Serial visual evoked potential recordings in geriatric psychiatry

Area of Science:

• Neuroscience
• Ophthalmology
• Geriatrics

Background:

• Dementia, including Alzheimer's disease (AD) and multi-infarct dementia (MID), significantly impacts cognitive function in the elderly.
• Visual evoked potentials (VEPs) are objective electrophysiological measures sensitive to visual pathway integrity.

Purpose of the Study:

• To longitudinally assess changes in VEP parameters in patients with senile dementia of the Alzheimer type (SDAT), MID, functional psychiatric illness, and healthy elderly controls.
• To investigate the diagnostic utility of VEP latency differences between flash and pattern reversal stimuli in differentiating dementia subtypes.

Main Methods:

• Serial VEP recordings (flash and pattern reversal) were conducted every six months for two years in four groups: SDAT, MID, functional psychiatric illness, and elderly controls.
• Key VEP components (P2, P100) latency and amplitude were measured.
• The flash P2-pattern reversal P100 latency difference was calculated for each participant.

Main Results:

• No significant VEP parameter changes over time were observed in any group.
• A significant trend of increasing flash P2 latency and flash P2-pattern reversal P100 latency difference was noted in the SDAT group over time.
• The flash P2-pattern reversal P100 latency difference was significantly longer in SDAT and MID groups compared to functional psychiatric illness patients.
• This latency difference was significantly greater in the SDAT group than in the control group.

Conclusions:

• VEP measures, particularly the flash P2-pattern reversal P100 latency difference, show potential in distinguishing SDAT and MID from functional psychiatric illness in the elderly.
• Longitudinal VEP analysis in SDAT reveals a progressive delay in flash P2 latency, suggesting ongoing visual pathway changes.