Differential Diagnosis in
Psychiatric-Mental Health Across
the Lifespan
Question 1: A 25-year-old female presents with a 2-month history of low mood, anhedonia, and
fatigue. She denies substance use but reports a recent thyroidectomy. What is the
most likely diagnosis?
a) Major Depressive Disorder
b) Adjustment Disorder
c) Hypothyroidism-Induced Mood Disorder
d) Persistent Depressive Disorder
Correct Answer: c) Hypothyroidism-Induced Mood Disorder
Rationale: Post-thyroidectomy hypothyroidism can mimic depressive symptoms
due to metabolic changes affecting mood regulation. Ruling out medical etiology,
such as thyroid dysfunction, is critical before diagnosing primary psychiatric disor-
ders like Major Depressive Disorder or Persistent Depressive Disorder. Adjustment
Disorder is less likely without a clear psychosocial stressor.
Question 2: A 12-year-old male exhibits excessive worry, restlessness, and difficulty concentrat-
ing for 6 months. Symptoms worsen at school. What is the most appropriate
diagnosis?
a) Attention-Deficit/Hyperactivity Disorder (ADHD)
b) Generalized Anxiety Disorder (GAD)
c) Social Anxiety Disorder
d) Obsessive-Compulsive Disorder (OCD)
Correct Answer: b) Generalized Anxiety Disorder (GAD)
Rationale: GAD is characterized by excessive, persistent worry across multiple
domains lasting at least 6 months, often with somatic symptoms like restlessness.
ADHD involves inattention and/or hyperactivity without prominent worry. Social
Anxiety Disorder is specific to social situations, and OCD requires obsessions or
compulsions, which are not described.
Question 3: A 45-year-old male reports auditory hallucinations and disorganized speech for 8
months. He has no history of substance use. What is the most likely diagnosis?
a) Bipolar I Disorder
b) Schizophrenia
c) Brief Psychotic Disorder
d) Delusional Disorder
Correct Answer: b) Schizophrenia
Rationale: Schizophrenia is diagnosed with two or more symptoms (e.g., hallu-
cinations, disorganized speech) persisting for at least 6 months. Brief Psychotic
Disorder lasts less than 1 month, and Delusional Disorder involves non-bizarre
delusions without other psychotic symptoms. Bipolar I Disorder requires manic
episodes, which are not reported.
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,Question 4: A 70-year-old female presents with memory loss, apathy, and social withdrawal.
Her family reports a gradual onset over 2 years. What should be considered first
in the differential diagnosis?
a) Major Depressive Disorder
b) Alzheimer’s Disease
c) Frontotemporal Dementia
d) Normal Aging
Correct Answer: b) Alzheimer’s Disease
Rationale: Gradual memory loss with apathy and social withdrawal in an older
adult suggests a neurodegenerative process like Alzheimer’s Disease. Depression
may cause pseudodementia, but cognitive decline is primary here. Frontotemporal
Dementia typically presents with behavioral changes or language deficits. Normal
aging does not cause significant functional impairment.
Question 5: A 30-year-old male reports insomnia, nightmares, and hypervigilance following a
car accident 3 months ago. What is the most likely diagnosis?
a) Acute Stress Disorder
b) Post-Traumatic Stress Disorder (PTSD)
c) Generalized Anxiety Disorder
d) Adjustment Disorder
Correct Answer: b) Post-Traumatic Stress Disorder (PTSD)
Rationale: PTSD is diagnosed when trauma-related symptoms (e.g., nightmares,
hypervigilance) persist beyond 1 month. Acute Stress Disorder is limited to 3 days
to 1 month post-trauma. GAD involves diffuse worry, and Adjustment Disorder
lacks the specific trauma-related criteria seen here.
