The dual impact of homocysteine and cholesterol on cognitive functions

Abstract

Background There is some debate about the role of cholesterol in cognitive functions. Cholesterol has been accused of its deleterious effect on cognitive functions since decades. Others talked about its beneficial outcomes on cognition. Aim The aim of the study was to find the correlation between total cholesterol (TC) and cognitive functions and if it is homocysteine (Hcy) dependent. Participant and methods We enrolled 41 individuals, aged 55 years old and over. All participants underwent measurement of serum Hcy and TC and other lipid profile components. Assessment of cognitive functions was done by two batteries: Mini-Mental State Exam (MMSE) and Memory Assessment Scale (MAS). Results Forty participants were found to have normal Hcy levels (2.499 ± 0.77 μmol/l). According to the TC level, the participants were divided into three tertiles, in those with the highest TC (>181 mg/dl) there was a direct significant correlation between TC and cgnitive functions as follows: MMSE (P = 0.01), total MAS score (P = 0.04), verbal memory (P = 0.01), and visual memory (P = 0.03). Also, it was noticed that MMSE (P = 0.03), total MAS (P = 0.03), verbal memory (P = 0.04), and visual memory (P = 0.02) had significant positive correlations with high-density lipoprotein cholesterol. Also, MMSE (r = 59, P = 0.00) and total MAS (r = −0.39, P = 0.01) had significant negative correlation with low-density lipoprotein cholesterol. Conclusion High serum TC levels, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol may have protective effects on cognitive functions. However, the authors could not confirm if there is a dual correlation between serum TC and Hcy levels on cognitive functions, as all the participants had normal Hcy levels.