Habenular brain complex disrupted in affective disorders
MedWire News: Patients with unipolar or bipolar depression show significant reductions in habenular complex volume compared with mentally healthy controls, study findings show.
Contrary to their predictions, however, the researchers found that schizophrenia patients had a largely preserved habenular structure compared with controls.
“Because of its structural complexity and numerous connections with other brain areas, the habenular complex is implicated in many different neurotransmitter and modulator systems including dopamine, serotonin, acetylcholine, and gamma-aminobutyric acid (GABA),” write Hans-Gert Bernstein (University of Magdeburg, Germany) and colleagues in the journal Psychological Medicine.
Accumulating evidence suggests that this area plays a part in depression and deep brain stimulation targeting the habenular complex has shown antidepressive effects. Fewer studies have, however, addressed this area in schizophrenia.
To investigate the researchers studied archived brains sections of 14 patients with mood disorders (eight women) aged between 26 and 69 years (mean 48.6 years), of whom six had major depression and eight had bipolar disorder. Of the 14 patients, nine had died by suicide.
They also looked at the brains of 17 patients with schizophrenia (nine women) aged between 39 to 66 years (mean 52.6 years), and at control brains from five women and eight men aged between 38 and 66 years (mean 55.9 years).
Pathologic examination was performed using light microscopy and histology.
The researchers found that affective disorder patients showed a significant 20% reduction in medial and lateral habenula volume relative to mentally healthy controls and a significant 26.7% reduction in right side volume relative to schizophrenia patients. Schizophrenia patients did not differ significantly from controls.
Similarly there was a reduction in neuronal cell number and cell area in affective disorder patients for the right side compared to controls and schizophrenia patients. No such changes were seen in schizophrenia.
Bernstein et al comment: “The basic picture that emerges is that of a robust feedback control system regulating levels of dopamine and serotonin utilization.
“Further immunohistochemical investigations are necessary to relate different neurotransmitter to those alterations or search for targets in schizophrenia.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Andrew Czyzewski