Question 6: A 16-year-old female presents with recurrent panic attacks and avoidance of crowded
places. What is the most appropriate diagnosis?
a) Social Anxiety Disorder
b) Panic Disorder
c) Agoraphobia
d) Specific Phobia
Correct Answer: b) Panic Disorder
Rationale: Panic Disorder involves recurrent, unexpected panic attacks with per-
sistent worry about future attacks. Agoraphobia may develop secondary to panic
but requires fear of being unable to escape. Social Anxiety Disorder focuses on
social scrutiny, and Specific Phobia is limited to specific triggers.
Question 7: A 50-year-old male with a history of alcohol use disorder presents with confusion
and ataxia. What is the most likely diagnosis?
a) Delirium Tremens
b) Wernicke’s Encephalopathy
c) Korsakoff’s Syndrome
d) Alcohol-Induced Psychotic Disorder
Correct Answer: b) Wernicke’s Encephalopathy
Rationale: Wernicke’s Encephalopathy, due to thiamine deficiency in chronic al-
cohol use, presents with confusion, ataxia, and oculomotor abnormalities. Delirium
Tremens involves autonomic hyperactivity and tremors. Korsakoff’s Syndrome fea-
tures amnesia, and Alcohol-Induced Psychotic Disorder involves hallucinations or
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, delusions without prominent neurological signs.
Question 8: A 22-year-old female reports binge eating followed by self-induced vomiting twice
weekly for 3 months. What is the most likely diagnosis?
a) Anorexia Nervosa, Binge-Eating/Purging Type
b) Bulimia Nervosa
c) Binge-Eating Disorder
d) Other Specified Feeding or Eating Disorder
Correct Answer: b) Bulimia Nervosa
Rationale: Bulimia Nervosa is characterized by recurrent binge eating and com-
pensatory behaviors (e.g., vomiting) with normal weight. Anorexia Nervosa in-
volves significant weight loss. Binge-Eating Disorder lacks compensatory behaviors,
and Other Specified Feeding or Eating Disorder applies to atypical presentations.
Question 9: A 35-year-old male presents with grandiose delusions and elevated mood for 2 weeks,
followed by a depressive episode. What is the most likely diagnosis?
a) Schizoaffective Disorder
b) Bipolar I Disorder
c) Major Depressive Disorder with Psychotic Features
d) Cyclothymic Disorder
Correct Answer: b) Bipolar I Disorder
Rationale: Bipolar I Disorder involves at least one manic episode, often followed by
depression. Schizoaffective Disorder requires persistent psychotic symptoms during
mood stability. Major Depressive Disorder with Psychotic Features lacks manic
episodes, and Cyclothymic Disorder involves milder, chronic mood fluctuations.
Question 10: A 28-year-old female reports excessive hand-washing and fear of contamination for
1 year. What is the most likely diagnosis?
a) Generalized Anxiety Disorder
b) Obsessive-Compulsive Disorder (OCD)
c) Body Dysmorphic Disorder
d) Illness Anxiety Disorder
Correct Answer: b) Obsessive-Compulsive Disorder (OCD)
Rationale: OCD involves intrusive thoughts (obsessions) and repetitive behaviors
(compulsions) like hand-washing. GAD features diffuse worry without compulsions.
Body Dysmorphic Disorder focuses on perceived physical flaws, and Illness Anxiety
Disorder involves preoccupation with illness without specific rituals.
Question 11: A 60-year-old male presents with irritability, impulsivity, and disinhibited behavior
for 1 year. Neuroimaging shows frontal lobe atrophy. What is the most likely
diagnosis?
a) Alzheimer’s Disease
b) Frontotemporal Dementia
c) Vascular Dementia
d) Major Depressive Disorder
Correct Answer: b) Frontotemporal Dementia
Rationale: Frontotemporal Dementia often presents with behavioral changes (e.g.,
disinhibition, impulsivity) and frontal lobe atrophy. Alzheimer’s Disease primarily
affects memory. Vascular Dementia involves stepwise cognitive decline with vascular
risk factors. Depression may cause irritability but lacks neuroimaging findings.
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