**Question:** Subcortical dementia is seen in all except -

A. Alzheimer's disease
B. Frontotemporal dementia
C. Lewy body dementia
D. vascular dementia

**Core Concept:** Subcortical dementia refers to a group of dementias characterized by symptoms related to damage in the subcortical areas of the brain, such as the basal ganglia, thalamus, and corpus callosum. These dementias are associated with impairment in motor function, gait, and memory, as well as other cognitive functions.

**Why the Correct Answer is Right:** Alzheimer's disease (A) primarily affects the cortex, leading to cortical dementia, which is characterized by memory impairment and cortical function deficits. Frontotemporal dementia (B) is also primarily associated with cortical involvement. Lewy body dementia (C) is characterized by α-synuclein pathology in the cortex and subcortical structures, resulting in a combination of cortical and subcortical dysfunction. Vascular dementia (D) is caused by vascular lesions in the brain, typically affecting both the cortex and subcortical regions.

**Why Each Wrong Option is Incorrect:** Alzheimer's disease (A) primarily affects the cortex, leading to cortical dementia. Frontotemporal dementia (B) is also primarily associated with cortical involvement. Lewy body dementia (C) is characterized by α-synuclein pathology in the cortex and subcortical structures, resulting in a combination of cortical and subcortical dysfunction. Vascular dementia (D) is caused by vascular lesions in the brain, typically affecting both the cortex and subcortical regions.

**Clinical Pearl:** Subcortical dementia should be suspected in patients presenting with motor symptoms, gait abnormalities, and cognitive decline. In these cases, ruling out cortical dementias (Alzheimer's, frontotemporal dementia) and vascular dementia is crucial to accurately diagnose the correct subcortical dementia subtype (Lewy body dementia, cerebral amyloid angiopathy, etc.) and initiate appropriate management strategies.