Serum ethanolamine plasmalogens improve detection of cognitive impairment among elderly with high excretion levels of urinary myo-inositol: A cross-sectional study.

ABSTRACT

BACKGROUND: Several reports have implicated myo-inositol (MI) in myelin formation. We hypothesized that MI is involved in this process through facilitating the biosynthesis of ethanolamine plasmalogens (PlsEtns), which are the major component of myelin membranes, and essential for myelin formation and function. Excessive MI urinary excretion possibly causes PlsEtn deficiency, leading to demyelinating diseases including dementia. METHODS: We examined the association between cognitive impairment, serum levels of PlsEtn, and baseline levels of urinary MI excretion, in the enrollment of 55 memory clinic outpatients and 107 cognitively normal elderly. RESULTS: Serum PlsEtns were independently associated with cognitive impairment, and significantly reduced in memory clinic outpatients, especially in those with high urinary MI, as compared to normal elderly. On the other hand, there was no direct association between urinary MI and cognitive impairment, but urinary MI was significantly associated with serum hemoglobin A1c and amyloid ß 1-40. The interaction between PlsEtn and urinary MI for cognitive impairment was statistically confirmed, and their combined usage improved diagnosis of cognitive impairment. CONCLUSIONS: We proposed the involvement of MI and PlsEtn in cognitive impairment pathology. In conclusion, serum PlsEtn may be useful in detecting cognitive decline among elderly with hyperglycemia.