Dementia diagnosis, functional MRI

The use of neuroimaging techniques in the early and differential diagnosis of dementia

Leonidas Chouliaras & John T. O’Brien

Molecular Psychiatry (2023) of Nature

 

Functional MRI

Functional MRI measures blood flow changes to determine which parts of the brain are engaged when performing a test or at rest and can study brain networks that are functionally connected [76]. The default mode network (DMN) activity has been found to be abnormal in AD [77,78,79]. Resting state fMRI has been used for the differential diagnosis between AD and bvFTD with decreased connectivity in the lateral visual cortical network, lateral occipital and cuneal cortex as well as the auditory system network and angular gyrus seen in bvFTD compared to decreased connectivity in the dorsal visual stream network and lateral occipital and parietal cortex in AD [80]. The disrupted functional connectivity seen in AD has been associated with tau burden and neuroinflammation measured through in vivo PET imaging [81, 82].

 

In DLB, functional connectivity has been used to study symptoms of cognitive fluctuations. Peraza et al. found that the DMN is unaffected in DLB compared to controls but DLB patients show differences in the left fronto-parietal, temporal and sensory motor-network suggesting a potential al role of attention-executive networks in the aetiology of cognitive fluctuations in DLB [83]. Recently, it has been suggested that higher physical activity is associated with greater connectivity in the DMN and may be one of the pathways through which exercise promotes resilience to neurodegeneration [84]. Overall studies in functional MRI in dementia have shown differences in resting state functional connectivity and have pointed to specific networks and regions affected in each dementia, however there seems to be a significant overlap among diagnostic groups and unlikely to be useful clinically.

 

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There is a difference in functional connectivity between AD patients and others.

 

 

행동 변형 전반기 노화(dementia with Lewy bodies; DLB), 비전도형 전두증(bvFTD), 기본 모드 네트워크(DMN)