Structural connectivity changes in unilateral hearing loss.

Network connectivity, as mapped by the whole brain connectome, plays a crucial role in regulating auditory function. Auditory deprivation such as unilateral hearing loss might alter structural network connectivity; however, these potential alterations are poorly understood. Thirty-seven acoustic neuroma patients with unilateral hearing loss (19 left-sided and 18 right-sided) and 19 healthy controls underwent diffusion-weighted and T1-weighted imaging to assess edge strength, node strength, and global efficiency of the structural connectome. Edge strength was estimated by pair-wise normalized streamline density from tractography and connectomics. Node strength and global efficiency were calculated through graph theory analysis of the connectome. Pure-tone audiometry and word recognition scores were used to correlate the degree and duration of unilateral hearing loss with node strength and global efficiency. We demonstrate significantly stronger edge strength and node strength through the visual network, weaker edge strength and node strength in the somatomotor network, and stronger global efficiency in the unilateral hearing loss patients. No discernible correlations were observed between the degree and duration of unilateral hearing loss and the measures of node strength or global efficiency. These findings contribute to our understanding of the role of structural connectivity in hearing by facilitating visual network upregulation and somatomotor network downregulation after unilateral hearing loss.

Effect of sex on the APOE4-aging interaction in the white matter microstructure of cognitively normal older adults using diffusion-tensor MRI with orthogonal-tensor decomposition (DT-DOME).

The influence of the apolipoprotein E ε4 allele (APOE4) on brain microstructure of cognitively normal older adults remains incompletely understood, in part due to heterogeneity within study populations. In this study, we examined white-matter microstructural integrity in cognitively normal older adults as a function of APOE4 carrier status using conventional diffusion-tensor imaging (DTI) and the novel orthogonal-tensor decomposition (DT-DOME), accounting for the effects of age and sex. Age associations with white-matter microstructure did not significantly depend on APOE4 status, but did differ between sexes, emphasizing the importance of accounting for sex differences in APOE research. Moreover, we found the DT-DOME to be more sensitive than conventional DTI metrics to such age-related and sex effects, especially in crossing WM fiber regions, and suggest their use in further investigation of white matter microstructure across the life span in health and disease.

Development of the Story Telling Examination for Early Mild Cognitive Impairment (Pre-Mild Cognitive Impairment) Screening.

INTRODUCTION: Cognitive function prior to mild cognitive impairment (MCI) has become a burgeoning interest. Tools used to detect this early period before MCI are being pilot-tested. This study aimed to develop a new test to detect pre-MCI and to examine its content validity and feasibility. METHODS: The Story Telling Examination for Early MCI Screening (STEEMS), an audio cognitive test, was developed. It covers ten cognitive domains, e.g., executive function, language fluency, abstract reasoning. Face and content validity were examined by experts in geriatric psychiatry and psychology. The content validity index was 1.00. STEEMS comprised 12 items with 2-4 types of scoring. The tool was further examined in 16 pilot samples for feasibility among healthy participants having no cognitive impairment (Montreal Cognitive Assessment [MoCA] test score ≥25, Mini-Cog ≥3) and no depressive symptoms (Geriatric Depression Scale <6). RESULTS: The 16 healthy older individuals aged 59-73 years, mean age was 65.06 ± 4.07 years, were predominantly males (68.8%). STEEMS scores ranged from 10 to 25, with a mean of 18.38 (SD = 4.2). Thirteen percent obtained 100% correct on the STEEMS, 63% scored 68-92% correct, and 25% scored 40-60% correct. The pre-MCI scores are illustrated by a bell curve's graphical depiction, suggesting a normal distribution probability distribution. Correlation between STEEMS and MoCA test scores was observed. STEEMS showed to be feasible for early elderly or late adults as being brief and easy to understand. The time spent to administer was predictably less than 7 min. DISCUSSION/CONCLUSION: STEEMS could potentially serve as a tool for pre-MCI screening. Further study and investigation in a larger population are required.

Fornix Integrity Is Differently Associated With Cognition in Healthy Aging and Non-amnestic Mild Cognitive Impairment: A Pilot Diffusion Tensor Imaging Study in Thai Older Adults.

Damage to the fornix leads to significant memory impairment and executive dysfunction and is associated with dementia risk. We sought to identify if fornix integrity and fiber length are disrupted in mild cognitive impairment (MCI) and how they associate with cognition. Data from 14 healthy older adult controls (HCs) and 17 subjects with non-amnestic MCI (n-aMCI) were analyzed. Diffusion tensor imaging (DTI) at 1.5 Tesla MRI was performed to enable manual tracing of the fornix and calculation of DTI parameters. Higher fractional anisotropy of body and column of the fornix was associated with better executive functioning and memory, more strongly in the HC than in the n-aMCI group. Fornix fiber tract length (FTL) was associated with better executive function, more strongly in the n-aMCI than in the HC group, and with better memory, more strongly in the HC than in the n-aMCI group. These results highlight a decline in the contributions of the fornix to cognition in n-aMCI and suggest that maintenance of fornix FTL is essential for sustaining executive functioning in people with n-aMCI.