# Changes in EEG Microstate Dynamics and Cognition Post‐Chemotherapy in People With Breast Cancer

## TL;DR

This study explores how chemotherapy affects brain activity and self-reported cognitive function in breast cancer patients using EEG microstate analysis.

## Contribution

The study provides new evidence of altered brain dynamics post-chemotherapy using a within-cohort design.

## Key findings

- Self-reported cognitive function significantly decreased after chemotherapy.
- EEG microstate durations were significantly longer and less evenly distributed following chemotherapy.
- Microstate D, linked to attention and executive functions, showed increased mean duration after chemotherapy.

## Abstract

Chemotherapy‐related cognitive changes following breast cancer are commonly reported; however, changes in brain dynamics of large‐scale neural networks remain unclear. Using data from the Aerobic exercise and CogniTIVe functioning in women with breAsT cancEr (ACTIVATE) trial, we conducted exploratory analyses to compare self‐reported and objective measures of cognition and applied microstate analysis to resting state (RS) electroencephalography (EEG) data of women with breast cancer before and following chemotherapy treatment.

Data from eight female participants between the ages of 30 and 52 (mean age = 44.8 years, SD = 7.3 years) were analyzed. Cognitive function was assessed using the PROMIS (Patient‐Reported Outcomes Measurement Information System) and the Trail Making Test (TMT). Five minutes of RS eyes‐closed EEG data were also collected. Seven EEG microstates were extracted, and mean microstate duration and occurrence were computed.

Following chemotherapy, there was a significant decrease in the PROMIS score (p = 0.003, d = 1.601), but no significant difference in the TMT score. Overall, microstate durations were significantly longer (p < 0.001, d = 2.837) and less evenly distributed following chemotherapy. The mean duration of microstate D (involved in attention/executive functions) significantly increased following chemotherapy (p = 0.007, d = 1.339). Comparing behavioral and microstate measures that exhibited a large effect size, no significant correlations were observed either before or after chemotherapy.

We observed self‐reported cognitive impairment and disturbed functional dynamics in the RS brain following chemotherapy. This exploratory study provides new evidence using a within‐cohort design showing that changes occur in large scale brain dynamics related to the cognitive effects of chemotherapy.

ClinicalTrials.gov identifier: NCT03277898