# Prefrontal cortex activation patterns in age-related cognitive decline: insights from verbal fluency task

## TL;DR

This study used fNIRS to examine prefrontal cortex activation in older adults with age-related cognitive decline during a verbal fluency task, finding reduced activation linked to cognitive decline.

## Contribution

The study identifies potential fNIRS-based biomarkers for global cognitive decline in ARCD by analyzing prefrontal cortex activation patterns.

## Key findings

- ARCD patients showed reduced prefrontal cortex activation during a verbal fluency task.
- No significant difference in PFC activation was found between ED and non-ED groups.
- Lower MoCA scores correlated with reduced oxy-Hb concentration changes in the left frontal pole.

## Abstract

Age-related cognitive decline (ARCD) is highly prevalent in aging populations and is characterized by progressive declines in cognitive function—particularly executive function (EF), which merits focused investigation. This study aimed to compare prefrontal cortex (PFC) activation patterns between ARCD patients with executive dysfunction (ED) and those with non-executive dysfunction (non-ED) using functional near-infrared spectroscopy (fNIRS) during a verbal fluency task (VFT). It further explored correlations between alterations in PFC activation, the severity of EF impairment, and global cognitive function.

A total of 36 elderly individuals diagnosed with ARCD were recruited for this study. Participants were stratified into the ED group or the non-ED group based on neuropsychological test performance, with 18 individuals in each group. fNIRS was employed during the VFT to assess cortical activity. Additionally, a comprehensive neuropsychological assessment was conducted to evaluate global cognitive function, as well as specific domains related to memory and EF. Correlations between PFC activation, as reflected by changes in oxyhemoglobin (oxy-Hb) concentration and cognitive outcomes were analyzed.

The participants of the ED group were older than those in the non-ED group, and had a higher incidence of type 2 diabetes mellitus than those in the non-ED group. The fNIRS-VFT analysis revealed no activation of the PFC in the ED group (p > 0.05), whereas only minimal activation of the left frontal pole was observed in the non-ED group of ARCD (FDR-corrected p < 0.05). Specifically, activation at Channel 13 (located at the left frontal pole) was statistically higher in the non-ED group than in the ED group at the uncorrected level (p < 0.05); however, this difference became non-significant after FDR correction (p > 0.05). Additionally, the Montreal Cognitive Assessment (MoCA) score was significantly correlated with oxy-Hb concentration changes at Channel 21 (located at the left frontal pole, rs = 0.515, FDR-corrected p < 0.05).

ARCD showed attenuated PFC activation during VFT, with no significant difference between the ED and non-ED groups. The decline in PFC activation was correlated with lower MoCA scores, suggesting that fNIRS-derived PFC activation metrics might serve as a potential biomarker for global cognitive decline in ARCD.