Summary: Disorders related to progressive cognitive decline constituting an important cause of global death and disability-adjusted life years because conditions are also associated to impairment of several brain functions, psychological and behavioral changes, regardless of economic status. Brain-derived neurotrophic factor (BDNF) is a neurotrophin highly relevant in memory, learning and neuroplasticity processes in adults. The amount of plasma BDNF has been considered to partly reflect its secretion in the brain. Its deficiency is associated with affective disorders and neurodegenerative pathologies such as Alzheimer disease and Parkinson’sdisease.

The aim of this study was to identify quantifiable biomarkers (serum levels of BDNF) and clinical marker (state of depression and anxiety) that allow early detection of cognitive impairment risk. We made an analytic and transversal study with a representative sample (n:307) of the population over 50 years old in the south of Chile (X region). We determine the cognitive condition of the population by applying cognitive functionality tests, such as the minimental status examination (MMSE) test and identify demographic and psychosocial characteristics that constitute impairment cognitive risk. Subsequently, we determined depression status (scale of Yesavage) and anxiety status (Beck inventory), and finally we made a quantitative determination of human BDNF at the blood level using ELISA technique.

Our results revealed that 26.7% of the participants exhibited some degree of cognitive impairment, being higher in women (55.7%) with average age of 70,7. A 18,2% of subjects manifested indicators of depression and 33,2% have a very hight level of anxiety. The correlation analysis revealed a significant positive correlation between MMSE test (p < 0.001) and both BDNF plasma levels (p < 0.001) and education level (p < 0.001) scores. The results additionally indicated a negative correlation between cognitive functions and age range/anxiety state, suggesting low age level/hight level of anxiety in subjects with more pronounced cognitive decline (p < 0.001),. In consistent, the results of our study point towards decreases plasma BDNF levels and hight levels of anxiety in cognitive impairment subjects compared with cognitive normal subjects, which may be due to the early and middle stages of neurodegeneration process.