New and Noteworthy Information—June 2013
The infralimbic and prelimbic prefrontal cortices may undergo functional changes to compensate for damage to the hippocampus, according to a study published online ahead of print May 15 in Proceedings of the National Academy of Sciences. Disconnection of these cortices in animals with compromised dorsal hippocampi and immediate early gene induction profiles for amygdala-projecting prefrontal cells suggested that communication and dynamic rebalancing within this prefrontal microcircuit is crucial. The infralimbic cortex normally helps to limit the generalization of contextual fear. The study results indicate that plasticity through the recruitment of alternate circuits allows the brain to compensate following damage and may result in targeted treatment of memory disorders, according to the researchers.
Among patients with psychogenic nonepileptic seizures (PNES), traumatic brain injury (TBI) may be associated with increased psychiatric comorbidities, symptom severity, poorer functioning, and increased disability, according to research published in the April issue of Epilepsia. Investigators reviewed medical records for 92 patients with EEG-confirmed PNES to assess variables including demographics, head injury, and neurologic status. Of the study population, 41 patients (44.6%) had a history of TBI, and 30 of these subjects (73%) had mild TBI. Patients with TBI had more mood disorder diagnoses, were more likely to receive disability, and had lower global functioning than patients with PNES without TBI, after adjusting for age and sex. Patients with TBI and PNES had significantly increased odds for having major depression, behavioral impulsivity, and post-traumatic stress disorder.
In patients with restless legs syndrome (RLS), glutamate may have a strong relation with arousal sleep disturbance, but not with the motor features of RLS, according to research published online ahead of print April 26 in Neurology. Investigators performed hydrogen magnetic resonance spectroscopy of the right thalamus on 28 subjects with RLS and 20 matched controls. They assessed the Glx signal (a combination of glutamate and glutamine) as a ratio to the total creatine. The Glx/Cr ratio was higher for patients with RLS than for controls and correlated significantly with wake time during the sleep period and all other RLS-related polysomnographic sleep variables except periodic leg movements during sleep (PLMS) per hour. In contrast, dopamine has a limited relation to arousal sleep disturbance and a strong relation to PLMS.
Total brain volume, gray matter volume, and white matter volume may be smaller among patients with migraine and depression than among subjects with one or neither of these conditions, according to research published online ahead of print May 22 in Neurology. Investigators assessed 4,296 participants from the population-based Age, Gene/Environment Susceptibility–Reykjavik Study for migraine between 1967 and 1991. From 2002 to 2006, clinicians diagnosed lifetime history of major depressive disorder according to DSM-IV criteria and acquired MRIs of participants’ brains. Migraineurs with depression may represent a distinct clinical phenotype with different long-term sequelae, according to the investigators. The group pointed out that the number of subjects in their study was relatively small and that their findings needed to be confirmed in future studies.
Suicide risk may be higher among military personnel with more lifetime traumatic brain injuries (TBIs), even after controlling for clinical symptom severity, according to research published online ahead of print May 15 in JAMA Psychiatry. Investigators examined 161 military personnel with suspected head injury who completed standardized self-report measures of depression, posttraumatic stress disorder (PTSD), and suicidal thoughts and behaviors. Depression, PTSD, and TBI symptom severity significantly increased with the number of TBIs. An increased incidence of lifetime suicidal thoughts or behaviors was associated with the number of TBIs, as was suicidal ideation within the past year. The number of TBIs was associated with greater suicide risk when controlling for the effects of depression, PTSD, and TBI symptom severity. A significant interaction between depression and cumulative TBIs also was found.
Focal ischemic stroke may cause pathologic disturbances in ipsilateral and contralateral brain areas, according to a study published on May 10 in PLOS One. These disturbances may be closely associated with the breakdown of the blood–brain barrier (BBB) and the accumulation of endothelial autophagosomes. Investigators randomly assigned 28 adult male rats to a control group or to occlusion of the middle cerebral artery through the intraluminal filament technique. After 60 minutes of occlusion, rats in the intervention group were reperfused. Seven days after occlusion, investigators found significant BBB alterations in the ipsilateral hemispheres of the intervention rats. The microvascular damage observed in occluded rats during the subacute phase likely revealed ischemic diaschisis and should be considered in the development of treatment strategies for stroke, said the researchers.
—Erik Greb
Senior Associate Editor
