Association Between sTREM2, an Immune Biomarker of Microglial Activation, and Aging-Related Brain Volume Changes in Community-Dwelling Older Adults: A 7-Year Follow-Up Study

Abstract

BackgroundThis study aimed to investigate the association between serum levels of soluble triggering receptor expressed on myeloid cells 2 (sTREM2), a soluble form of an innate immune receptor expressed on the microglia, and brain volume in older adults.MethodsThe survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 596 residents. Serum sTREM2 level measurements, brain MRI, Mini-Mental State Examination (MMSE), and clinical dementia rating (CDR) were performed at Time 1 (2009–2011). Follow-up brain MRI, MMSE, and CDR were performed at Time 2 (2016–2017). The interval between Time 1 and Time 2 was approximately 7 years. Sixty-nine participants (16 men, mean age 72.69 ± 3.18 years; 53 women, mean age 72.68 ± 4.64 years) completed this study. We analyzed the correlation between serum sTREM2 levels (Time 1) and brain volume (Time 1, Time 2, and Time 1–Time 2 difference) using voxel-based morphometry implemented with Statistical Parametric Mapping.ResultsParticipants in this study had lower MMSE and higher CDR scores 7 years after the baseline evaluation. However, analyses at the cluster level by applying multiple comparison corrections (family wise error; P < 0.05) showed no correlation between serum sTREM2 levels and volume of different brain regions, either cross-sectional or longitudinal.ConclusionSerum sTREM2 level could not serve as an immune biomarker of aging-related volume changes in brain regions closely related to cognitive function in older adults aged 65 years and above.

Association between cortisol and aging-related hippocampus volume changes in community-dwelling older adults: a 7-year follow-up study

“…This was a longitudinal study conducted in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and above, as reported previously [ 4 – 9 ]. Kurokawa-cho is in the northwestern Saga Prefecture and is a rural town that is somewhat cut-off from urban areas.…”

“…On the same day, at Saga University, all samples were centrifuged. Next, the serum was extracted, transferred to a container, and immediately stored at -80 °C [ 8 , 9 ].…”

“…The intra- and inter-assay coefficients of variation were 6.97% and 13.63%, respectively. The baseline survey also included hypertension and metabolic status assessments, such as body mass index (BMI) and recording the history of diabetes and dyslipidemia [ 8 , 9 ].…”

“…Three-dimensional T1-weighted structural images were acquired for each participant using a field echo three-dimensional method (TR: 21 ms, TE: 5.5 ms, flip angle: 20°, field of view: 240 × 240 mm, matrix: 256 × 256, slice thickness: 1.5 mm, number of slices: 124). The examination conditions were kept the same for all participants and followed a standardized procedure [ 8 , 9 ].…”

“…Nabeta et al reported that higher salivary cortisol levels were associated with a later depressive state in older healthy women. Additionally, we attempted to develop peripheral biomarkers related to modifiable risk factors to prevent dementia by analyzing the association between peripheral biomarkers and brain volumes [ 8 , 9 ].…”