Biomarkers.

Area of Science:

• Neuroscience
• Cognitive Neurology
• Neuroimaging

Background:

• Posterior cortical atrophy (PCA) is characterized by visuospatial, visuoperceptual, and attention deficits.
• The dorsal attention network (DAN) is crucial for attention and other cognitive functions, but its relationship with other brain networks in PCA is unclear.

Purpose of the Study:

• To investigate the functional connectivity of the dorsal attention network (DAN) in PCA patients.
• To examine the relationship between DAN connectivity, gray matter volume, and memory functions in PCA.

Main Methods:

• Compared functional connectivity within and between brain networks in 57 PCA patients and 60 cognitively unimpaired (CU) individuals using the CONN toolbox.
• Analyzed connectivity of the DAN, including frontal eye field (FEF) and intraparietal sulcus (IPS), and its interaction with frontoparietal, visual, and default mode networks (DMN).
• Used multivariate linear regression to assess associations between network connectivity, gray matter volume, and clinical test scores.

Main Results:

• PCA patients showed reduced within-network connectivity in the DAN, particularly in the IPS and overall network, compared to CU individuals.
• Increased between-network connectivity was observed between the frontoparietal network and the DAN (FEF and entire network) in PCA patients.
• Lower DAN within-network connectivity correlated with a trend for reduced gray matter volume and significantly lower scores on memory tests (AVLT-RCP, WMS III-digit span backward).

Conclusions:

• Functional connectivity within and between networks involving the DAN is disrupted in PCA.
• These disruptions are associated with memory impairments and, to a lesser extent, gray matter volume loss in PCA.
• The DAN's connectivity is altered in PCA, impacting cognitive functions beyond attention.