Point-of-care examination of visual evoked potentials in acutely hospitalized schizophrenia patients
J. Hubenak, L. Miščík RamešováIntroduction
Research on visual evoked potentials (VEP) offers the possibility of finding electrophysiological markers of schizophrenia (SCH). VEP research has so far been limited to specialized laboratories. The development of a new portable device for the VEP measurement has brought the possibility of examining acutely ill patients. Previous research on VEP in SCH has shown a decrease in the amplitude of the P300 wave and a prolongation of the P300 latency as a promising endophenotype of SCH.
Objectives
The aim was to measure VEP in hospitalized SCH patients and verify whether previously P300 connected findings also apply in this population. The mobile VEP device also allows for the determination of the speed of the motor response (i.e. reaction time, RT) to a visual stimulus. The secondary aim was to evaluate the relationship between physical parameters and immunological indicators (i.e. ratios of blood element counts from the blood count) with VEP values.
Methods
VEPs were measured in SCH patients hospitalized at the Dept. of Psychiatry of the Univ Hos in Hradec Králové. VEPs were also obtained from age and sex matched controls. The amplitude and latency of the P300 were evaluated. The motor response (button press) RT to a visual stimulus was measured. Other obtained values were: Body Mass Index (BMI), Positive and Negative Syndrome Scale (PANSS), Brief negative Symptom Scale (BNSS), Clinical Global Impressions-Severity (CGI-S) scales, B-CATS neuropsychological battery (containing tests TMT-A, TMT-B, Digit symbol, Animal naming), blood count.
Results
Data from 60 patients and 60 healthy controls (HC) have been obtained so far. The P300 had a (p = 0.18) reduced amplitude, prolonged latency, and RT in SCH (both p < 0.001). RT increased faster (slowed down) in SCH in relation to age compared to HC. Moderate and weak correlations (Spearman’s rho) were achieved between cognitive test scores and VEP values. BMI was only weakly correlated with P300 amplitude, but not significantly correlated with other VEP values. Blood counts were also not significantly correlated with VEP values. BNSS and PANSS total scores both achieved moderate correlations with RT and with the difference in RT and latency. Olanzapine medication equivalent achieved only weak correlations with VEP. Correlations of VEP with CGI-S were only weak.