Cerebral Cortex
March 7, 2011
Elizabeth C. Mormino, Andre Smiljic, Amynta O. Hayenga et al.
349 citations
Beta-amyloid deposition, a hallmark of Alzheimer's disease, is also common in cognitively normal older adults. Using Pittsburgh compound-B PET imaging, the study found that greater beta-amyloid burden in normal controls is associated with altered functional connectivity within the default mode network during rest. Connectivity decreased in regions critical for episodic memory, including posteromedial cortex, ventral medial prefrontal cortex, and angular gyrus, while increases appeared in dorsal and anterior medial prefrontal and lateral temporal cortices. The decreases align with known vulnerability of memory-related areas in Alzheimer's disease, and the increases may reflect compensatory mechanisms.
Brain
April 9, 2013
Winston Chiong, Stephen M. Wilson, Mark D’Esposito et al.
234 citations
Large-scale brain networks coordinate human behavior, and their anatomy helps explain how neurodegenerative diseases progress. Alzheimer's disease targets the default mode network, while behavioral variant frontotemporal dementia targets the salience network. The default mode network is active when healthy people consider personal moral dilemmas, yet Alzheimer's patients respond normally to these dilemmas, whereas frontotemporal dementia patients give abnormally utilitarian responses. This discrepancy may arise because the salience network modulates default mode network activity.
medRxiv
February 7, 2025
Andrew G. Breithaupt, Georges Naasan, Suzanne M. Shdo et al.
preprint
Psychosis is a common and burdensome symptom in neurodegenerative diseases. Analyzing 283 autopsy-confirmed cases, delusions were linked to atrophy in the right temporal lobe and bilateral frontal lobes, especially when persecutory or paranoid, implicating circuits for reward, emotion, self-awareness, and executive function. Misidentification delusions correlated with right ventral temporal-occipital atrophy, disrupting visual stream processing. No consistent atrophy patterns emerged with hallucinations. Damage to these brain regions predisposes individuals to delusions across different syndromes and pathologies, suggesting shared mechanisms between neurologic and psychiatric disorders.