The Relation of Circulating Levels of Leptin with Cognition in Patients with Alzheimer's Disease

To investigate the relation of circulating levels of leptin with cognition in Alzheimer's disease (AD) patients.

Thirty patients meeting the clinical diagnostic criteria for AD, and twenty-five healthy controls were enrolled into the study. At baseline, all patients underwent standing height, weight measurements, and waist circumference (in centimeters) using a standard scale. Body mass index (BMI) was then calculated as weight (in kilograms). A single 5-ml fasting blood sample was obtained from each patient. All subjects were evaluated by Turkish version of Mini Mental State Examination (MMSE), Clinical Dementia Rating (CDR) and Global Deterioration Scale (GDS).

The mean age of patients and controls were 72.33±10.11 and 67.20±8.95, respectively. There was not any significant difference between age of the patients and the controls (p=0.054). Both patient and control groups consisted of mostly women (60% and 56% respectively). The mean waist circumferences (WC) of patients and controls were 95.46±10.87 and 97.76±10.07, respectively and was not statistically different (p=0.424). The mean serum leptin levels in patients and controls were 5.49±4.06 ng/dL 5.71±4.45 ng/dL, respectively. Leptin levels were not statistically different between patients and controls (p=0.84). The mean MMSE scores of AD patients and controls were 17±6.54 and 27.32±2.15 respectively, and AD patients had significantly lower MMSE scores than the controls (p=0.000). The mean BMI of patients and controls were 25.72±3.98 and 27.92±3.08 respectively. The BMI of controls were higher than patients and there was statistically significant difference between two groups (p=0.029). In the patient group, there were no correlations between leptin levels and age (p=0.067), BMI (p=0.098), WC (p=0.113), MMSE (p=0.203), CDR (p=0.519) and GDS (p=0.587). Similarly in control group leptin levels were not correlated with BMI (p=0.718), WC (p=0.755) and MMSE (p=0.859).

In the present study, we could not find any relation between blood leptin levels and cognition in AD patients.