Neurobiology and Genetics of Mental Disorders Practice Questions

Q: Specific genetic conditions account for a proportion of Autism Spectrum Disorder (ASD) cases. Which of the following are known to be associated with ASD ? I. Tuberous sclerosis II. Fragile X syndrome III. Prader-Willi syndrome IV. Patau syndrome Select the correct answer using the code given below :

I and II. ***I and II*** - Both **Tuberous sclerosis** and **Fragile X syndrome** are well-established genetic conditions with a strong association with Autism Spectrum Disorder (ASD). - Tuberous Sclerosis Complex (TSC) is a genetic disorder that causes **benign tumors** to grow in the brain and other organs, and approximately **40-50% of individuals with TSC also have ASD**. Fragile X syndrome is the **most common inherited cause of intellectual disability** and a leading known **single-gene cause of ASD**, with about **25-50% of affected males** meeting the diagnostic criteria for ASD. *I and III* - While Tuberous sclerosis is strongly associated with ASD, **Prader-Willi syndrome** has a less consistent and well-defined relationship with ASD despite some overlapping behavioral features. - Prader-Willi syndrome is characterized by **hyperphagia (insatiable appetite)**, intellectual disability, and behavioral problems, but the autistic-like features may represent a behavioral phenocopy rather than true ASD. *II and III* - **Fragile X syndrome** is strongly associated with ASD, but **Prader-Willi syndrome** is not considered a primary or well-established genetic cause of ASD. - While intellectual disability and behavioral difficulties can be present in both, their underlying genetic mechanisms and core features differ significantly regarding ASD classification. *I and IV* - **Tuberous sclerosis** is clearly linked to ASD, but **Patau syndrome (Trisomy 13)** is not associated with ASD. - Patau syndrome is a severe chromosomal disorder characterized by **multiple congenital abnormalities** and **profound developmental delays**, often leading to early mortality. The severe nature of the condition and high infant mortality rate preclude typical ASD presentation.

Q: The following is suggestive of an organic cause of behavioral symptoms:

Prominent visual hallucinations. ***Prominent visual hallucinations*** - The presence of prominent **visual hallucinations** is highly suggestive of an organic etiology, such as **delirium**, dementia, or substance intoxication/withdrawal. - While visual hallucinations can rarely occur in primary psychiatric disorders like schizophrenia, they are typically less prominent and often accompanied by a more complex symptom profile. *Auditory hallucinations* - **Auditory hallucinations**, particularly third-person or command hallucinations, are a hallmark symptom of primary psychotic disorders like **schizophrenia**. - While they can occur in organic conditions, they are less specific to organic causes than visual hallucinations. *Formal thought disorder* - **Formal thought disorder**, characterized by disorganized speech (e.g., loose associations, tangentiality, incoherence), is a core feature of **schizophrenia** and other primary psychotic disorders. - While cognitive impairment from organic causes can affect thought processes, a clinically significant formal thought disorder is more commonly associated with primary psychiatric illness. *Delusion of guilt* - A **delusion of guilt** is a false, fixed belief that one is responsible for a bad outcome or crime, often seen in severe **depressive episodes with psychotic features** or severe forms of obsessive-compulsive disorder. - This symptom is typical of primary psychiatric disorders rather than being a primary indicator of an organic cause.

Q: A 48 year old male incurred a road traffic accident leading to a brain lesion. Now the patient feels euphoric, laughs uncontrollably, jokes & makes puns. Which of the following brain parts may be involved?

Prefrontal cortex. ***Prefrontal cortex*** - Lesions in the **prefrontal cortex**, particularly the **orbital frontal cortex**, can lead to disinhibition, euphoria, inappropriate jocularity (witzelsucht), and lack of insight. - This region is critical for **executive functions**, social behavior, and emotional regulation, and damage can result in personality changes like those described. *Parietal lobe* - The **parietal lobe** is primarily involved in processing sensory information, spatial orientation, and navigation. - Damage typically results in sensory deficits, **neglect syndromes**, or **apraxia**, not euphoria or exaggerated humor. *Cerebellum* - The **cerebellum** is mainly responsible for motor control, coordination, and balance. - Lesions typically cause **ataxia**, dysarthria, and gait disturbances, not changes in mood or personality as described. *Occipital lobe* - The **occipital lobe** is the primary visual processing center of the brain. - Damage to this area typically leads to **visual field deficits**, cortical blindness, or visual agnosias, and is not associated with behavioral changes like euphoria or inappropriate humor.

Q: The psychiatric disorder most likely to be associated with epilepsy is:

Depression. ***Depression*** - **Depression** is the most commonly recognized psychiatric comorbidity in patients with epilepsy, affecting a significant percentage of individuals. - The link is multifactorial, involving shared neurobiological pathways, the psychosocial impact of living with a chronic illness, and potential side effects of **antiepileptic drugs (AEDs)**. *Psychosis* - While **psychosis** can be associated with epilepsy (e.g., postictal psychosis, interictal psychosis), it is less common than depression. - The prevalence of psychosis in epilepsy typically ranges between 5-10%, whereas depression is much higher. *Mania* - **Mania** and bipolar disorder can occur in individuals with epilepsy, but they are less prevalent than depression. - Some AEDs, such as **topiramate** or **levetiracetam**, may rarely induce manic symptoms. *Insomnia* - **Insomnia** is a common sleep disturbance in the general population and can be more prevalent in individuals with epilepsy. - However, it is a symptom or a sleep disorder rather than a primary psychiatric disorder in the same vein as depression or psychosis.

