# Increased central serotonergic activity in patients after an acute ischemic stroke. An EEG study

## TL;DR

This study finds that acute ischemic stroke temporarily alters brain serotonin activity, as shown by EEG measurements, which may help identify patients at risk for depression.

## Contribution

The study introduces early LDAEP measurement as a potential non-invasive biomarker for serotonergic changes after stroke.

## Key findings

- Patients showed lower LDAEP than controls 14 days post-stroke, suggesting increased serotonergic activity.
- LDAEP differences decreased after three months, indicating possible recovery.
- Serotonergic changes were not specific to depression but may be a general effect of stroke.

## Abstract

•14 days after AIS: patients show lower LDAEP than healthy controls, which might indicate increased serotonergic activity.•At 3 months: patient-control LDAEP gap reached trend level, suggesting recovery.•AIS could have led to short-term alterations in serotonergic neurotransmission.

14 days after AIS: patients show lower LDAEP than healthy controls, which might indicate increased serotonergic activity.

At 3 months: patient-control LDAEP gap reached trend level, suggesting recovery.

AIS could have led to short-term alterations in serotonergic neurotransmission.

Acute ischemic stroke (AIS) is often accompanied by functional impairments and post-stroke depression (PSD), affecting ∼30 % of patients. Since central serotonergic dysfunction may contribute to PSD, similar to major depressive disorder, we examined depressive symptoms and serotonergic neurotransmission after AIS using the loudness dependence of auditory evoked potentials (LDAEP), a non-invasive EEG marker.

19 patients with AIS and 18 age-matched healthy participants completed depression questionnaires (BDI, HAMD). LDAEP was assessed within 14 days after AIS and after three months, analyzed with mixed-models ANOVA.

Shortly after AIS, patients showed lower LDAEP compared to controls for all electrodes (AIS M = 0.072 ± 0.077; controls M = 0.133 ± 0.095; p = 0.037), frontal (p = 0.011) and frontocentral (p = 0.027) electrodes. After three months, differences reached trend-level (p = 0.12). Depression scores were higher in patients, but not clinically relevant.

AIS appears to be associated with altered serotonergic neurotransmission, with attenuated LDAEP differences at three months possibly reflecting remission. As depression scores were not clinically relevant, serotonergic changes likely reflect a general AIS effect rather than being specific to PSD.

Early LDAEP measurement may serve as a non-invasive biomarker to identify patients with altered serotonergic functioning and guide interventions, such as SSRI therapy, to reduce PSD risk and improve recovery.