Correlation between myelin basic protein levels in cerebrospinal fluid and motor speed in patients with schizophrenia

Abstract

Alterations in the white matter have been implicated in schizophrenia. Myelin basic protein (MBP), a component of the myelin sheath, in the cerebrospinal fluid (CSF) has been suggested as a biomarker for white matter damage in demyelinating diseases. This prompted us to examine the CSF-MBP levels in patients with schizophrenia. We analyzed the CSF-MBP levels in 152 patients with schizophrenia and 117 age- and sex-matched controls. A significant positive correlation between age and CSF-MBP levels was observed both in the patients (p < 0.001) and controls (p = 0.014). No significant difference was observed in the CSF-MBP levels between the two groups. However, among a subsample of the patients (N = 32), a significantly negative correlation was observed between CSF-MBP and age-adjusted motor speed score of the brief assessment of cognition in schizophrenia (ρ = -0.59, p < 0.001). Further, among patients who underwent diffusional magnetic resonance imaging of the brain (N = 27), the CSF-MBP levels showed a significantly negative correlation with the mean kurtosis value in the right temporo-parietal region (p < 0.001). Our results suggest that the CSF-MBP level has limited utility as a diagnostic marker; however, higher CSF-MBP levels are associated with poorer motor speed, which may be associated with regional white matter damage in the brain in patients with schizophrenia.

Keywords: cerebrospinal fluid; demyelination; motor speed; myelin basic protein; schizophrenia.

FIGURE 1

Dot plots with the MBP levels in the CSF samples of controls and patients with schizophrenia. The horizontal bar represents the mean values of each group. The dotted line represents the upper limit of normal, which is the mean of the controls plus two times the standard deviation (=98.6 pg/mL). CSF, Cerebrospinal fluid; MBP, Myelin basic protein.

FIGURE 2

Scatter plots with age on the x‐axis and the CSF‐MBP levels on the y‐axis. The maximum and minimum ages of the participants were 65 and 15, respectively. The middle line is the regression line, and the upper and lower dashed lines represent 95% CI. CI, Confidence interval; CSF, Cerebrospinal fluid; MBP, Myelin basic protein.

FIGURE 3

Scatter plots of the data of the patients with schizophrenia with the CSF‐MBP levels on the x‐axis and the motor speed scores of BACS on the y‐axis. The middle line is the regression line, and the upper and lower dashed lines represent 95% CI. The maximum and minimum ages of the participants were 56 and 20, respectively. BACS, The brief assessment of cognition in schizophrenia; CI, Confidence interval; CSF, Cerebrospinal fluid; MBP, Myelin basic protein.

FIGURE 4

Relationships between the MK value and CSF‐MBP level in the patients with schizophrenia. A significant negative correlation was observed between the MK value and CSF‐MBP level in the right temporo‐parietal region (indicated by arrows in the three right images). The maximum and minimum ages of the participants were 57 and 20, respectively. The background image is the “avg152T1” image, regarded as one of the anatomically standardized images in the SPM8. “R” is right, and “L” is left. CSF, Cerebrospinal fluid; MBP, Myelin basic protein; MK, Mean kurtosis.