Levels of Brain-Derived Neurotrophic Factor (BDNF) and Ciliary Neurotrophic Factor (CNTF) in Blood and Tears of Young and Middle-Aged Patients with Vascular Cognitive Impairment and Depression

Abstract

The influence of neurotrophic factors on the development of vascular cognitive impairment (VCI) and depression has been investigated in a large number of studies. Changes in BDNF levels and its role in the development of cognitive impairment and depression are similar in many ways. However, to date, there is no clear understanding of the mechanisms of BDNF involvement in the development of VCI and depression. Even less data, mainly experimental, are available on the influence of CNTF on the development of cognitive disorders and depression, although its role in their genesis is considered indisputable. The aim of the study was to investigate the levels of BDNF and CNTF in blood and tears of patients with VCI and depression. The study included 324 people admitted to the Moscow Research and Clinical Center for Neuropsychiatry (MRCCN) and healthy controls from January 2017 to March 2023. Participants were divided into four groups: (1) vascular mild cognitive impairment without depression (113 patients, mean age 71.1 ± 9.74 years); (2) vascular dementia without depression (69 patients, mean age 70.7 ± 8.59 years); (3) depression without cognitive impairment (102 patients, mean age 30.7 ± 10.21 years); (4) healthy controls (40 participants, mean age 47.6 ± 22.01 years). All patients underwent neurological and psychiatric examination including Beck depression inventory, Mini International Neuropsychiatric Interview (M.I.N.I.), Montreal Cognitive Assessment Test (MoCA), and Mini-Mental State Examination (MMSE), magnetic resonance imaging (MRI), BDNF and CNTF levels assessment in serum and lacrimal fluid. For statistical analysis we used Mann-Whitney U-test, chi-squared test, Spearman rank correlation. The level of significance p < 0.05. In VCI patients, decreased BDNF levels in blood and tears are observed in dementia. The level of CNTF in tears is significantly lower in MCI and dementia than in healthy individuals of the same age. In people without cognitive impairment and in MCI there is a significant negative correlation of blood BDNF level with age, in dementia this correlation is lost. In depression in young and middle-aged people, there is no correlation of blood BDNF levels with age. In depression, the positive correlation between blood and tear BDNF levels present in healthy young and middle-aged individuals is lost. Blood and tear BDNF levels and their correlations do not differ in patients with unipolar and bipolar depressive disorders. Young and middle-aged depressed patients with depression have elevated levels of CNTF in blood and tears compared to healthy individuals of the same age, but as in non-depressed individuals, there is no significant correlation between CNTF in blood and CNTF in tears. There is no correlation between BDNF and CNTF levels in blood and tears in healthy young and middle-aged individuals and in depressed patients of the same age.