Q: Subcortical dementia is seen in all except:

Alzheimer's disease. ***Alzheimer's disease*** - Alzheimer's disease is categorized as a **cortical dementia**, primarily affecting the cerebral cortex. - It is characterized by early impairment in **memory**, language, and executive functions due to cortical atrophy and **neurofibrillary tangles** and amyloid plaques primarily in cortical regions. *HIV related dementia* - HIV-associated neurocognitive disorders (HAND) often manifest as a **subcortical dementia**, affecting white matter and deep gray matter structures. - Patients typically present with prominent **psychomotor slowing**, executive dysfunction, and apathy, rather than profound memory deficits in early stages. *Parkinson's disease* - Parkinson's disease, particularly when dementia develops, is considered a **subcortical dementia**. - It involves pathology in the **basal ganglia** and other subcortical structures, leading to deficits in executive function, attention, and visuospatial skills. *Multiple sclerosis* - Cognitive impairments in multiple sclerosis often present as a **subcortical dementia**, particularly involving processing speed, attention, and executive functions. - This is due to **demyelination** and axonal damage primarily affecting white matter tracts and subcortical gray matter.

Q: What is the concordance rate for schizophrenia in monozygotic twins?

50%. ***50%*** - The **concordance rate** for schizophrenia in **monozygotic (identical) twins** is approximately **50%**. - This high concordance rate indicates a strong **genetic predisposition** but also highlights the role of **environmental factors**, as it is not 100%. *1%* - A 1% risk is closer to the **general population prevalence** of schizophrenia, not the concordance rate in monozygotic twins. - This low percentage would significantly underestimate the genetic component observed in twin studies for schizophrenia. *10%* - A 10% concordance rate is a significant increase over the general population risk but is still substantially lower than what has been consistently found in studies of monozygotic twins. - This percentage might be more aligned with the risk for first-degree relatives or dizygotic twins, not identical twins. *0.10%* - A 0.10% concordance rate is an extremely low figure, far below the actual observed rate for monozygotic twins. - Such a low percentage would suggest virtually no genetic influence on schizophrenia, which contradicts extensive research findings.

Q: Which of the following behavioral problems would suggest an organic brain lesion?

Visual hallucinations. ***Visual hallucinations*** - While visual hallucinations can occur in primary psychiatric disorders, they are *more commonly* associated with **organic brain lesions** (e.g., tumors, delirium, dementia, substance withdrawal) compared to auditory hallucinations. - They often indicate **neurological dysfunction** and warrant further investigation for an underlying physical cause. *Auditory hallucinations* - **Auditory hallucinations** are a hallmark symptom of **psychotic disorders** such as **schizophrenia**, and are less specific for organic brain lesions unless they are complex and multimodal. - While possible in organic conditions (e.g., temporal lobe epilepsy), they are more strongly linked to functional psychiatric illness than visual hallucinations. *Formal thought disorder* - **Formal thought disorder** (e.g., loosening of associations, word salad, tangentiality) is a core symptom of **schizophrenia** and other primary psychotic disorders. - It is a disturbance in the *form* of thought rather than its content, and is primarily a **psychiatric phenomenon**. *Depression* - **Depression** is a common mood disorder with diverse etiologies, including psychosocial stressors and neurochemical imbalances, but it is not typically indicative of a focal **organic brain lesion**. - Although depression can coexist with neurological conditions, it is not a direct behavioral symptom of a localized brain injury.

Q: Following are predispositions of Alzheimer's disease except:

Blood type O. ***Blood type O*** - There is currently **no established scientific evidence** linking blood type O directly to an increased risk or predisposition for Alzheimer's disease. - Genetic factors associated with Alzheimer's, such as the **APOE4 allele**, are not correlated with blood type. *Down's syndrome* - Individuals with **Down's syndrome** (Trisomy 21) have three copies of chromosome 21, which includes the **APP (amyloid precursor protein) gene**. - This overexpression of APP leads to increased production of **amyloid-beta plaques**, predisposing them to early-onset Alzheimer's-like pathology. *Head trauma* - A history of **moderate to severe head trauma**, particularly if repeated, has been identified as a significant risk factor for developing Alzheimer's disease. - Head injuries can trigger mechanisms that lead to **amyloid plaque deposition** and **tau tangle formation**. *Low education group* - A lower level of education is associated with an **increased risk of Alzheimer's disease**, possibly due to differences in **cognitive reserve**. - Higher education is thought to build greater cognitive reserve, making the brain more resilient to the pathological changes of Alzheimer's.

