# Cognitive decline and auditory biomarkers: P300 as a diagnostic tool

## TL;DR

The study shows that P300, an auditory brain signal, can help distinguish between mild cognitive impairment and dementia based on differences in signal latency.

## Contribution

The study demonstrates that P300 latency is significantly prolonged in dementia compared to mild cognitive impairment, suggesting its use as a biomarker.

## Key findings

- Dementia patients had significantly longer P300 latencies (395.63ms) compared to those with MCI (355.07ms).
- No significant differences were found in N100, P160, or N200 latencies or in specific amplitude measurements between groups.
- P300 latency is a potential biomarker for assessing cognitive impairment severity.

## Abstract

Over 54% of dementia cases in South America are linked to modifiable factors, emphasizing the need for interventions to prevent or slow its progression. Auditory evoked potentials, electrical signals generated by the auditory system in response to sound stimuli, may serve as valuable diagnostic tools.

This comparative cross‐sectional study, approved by the institutional ethics committee, included clinical, neuropsychological, and audiological assessments, along with the P300 exam. Participants with severe or profound hearing loss, abnormal tympanometry, traumatic brain injury, stroke, or inability to complete the tests were excluded. A trained audiologist conducted the P300 exam using electrodes placed at the frontal, vertex, and parietal midline, referenced to the ears. Tone bursts of 1000 Hz (frequent) and 2000 Hz (rare) were delivered at 90 dB (300 total stimuli), and participants silently counted rare stimuli. Latencies (N100, P160, N200, P300) and amplitudes (N200‐P300, N100‐P160) were measured by trained examiners. P300 was identified as the highest positive peak (250‐500ms) preceded by N100, P160, and N200. Amplitudes were calculated as peak differences between specific waves.

Fifty‐two individuals participated: 22 with mild cognitive impairment (MCI) and 30 with dementia. In the MCI group, 59% were male (n = 13), compared to 27% in the dementia group (n = 8) (p = 0.024). The mean age was 79 years (SD=4) in the MCI group and 80 years (SD=8) in the dementia group (p = 0.274). Educational levels averaged 7 years (SD=5) for MCI and 5 years (SD=4) for dementia (p = 0.15). P300 latency was significantly longer in the dementia group (395.63ms [SD=72.11]) compared to the MCI group (355.07ms [SD=53.06]) (p = 0.034). No significant differences were observed in N100 (p = 0.710), P160 (p = 0.860), or N200 (p = 0.396) latencies or in amplitudes N200‐P300 (p = 0.134) and N100‐P160 (p = 0.748).

Dementia patients exhibit prolonged P300 latencies compared to individuals with MCI. These findings highlight the potential of P300 as a biomarker for distinguishing cognitive impairment severity.