Tardive dyskinesia linked to decreased BDNF in schizophrenia patients
MedWire News: Tardive dyskinesia (TD) is associated with reduced levels of brain-derived neurotrophic factor (BDNF) in patients with schizophrenia, researchers have found.
Writing in the journal Neuroscience Letters, Ya Qin Yu (Jilin University, Changchun, China) and colleagues explain that although the pathophysiology of TD - involuntary, abnormal movements that may occur during or after long-term treatment with neuroleptic drugs - is unclear, "a neurodegenerative hypothesis has been proposed."
As BDNF is critical for the maintenance of functional neurons, the team investigated whether TD is associated with altered levels of the neurotrophin in schizophrenia patients.
They studied 364 chronic schizophrenia patients, with an average illness duration of 27 years, and 323 mentally healthy controls who were matched for age and gender. Of the schizophrenia patients, 129 had TD and 235 did not have the movement disorder.
Blood samples from the participants were assessed for BDNF levels using enzyme-linked immunosorbent assay.
The severity of abnormal movements and positive and negative symptoms was assessed using the Abnormal Involuntary Movement Scale (AIMS) and the Positive and Negative Syndrome Scale (PANSS).
The researchers found that BDNF levels were significantly lower in patients with TD than in those without, at 8.8 versus 10.5 ng/ml.
This difference remained significant after accounting for gender, age, education, hospitalizations, body mass index, and neuroleptic treatment (typical versus atypical antipsychotics), dosage, and years of exposure.
Furthermore, BDNF level was significantly lower in both the TD and non-TD patients compared with controls (11.9 ng/ml).
In schizophrenia patients, lower serum BDNF levels were significantly associated with higher PANSS negative symptom scores, but BDNF levels were not correlated with AIMS scores.
These findings indicate that "decreased BDNF may play an important role in the pathophysiology of TD as a type of neurodegeneration or an adaptive response to neuroleptic induced up-regulation of the dopamine systems," the researchers conclude.
They add that "the relationship between BDNF and other risk factors for TD such as oxidative stress, antipsychotic treatment and genetic vulnerability deserve further investigation."
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By Mark Cowen