Background Brain-derived neurotrophic factor (BDNF) plays a crucial role in the neuronal networking and reorganization. BDNF levels are changed in neurological and psychiatric diseases. We assessed BDNF levels in patients with chronic primary insomnia (PI) and their association with the brain metabolism.

Design and methods We assessed BDNF levels in 27 PI (DSM V criteria) patients (15 males, 56%) and in 14 controls (6 males, 43%). All subjects underwent 18fluorodeoxyglucose positron emission tomography (18F-FDG PET), brain PET with 13N-ammonium in the morning in wakefulness. Brain PET/CT scanning was performed 30 min. after administration of 250 MBq 18F-FDG. The PET images were statistically analyzed by 3D-SSP method (Z-score) using software package Cortex ID.

Results There was no difference in BDNF level in PI patients and control group: 11.9 (8.5; 100) and 12.8 (10.1; 72.8) ng/ml, respectively (p=0,138). We found a weak association between BDNF level and brain metabolism in the left prefrontal medial lobe (ρ=0.57, p=0.02) and right parietal inferior lobe (ρ=0.52, p=0.039). However, there was no association between BDNF level and 13N-ammonium accumulation which indicate the activity of glutamate synthase.

Conclusions Insomnia is not associated with the changes in BDNF levels compared to healthy control subjects, although the relation between brain metabolism and BDNF concentration requires further investigation.

(The study was supported by the Grant of the President of Russian Federation for the Leading Scientific Schools of Russia НШ-5508.2018.7 (agreement № 075-15-2019-161, 23.05.2019).