Which disorder is caused by a lack of dopamine?

Which disorder is caused by a lack of dopamine?

• A. Parkinson's
• B. Schizophrenia
• C. Depression
• D. Alzheimer's

Answer: (A)

Dopamine plays a key role in coordinating movement, so a shortage of dopamine in the brain’s movement circuits leads to Parkinson’s disease. Specifically, loss of dopamine-producing neurons in the substantia nigra reduces dopamine in the nigrostriatal pathway, shifting basal ganglia circuits toward movement inhibition. This produces the classic motor symptoms: slowed movements (bradykinesia), stiffness, and resting tremor. Because the core issue is dopamine deficiency, Parkinson’s is the disorder most directly caused by lack of dopamine, and treatments typically aim to boost dopaminergic signaling, such as with L-dopa or dopamine agonists. In contrast, schizophrenia is linked to dysregulated dopamine signaling rather than a simple lack of dopamine, with excess activity in some pathways contributing to symptoms like delusions and hallucinations. Depression involves mood regulation and monoamines more broadly, where dopamine can be reduced in some cases but is not defined by a primary dopamine shortage. Alzheimer’s disease centers on cholinergic deficits and widespread cortical degeneration, not a primary dopamine deficiency.

Dopamine plays a key role in coordinating movement, so a shortage of dopamine in the brain’s movement circuits leads to Parkinson’s disease. Specifically, loss of dopamine-producing neurons in the substantia nigra reduces dopamine in the nigrostriatal pathway, shifting basal ganglia circuits toward movement inhibition. This produces the classic motor symptoms: slowed movements (bradykinesia), stiffness, and resting tremor. Because the core issue is dopamine deficiency, Parkinson’s is the disorder most directly caused by lack of dopamine, and treatments typically aim to boost dopaminergic signaling, such as with L-dopa or dopamine agonists.

In contrast, schizophrenia is linked to dysregulated dopamine signaling rather than a simple lack of dopamine, with excess activity in some pathways contributing to symptoms like delusions and hallucinations. Depression involves mood regulation and monoamines more broadly, where dopamine can be reduced in some cases but is not defined by a primary dopamine shortage. Alzheimer’s disease centers on cholinergic deficits and widespread cortical degeneration, not a primary dopamine deficiency.