Q: Post contusional syndrome includes:

Headache. ***Headache*** - **Headache** is the **most common and characteristic symptom** of **post-concussion syndrome (PCS)**, present in up to 90% of cases. - Typically described as tension-type or migraine-like headaches that persist for weeks to months after mild traumatic brain injury. - This is a **core diagnostic feature** of PCS according to ICD-10 (F07.2) and DSM-5 criteria. - Among the given options, this is the **most definitive symptom** of post-concussion syndrome. *Delirium* - **Delirium** is an acute confusional state with fluctuating consciousness, impaired attention, and cognitive dysfunction. - This is **NOT a feature of post-concussion syndrome**, which involves persistent symptoms in clear consciousness. - Delirium may occur immediately after severe traumatic brain injury but is not part of the chronic post-concussional syndrome picture. - Post-concussion syndrome involves cognitive difficulties (memory, concentration) but not delirium. *Nausea & vomiting* - **Nausea** can occur as part of post-concussion syndrome, particularly when associated with vestibular dysfunction or migraine-like headaches. - However, it is **less characteristic and less persistent** than headache, and is not present in all cases. - While recognized in ICD-10 criteria for PCS, nausea is not as defining or universal as headache. - Vomiting is less common in chronic PCS compared to acute concussion. *All of the options* - This is incorrect because **delirium is NOT a feature of post-concussion syndrome**. - While headache is the hallmark symptom and nausea can occur, delirium represents acute brain dysfunction, not the chronic syndrome. - PCS is characterized by persistent somatic (headache, dizziness), cognitive (concentration, memory problems), and psychological (irritability, anxiety) symptoms in clear consciousness.

Q: Organic Mental Disease is indicated by

Perseveration of speech. ***Perseveration of speech*** - **Perseveration** involves the persistent repetition of a word, phrase, or idea despite the absence of the stimulus or the need to respond differently, which is a classic symptom of **organic brain dysfunction**. - This symptom often occurs in conditions like **dementia**, **traumatic brain injury**, or other neurological disorders affecting cognitive flexibility and executive function. *Delusion* - **Delusions** are firmly held false beliefs that are not amenable to change in light of conflicting evidence, which are hallmark symptoms of **psychotic disorders** like schizophrenia. - While organic conditions can sometimes present with delusions, they are more typically associated with primary psychiatric illnesses rather than being a core indicator of organic mental disease alone. *Flight of ideas* - **Flight of ideas** is a rapid shifting of ideas with only superficial associative connections between them, often seen in **manic episodes** of bipolar disorder. - It reflects a disturbance in the speed and flow of thought, but not necessarily a primary organic brain structural or functional deficit. *Incoherence* - **Incoherence** (or "word salad") refers to speech that is incomprehensible because there is no logical or meaningful connection between words or phrases, a feature commonly found in **psychotic disorders**. - While extreme cognitive disorganization can occur in advanced organic disorders, incoherence itself is more characteristic of thought disorganization in functional psychoses.

Question 1

Specific genetic conditions account for a proportion of Autism Spectrum Disorder (ASD) cases. Which of the following are known to be associated with ASD ?
I. Tuberous sclerosis
II. Fragile X syndrome
III. Prader-Willi syndrome
IV. Patau syndrome

Select the correct answer using the code given below :

Accepted Answer

I and II

Answer

I and III

Answer

II and III

Answer

I and IV

Question 2

The following is suggestive of an organic cause of behavioral symptoms:

Accepted Answer

Prominent visual hallucinations

Answer

Auditory hallucinations

Answer

Formal thought disorder

Answer

Delusion of guilt

Question 3

A 48 year old male incurred a road traffic accident leading to a brain lesion. Now the patient feels euphoric, laughs uncontrollably, jokes & makes puns. Which of the following brain parts may be involved?

Accepted Answer

Prefrontal cortex

Answer

Parietal lobe

Answer

Cerebellum

Answer

Occipital lobe

Question 4

The psychiatric disorder most likely to be associated with epilepsy is:

Accepted Answer

Depression

Answer

Psychosis

Answer

Mania

Answer

Insomnia

Question 5

Subcortical dementia is seen in all except:

Accepted Answer

Alzheimer's disease

Answer

HIV related dementia

Answer

Parkinson's disease

Answer

Multiple sclerosis

Question 6

What is the concordance rate for schizophrenia in monozygotic twins?

Accepted Answer

50%

Answer

1%

Answer

10%

Answer

0.10%

Question 7

Which of the following behavioral problems would suggest an organic brain lesion?

Accepted Answer

Visual hallucinations

Answer

Auditory hallucinations

Answer

Formal thought disorder

Answer

Depression

Question 8

Following are predispositions of Alzheimer's disease except:

Accepted Answer

Blood type O

Answer

Down's syndrome

Answer

Head trauma

Answer

Low education group

Question 9

Post contusional syndrome includes:

Accepted Answer

Headache

Answer

Delirium

Answer

Nausea & vomiting

Answer

All of the options

Question 10

Organic Mental Disease is indicated by

Accepted Answer

Perseveration of speech

Answer

Delusion

Answer

Flight of ideas

Answer

Incoherence

Neurobiology and Genetics of Mental Disorders — MCQs

Neurobiology and Genetics of Mental Disorders — MCQs

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