Serum Schiff Bases Are Elevated in Patients with Dementia

Abstract

Hypothesis

Increased oxidative stress may accompany diseases of the central nervous system either as a perpetrator or merely as the result of tissue damage in the course of neurodegeneration. The brain is especially susceptible to damage mediated by reactive oxygen species because it has a high rate of oxygen consumption and contains large amounts of readily oxidizable substrates, such as polyunsaturated fatty acids. Indices of systemic oxidative stress, including serum lipid-peroxidation products, may be greater in dementia than in normal aging.

Methods

Study groups consisted of 30 patients with dementia and 18 healthy age-matched controls. All patients underwent neuropsychological testing and qualified for the study on the basis of history, physical examination, complementary laboratory tests, and brain computed tomography scan. Serum levels were assessed for the following lipid-peroxidation products: conjugated dienes, lipid peroxides, thiobarbituric acid reactive substances, and Schiff bases.

Results

There were two statistically significant differences in serum levels of lipid-peroxidation products between the study groups. Lipid peroxides were significantly lower (0.34 Å 0.09 U532/mL versus 1.12 Å 0.96 U532/mL, p = 0.000055), while Schiff bases were statistically higher (589.4 Å 267.3 AU/mL versus 329.0 Å 107.5 AU/mL, p = 0.000282) in the subjects with dementia. There were statistically significant correlations between all measured products of lipid peroxidation in the controls and between all products of lipid peroxidation except for Schiff bases in the subjects with dementia. Cognitive impairment did not correlate with levels of lipid-peroxidation products. Age correlated negatively with Mini-Mental State Examination score and lipid peroxides in healthy controls.

Conclusion

More final fluorescent products of lipid peroxidation (Schiff bases) were found in subjects with dementia than in healthy controls, implying that oxidative stress is increased in dementia. Our data suggests a decrease in lipid peroxides during normal aging.