Episodic memory in mild cognitive impairment inversely correlates with the global modularity of the cerebral blood flow network

• Published in: Psychiatry research. Neuroimaging Vol. 282; pp. 73 - 81
• Main Authors: Sánchez-Catasús, Carlos A, Willemsen, Antoon, Boellaard, Ronald, Juarez-Orozco, Luis Eduardo, Samper-Noa, Juan, Aguila-Ruiz, Angel, De Deyn, Peter Paul, Dierckx, Rudi, Medina, Yasser Iturria, Melie-Garcia, Lester
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 30.12.2018
• Subjects: Aged; Brain - blood supply; Brain - diagnostic imaging; Brain - physiopathology; Brain connectivity; Brain Mapping - methods; Cerebral blood flow; Cerebrovascular Circulation - physiology; Cognitive Dysfunction - diagnostic imaging; Cognitive Dysfunction - physiopathology; Episodic memory; Female; Global network modularity; Humans; Male; Memory, Episodic; Middle Aged; Mild cognitive impairment; Single-photon emission computed tomography (SPECT); Tomography, Emission-Computed, Single-Photon - methods; Brain connectivity; Cerebral blood flow; Mild cognitive impairment; Episodic memory; Single-photon emission computed tomography (SPECT); Global network modularity
• ISSN: 0925-4927; 1872-7506
• DOI: 10.1016/j.pscychresns.2018.11.003

•The global modularity of the CBF network increases in MCI.•Episodic memory and patient contribution to global modularity inverse correlate.•Connectivity analysis based on SPECT confirms brain connectivity alterations in MCI. Cerebral blood flow (CBF) SPECT is an interesting methodology to study brain connectivity in mild cognitive impairment (MCI) since it is accessible worldwide and can be used as a biomarker of neuronal injury in MCI. In CBF SPECT, connectivity is grounded in group-based correlation networks. Therefore, topological metrics derived from the CBF correlation network cannot be used to support diagnosis and prognosis individually. However, methods to extract the individual patient contribution to topological metrics of group-based correlation networks were developed although not yet applied to MCI patients. Here, we investigate whether the episodic memory of 24 amnestic MCI patients correlates with individual patient contributions to topological metrics of the CBF correlation network. We first compared topological metrics of the MCI group network with the network corresponding to 26 controls. Metrics that showed significant differences were then used for the individual patient contribution analysis. We found that the global network modularity was increased while global efficiency decreased in the MCI network compared to the control. Most importantly, we found that episodic memory inversely correlates with the patient contribution to the global network modularity, which highlights the potential of this approach to develop a CBF connectivity-based biomarker at the individual level.