A lesion of the frontal lobe is most consistent with which symptom?

• A. Visual hallucinations
• B. Aphasia
• C. Ataxia
• D. Disinhibition syndrome

Answer: (D)

Damage to the frontal lobe disrupts the brain’s ability to regulate behavior and impulses. The orbitofrontal and ventromedial prefrontal circuits normally restrain inappropriate actions and maintain social norms. When these areas are damaged, the result is disinhibition: impulsivity, socially inappropriate behavior, poor judgment, and personality changes. This pattern is classic for frontal lobe injury, making disinhibition the most consistent symptom.

Visual hallucinations usually point to posterior cortical or temporal lobe pathology rather than frontal dysfunction. Aphasia can occur with damage to language areas in the dominant frontal lobe (such as Broca’s area), but not all frontal lesions produce language deficits. Ataxia arises from cerebellar dysfunction, not the frontal lobe.