Background: Gamma glutamyltransferase (GGT) plays a role in cellular glutathione uptake, which is an important element of antioxidant mechanisms. An increase in serum GGT is thought to be an early and sensitive marker of oxidative stress. Oxidative stress has a role in the pathogenesis of Alzheimer's disease (AD). The aim of this study was to investigate the GGT levels in AD.

Method: In this cross-sectional study, 132 patients with AD (mean age: 74.1 ± 7.4, female 62.9%) and 158 age- and gender-matched normal controls (mean age: 74.5 ± 6.3, female 67.1%) were evaluated. For cognitive assessment, MMSE and clock drawing tests were performed; DSM-IV and NINCDS-ADRDA criteria were used. Serum GGT, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase concentrations were determined.

Results: Median (min-max) GGT levels were 18 (9–70) in AD group and 17 (5–32) in normal controls. Mann-Whitney U test showed that GGT levels were significantly higher in AD patients (p = 0.012). Linear regression analysis revealed AD was an independent correlate of elevated GGT levels. Hypertension, diabetes mellitus, total cholesterol, and low density lipoprotein cholesterol were not associated with GGT levels.

Conclusion: GGT levels were increased significantly in AD patients. To evaluate the role of GGT as a marker of oxidative stress in AD, further studies are needed.