Women at risk for AD show increased parietal activation during a fluency task

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Alzheimer's Disease Research

Background:

• Cognitively normal individuals at high risk for Alzheimer's disease (AD) exhibit altered brain metabolism and functional activation compared to low-risk individuals.
• Previous studies noted increased parietal activation in high-risk subjects during recall tasks, potentially overlapping with verbal fluency activation.

Purpose of the Study:

• To investigate alterations in parietal brain activation during a letter fluency task in cognitively normal individuals at high risk for AD.
• To assess if increased parietal activation is a marker for preclinical Alzheimer's disease.

Main Methods:

• Functional magnetic resonance imaging (fMRI) compared brain activation in cognitively normal women with differing AD risk (family history, APOE status).
• Participants (average age 53) performed a letter fluency task, known to activate frontal and parietal regions.
• Risk groups were matched for age, education, and cognitive performance.

Main Results:

• Both high-risk and low-risk groups displayed similar regional brain activation patterns.
• The high-risk group exhibited significantly greater activation in the left parietal region.
• Letter fluency performance was identical between the high-risk and low-risk groups.

Conclusions:

• Cognitively normal individuals at high risk for AD demonstrate heightened left parietal activation during letter fluency tasks.
• This parietal activation is adjacent to regions identified in previous recall task studies.
• These findings indicate disrupted functional circuits in the left parietal lobe of asymptomatic individuals at increased risk for AD.