Semi-automated hippocampal segmentation in people with cognitive impairment using an age appropriate template for registration.

BACKGROUND: To evaluate a new semi-automated segmentation method for calculating hippocampal volumes and to compare results with standard software tools in a cohort of people with subjective memory complaints (SMC) and mild cognitive impairment (MCI). METHODS: Data from 58 participants, 39 with SMC (17 male, 22 female, mean age 72.6) and 19 with MCI (6 male, 13 female, mean age 74.3), were analyzed. For each participant, T1-weighted images were acquired using an MPRAGE sequence on a 3 Tesla MRI system. Hippocampal volumes (left, right, and total) were calculated with a new, age appropriate registration template, based on older people and using the advanced software tool ANTs (Advanced Normalization Tools). The results were compared with manual tracing (seen as the reference standard) and two widely accepted automated software tools (FSL, FreeSurfer). RESULTS: The hippocampal volumes, calculated by using the age appropriate registration template were significantly (P < 0.05) more accurate (mean volume accuracy more than 90%) than those obtained with FreeSurfer and FSL (both less than 70%). Dice coefficients for the hippocampal segmentations with the new template method (75.3%) were slightly, but significantly (P < 0.05) higher than those from FreeSurfer (72.4%). CONCLUSION: These results suggest that an age appropriate registration template might be a more accurate alternative to calculate hippocampal volumes when manual segmentation is not feasible.

Relationship of Established Cardiovascular Risk Factors and Peripheral Biomarkers on Cognitive Function in Adults at Risk of Cognitive Deterioration.

BACKGROUND: There is a paucity of information on the role of microvascular and inflammatory biomarkers in cognitive dysfunction. OBJECTIVE: This study sought to evaluate the relationships between established and a number of peripheral biomarkers on cognitive patterns in 108 older adults with memory complaints. METHODS: Participants in the AIBL Active study aged 60 years and older with at least one vascular risk factor and memory complaints completed a neuropsychological test battery and provided cross-sectional health data. Linear regression models adjusted for covariates examined associations between cognitive performance and a panel of vascular risk factors (Framingham cardiovascular scores, hs-CRP, homocysteine, fasting glucose, LDL-cholesterol) and peripheral biomarkers (TNF-α, BDNF, VCAM-1, ICAM-1, PAI-1, CD40L). RESULTS: Higher fasting glucose and homocysteine levels were independent factors associated with poorer performance in Trail Making Test (TMT) B (adjusted ß= 0.40±0.10 and 0.43±0.09, respectively). Increasing homocysteine levels were weakly associated with poorer global cognition and delayed recall (adjusted ß= 0.23±0.10 and -0.20±0.10 respectively). Increasing Framingham cardiovascular scores were related to poorer performance in TMT B (ß â€Š= 0.42±0.19). There was early evidence of associations between increasing plasma TNF-α and poorer TMT B (adjusted ß â€Š= 0.21±0.10) and between increasing BDNF and better global cognition (ß= -0.20±0.09). CONCLUSION: This study provides evidence to support the associations between vascular risk factors (Framingham scores, fasting glucose, and homocysteine) and poorer cognitive functions. Additionally, we measured several peripheral biomarkers to further investigate their associations with cognition. The relationship between TNF-α, BDNF, and cognitive performance in various domains may offer new insights into potential mechanisms in vascular cognitive impairment.