Abstract
Reductions in BDNF activity have shown associations with depressed mood. Other evidence has demonstrated that the BDNF Val66Met polymorphism (rs6265) appears to reduce neural plasticity. A limited number of studies have investigated the influence of these genetic polymorphisms in insomnia. The present study sought to confirm the presence of associations between BDNF Val66Met polymorphism (rs6265) occurrence in normal sleepers and those with insomnia.
The study subjects consisted of a patient group (n = 199) complaining of insomnia and a control group (n = 51). Each subject was clinically interviewed using questions taken from the Brief Insomnia Questionnaire. After the interview, the subjects were asked to complete the Insomnia Severity Index, The Hamilton Depression Rating Scale, and the Montreal Cognitive Assessment Test. An overnight polysomnography test was also administered. Blood samples were collected for genetic study.
The insomnia patients showed a greater prevalence of heterozygous (A/G) VAL/MET polymorphism than the normal controls (p = ≤ 0.0001). This finding confirmed that this genetic polymorphism, which impairs BDNF activity, is an important correlate of disturbed sleep. Further, the finding of significantly greater (p = ≤ 0.0001) depression scores among the insomnia group suggested that BDNF is an important factor in the development of depressive symptoms.
The results of the present study indicate that BDNF gene polymorphism plays a prominent role in the variation of symptoms among insomnia patients and, further, that this polymorphism is strongly related to the severity of depression.
•Genetic factors are important contributors to sleep processes, sleep disorders and cognitive functioning.•Insomnia is one of the commonest sleep disorders and there is a lack of satisfactory objective testing instruments for assessing cognitive deficits in insomnia patients.•Genetic polymorphisms which impair BDNF function was found in patients with insomnia and were significantly greater than in normal control subjects•Associations between the BDNF polymorphism and poor performance on the cognitive tests, polysomnograhic parameters, and severity of insomnia and depression were detected.