Objective: We have investigated BDNF levels in pre- and post-treatment serum in patients
with bipolar disorder manic episode.
Methods: The patient group was formed by 29 patients (14 females, 15 males), with
diagnosis of bipolar disorder manic episode and the control group was formed by 29
healthy subjects (14 females, 15 males) who were similar to the patient group, in terms of
age and educational level. Blood samples were collected from the healthy controls and
patients before, and at the 30th day of treatment. Patients included in the study were
evaluated for their autobiography, family history, and sociodemographics, and were
applied the Young Mania Rating Scale (YMRS). After collecting venous blood samples,
serums were separated by centrifugation. Removed serums were incubated at -70 oC for
2-6 [month]s. Based on the sandwich enzyme immunoassay principle, the microElisa system
was applied for the detection of BDNF levels.
In the study, Quantikine Human BDNF Kit was used. The test was performed properly
according to the kit instructions. Due to small sample size and non-normal distribution,
nonparametric tests (Mann-Whitney U and Wilcoxon Signed Ranks Test for continuous
variables, Fisher’s exact test for categoricalvariables) were used. The effects of medications,
age and educational status on pre- and posttreatment changes in BDNF levels were
examined by Kruskall Wallis Test and multiple regression analysis.
Results: Mean age of bipolar patients was 32.62 ± 8.32 (18-45) [year]s and their mean lengt
of education was 8.79 ± 4.08 (0-18) grades. Mean age of control subjects was 33.83 ± 6.65
(17-45) [year]s and mean length of education was 8.31 ± 4.22 (0-17) grades. No significant
difference was found between the two groups in terms of age distribution (p=0.483) and
educational status (p=0.550).The patients were ill for 9.68±8.92 [year]s and, the mean
duration of last manic episode prior to admission was 36.68±29.36 days. Two patients had
their first episode. Previously used medications included valproate in 11 patients, lithium
in 2, carbamazepine in 1 patient and atypical antipsychotics in 5 patients. None of the
patients used a psychotropic medication in the last two [month]s prior to the study. Lithium
was administered to 10 patients and valproate to 17. Two patients did not receive mood
stabilizers. Additionally, a typical antipsychotic was administered to 14 patients, and
atypical antipsychotic to 12 patients.
At baseline, mean BDNF levels were 14.35±5.85 pg/ml in patients and 40.17±9.74 pg/ml in
controls. The difference was statistically significant. A statistically significant reduction of
mean YMRS score was noticed from baseline 35.86±9.36 to 5.18±8.07, after the 30th day of
treatment (p􀀀0.001). Mean BDNF levels were increased from baseline 14.35±5.85 pg/ml to
20.48±7.33 pg/ml after the 30th day, which was also statistically significant (p􀀀0.001).
When the effects of each treatment to the change in YMRS and BDNF level were examined
neither type of the antipsychotic (p=0.111), type of mood stabilizer (p=0.514), the presence
of family history (p=0.512) (kruskall wallis test) nor the severity of manic symptoms
(p=0.705), frequency of manic episodes (p= 0.460) and the length of the disease (p=0.776)
were found to be effecting the BDNF levels.
Conclusions: Lower BDNF levels in manic patients compared to healthy controls suggest
the significance of this neurotrophic factor in mania. However, long-term follow-up studies
with large sample sizes and investigating different periods of bipolar disorder (mania,
depression and euthymic) are needed in order to evaluate the effects of mood stabilizer
and antipsychotic treatments on BDNF levels in mania.