Low plasma thiamine and phosphate in male patients with Parkinson's disease is associated with mild cognitive impairment

Abstract

Thiamine deficiency (TD) and phosphate depletion increase the risk for cognitive disturbances. This study investigates whether plasma levels of thiamine (P-THIAM), thiamine-monophosphate (P-TMP), and phosphate (P-PHOS) are associated with mild cognitive decline (MCI) in patients with Parkinson's disease (PD). This case-control study includes baseline data from a cohort of newly diagnosed patients identified in the New Parkinsonism in Umeå study (NYPUM) (N=75) and an age and sex matched control group (n=24). Mini Nutritional Assessment (MNA-score) and concentrations of P-THIAM, P-TMP, and P-PHOS at baseline were compared between PD patients with mild cognitive impairment (PD-MCI) and PD patients with normal cognition (PD-NC). Neuropsychological assessments of MCI were performed at time of diagnosis. Compared to patients with NC, patients with MCI had lower levels of P-THIAM and P-TMP as well as lower scores on both the Mini Mental State Examination (MMSE) and MNA-screening test. In addition, patients with MCI were older and had more motor problems. The multiple logistic regressions adjusted for age and sex revealed that higher levels of P-THIAM and the MNA-total score were associated with a lower risk of having MCI. Higher MNA-total score and higher P-THIAM and P-PHOS concentrations decreased the risk of MCI in male patients, but not in female patients. The decreased risk of MCI with higher P-TMP levels was lost after adding age and sex to the model. Bivariate correlations between P-PHOS and P-TMP were shown for the total PD population and controls as well as for males with MCI (r=0.533; n=22; p=0.011), but not for males with NC (r=0.314; n=19; p=0.204). An inverse partial correlation (adjusted for age, sex and UPDRS III) was shown for P-THIAM and MNA-total (r=-0.315,p=0.009) and -final (part II) (r=-0.395,p=0.001) score for the PD population (n=75). Higher P-THIAM and P-PHOS concentrations and higher MNA-total score were associated with a lower risk of MCI in male PD patients, findings that indicate that nutritional factors may influence cognitive function in males in the early phase of PD.