A paucity of a brain chemical known as brain-derived neurotrophic factor
may play a role in the development of tardive dyskinesia, a new study
The study was conducted by Yun Long Tan, M.D., a Ph.D. candidate at Peking
University in Beijing, China; Dong Feng Zhou, M.D., a professor of psychiatry
at Peking University and chair of the Chinese Psychiatric Association; and
Xiang Yang Zhang, M.D., Ph.D., associate research scientist at Yale
University. Results are in press with Schizophrenia Research.
Brain-derived neurotrophic factor is the most abundant nerve-nourishing
chemical in the brain. It is known to exert numerous effects on the central
nervous system, such as regulating neuronal growth, bolstering the action of
neurons that deploy various types of neurotransmitters, and assisting neurons
that have been stressed and injured. Various lines of research have also
suggested that the factor might be implicated in tardive dyskinesia. For
example, tardive dyskinesia is linked with neuronal degeneration, and the
factor can protect neurons from degeneration.
Tan and his coworkers set out to determine whether a deficiency of
brain-derived neurotrophic factor might be involved in tardive dyskinesia.
They selected as their subjects 80 schizophrenia patients with tardive
dyskinesia, 45 schizophrenia patients without the disorder, and 45 mentally
healthy individuals. All subjects lived in Beijing, and all three subject
groups were comparable in age and gender.
While brain-derived neurotrophic factor is highly concentrated in the
nervous system, it is also present in blood. Further, when the factor is
present in blood, it can cross the blood-brain barrier into the brain,
implying that levels of the factor in blood reflect levels in the brain. Thus,
Tan and his colleagues measured levels of brain-derived neurotrophic factor in
the blood of each of their subjects, then compared blood levels of the factor
among the three groups.
Blood levels of the factor were significantly lower in the schizophrenia
subjects with tardive dyskinesia than in schizophrenia subjects without it,
and also significantly lower in the former than in the healthy control group,
the researchers found. Moreover, subjects with more severe tardive dyskinesia
had even lower blood levels of the factor than did subjects with less severe
"Our results suggest that decreased brain-derived neurotrophic factor
may play an important role in the pathophysiology of tardive
dyskinesia," Tan and his group concluded.
One question raised by these results, Zhang told Psychiatric News,
is whether giving brain-derived neurotrophic factor to patients with tardive
dyskinesia might counter their tardive dyskinesia. He and his team will now
conduct a double-blind, randomized, placebo-controlled trial to determine
whether adding therapeutic amounts of brain-derived neurotrophic factor to
antipsychotic therapy might subdue tardive dyskinesia in schizophrenia
patients. To date, there is no standard treatment for the disorder.
The study was funded by the Chinese National Science Foundation, the
Capital Medical Development Scientific Foundation of Beijing, and the Beijing
Scientific and Technological New Stars Fund.
An abstract of "Decreased Plasma Brain-Derived Neurotrophic
Factor Levels in Schizophrenia Patients With Tardive Dyskinesia: Association
With Dyskinetic Movements" can be accessed online at<www.sciencedirect.com>
by clicking on "Browse A-Z of journals," "S," and"
Schizophrenia Research" and searching on title.▪