Question

Which of the following best describes the dopamine hypothesis of schizophrenia?

• A. Excess dopamine activity in the mesolimbic pathway leads to positive symptoms
• B. Reduced dopamine in the nigrostriatal pathway leads to cognitive symptoms
• C. Excess serotonin activity causes hallucinations
• D. Dopamine deficiency in the mesolimbic pathway leads to delusions

Hint:

The dopamine hypothesis is the classic explanation for schizophrenia. It says that the symptoms of this disorder are linked to abnormal dopamine signalling in specific nerve pathways of the brain.

Answer 1

The Correct Option is A

Step 1: What is the dopamine hypothesis of schizophrenia?
The dopamine hypothesis proposes that abnormal dopamine activity in specific brain pathways underlies the symptoms of schizophrenia. The key word is pathway specificity.

Step 2: Understand the mesolimbic pathway.
The mesolimbic pathway runs from the ventral tegmental area to the limbic system. Excess dopamine activity here is linked to positive symptoms of schizophrenia such as hallucinations, delusions, and disorganized thinking. All antipsychotic drugs block D2 receptors in this pathway to reduce these symptoms.

Step 3: Evaluate the wrong options.
Option 2 is wrong because it says nigrostriatal pathway leads to cognitive symptoms, which is inaccurate. The nigrostriatal pathway is associated with movement (Parkinsonism when blocked by antipsychotics). Option 3 is wrong because the hypothesis is about dopamine, not serotonin. Option 4 reverses the logic: the mesolimbic pathway shows EXCESS, not deficiency, in schizophrenia.

Step 4: Confirm Option 1.
Excess dopamine activity in the mesolimbic pathway produces the positive symptoms of schizophrenia. This is the central statement of the dopamine hypothesis.

Step 5: Quick memory tip.
Mesolimbic excess = positive symptoms. Mesocortical deficit = negative/cognitive symptoms.

Answer: Option (1) — Excess dopamine activity in the mesolimbic pathway leads to positive symptoms