Cortical atrophy in senile dementia of the Alzheimer type is mainly due to a decrease in cortical length.

Area of Science:

• Neuroscience
• Neuropathology
• Gerontology

Background:

• Senile dementia of the Alzheimer type (SDAT) is a progressive neurodegenerative disorder.
• Quantifying brain structural changes is crucial for understanding SDAT pathogenesis.

Purpose of the Study:

• To investigate the relationship between mental impairment severity and cortical morphometry in normal aging and SDAT.
• To determine if cortical length or thickness is more affected in SDAT.

Main Methods:

• Prospective study of mentally normal elderly subjects and SDAT patients.
• Blessed Test Score (BTS) used for mental impairment assessment.
• Semiautomatic image analysis of cortical area and perimeter from coronal sections.
• Calculation of cortical length and thickness.

Main Results:

• Blessed Test Score (BTS) significantly correlated with temporal cortex area (r=0.7695, P=0.003) and length (r=0.7421, P=0.006).
• No significant correlation found between BTS and temporal cortex thickness (r=0.559, P=0.059).
• Pathologic confirmation of SDAT or normal aging in 12 postmortem cases.

Conclusions:

• Reduced temporal cortex length is a key factor in cortical atrophy in SDAT.
• Results support a hypothesis of column-selective atrophy in SDAT.
• Findings necessitate consideration of selective atrophy in microscopic data interpretation for SDAT.