body part, which is not a hallmark feature of leprosy-related sensory loss. * **Option C (Psychiatric Illness):** Phantom limb is a **neurological/neuropsychiatric** phenomenon, not a primary psychiatric illness like schizophrenia or conversion disorder. However, it can lead to psychological distress. * **Option D (Filariasis):** Filariasis causes lymphedema (elephantiasis), where the limb becomes enlarged but remains attached. There is no loss of the limb to trigger phantom sensations. **High-Yield Clinical Pearls for NEET-PG:** * **Phantom Limb Pain:** A subtype where the sensations are painful (burning, cramping). It is often treated with **Mirror Box Therapy**, which helps "retrain" the brain. * **Pharmacotherapy:** Neuropathic pain agents like **Gabapentin, Pregabalin, or TCAs** (Amitriptyline) are first-line treatments. * **Distinction:** Do not confuse this with **"Stump Pain,"** which occurs at the actual site of the surgical scar due to neuromas or local tissue damage.

Q: Which drug effect mimics schizophrenia?

Phencyclidine. **Explanation:** The correct answer is **Phencyclidine (PCP)**. **1. Why Phencyclidine is correct:** Phencyclidine (PCP), also known as "angel dust," is a non-competitive antagonist at the **NMDA (N-methyl-D-aspartate) glutamate receptor**. Unlike other psychotomimetic drugs (like LSD), PCP is unique because it mimics **both the positive symptoms** (hallucinations, delusions, thought disorder) and **negative symptoms** (social withdrawal, flattened affect, cognitive impairment) of schizophrenia. This observation led to the "Glutamate Hypothesis" of schizophrenia, suggesting that NMDA receptor hypofunction plays a central role in the pathogenesis of the disorder. **2. Why the other options are incorrect:** * **Barbiturates:** These are CNS depressants that act as GABA-A receptor mimetics. Overdose leads to sedation, respiratory depression, and coma, rather than a schizophrenic-like state. * **Cocaine:** Cocaine increases synaptic dopamine by inhibiting reuptake. While it can induce "Cocaine Psychosis" (characterized by paranoid delusions and tactile hallucinations like formication), it primarily mimics the **positive symptoms** only and lacks the negative/cognitive symptom profile of schizophrenia. * **Levodopa:** A dopamine precursor used in Parkinson’s disease. While it can cause drug-induced psychosis (visual hallucinations) due to increased dopamine in the mesolimbic pathway, it does not replicate the full clinical spectrum of schizophrenia as closely as PCP. **3. NEET-PG High-Yield Pearls:** * **Ketamine:** Like PCP, it is an NMDA antagonist and can also induce dissociative anesthesia and schizophrenic-like symptoms. * **Dopamine Hypothesis:** Traditional antipsychotics work by blocking D2 receptors, primarily targeting positive symptoms. * **Glutamate Hypothesis:** Explains why NMDA antagonists (PCP/Ketamine) produce a more "complete" model of schizophrenia than dopaminergic agents.

Question 1

Which neurotransmitters are related to schizophrenia pathology?

Accepted Answer

Dopamine and Serotonin

Answer

Acetylcholine and Dopamine

Answer

Acetylcholine and Serotonin

Answer

Dopamine and Norepinephrine (NA)

Question 2

Gustatory hallucinations can be associated with which of the following conditions?

Accepted Answer

Temporal lobe epilepsy

Answer

Post-traumatic stress disorder (PTSD)

Answer

Grand mal epilepsy

Answer

Alcohol use disorder

Question 3

What is a characteristic feature of a frontal lobe tumor?

Accepted Answer

Antisocial behavior

Answer

Abnormal gait

Answer

Aphasia

Answer

Distractibility

Question 4

The characteristic symptom of organic psychosis is:

Accepted Answer

Hallucination

Answer

Depression

Answer

Transient delusion

Answer

Anxiety

Question 5

Déjà vu is most commonly associated with which condition?

Accepted Answer

Temporal lobe epilepsy

Answer

Normal individuals

Answer

Psychosis

Answer

All of the above

Question 6

The characteristic symptom of organic psychosis is:

Accepted Answer

Transient delusion

Answer

Hallucination

Answer

Depression

Answer

Anxiety

Question 7

Which of the following features is NOT typically seen in an organic mental disorder in a 24-year-old man?

Accepted Answer

Normal intelligence

Answer

Impaired memory

Answer

Decreased consciousness

Answer

Vomiting

Question 8

Which of the following is true regarding a phantom limb?

Accepted Answer

Follows amputation

Answer

Occurs in leprosy

Answer

Follows a psychiatric illness

Answer

After filariasis

Question 9

Which drug effect mimics schizophrenia?

Accepted Answer

Phencyclidine

Answer

Barbiturates

Answer

Cocaine

Answer

Levodopa

Question 10

Which of the following can cause organic amnestic syndrome?

Accepted Answer

Hyperglycemia

Answer

Multiple sclerosis

Answer

Hypoglycemia

Answer

Hypoxia

Neurobiology and Genetics of Mental Disorders — MCQs

Neurobiology and Genetics of Mental Disorders — MCQs

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