Resting-state network disruption and APOE genotype in Alzheimer's disease: a lagged functional connectivity study.

BACKGROUND: The apolipoprotein E epsilon 4 (APOE-4) is associated with a genetic vulnerability to Alzheimer's disease (AD) and with AD-related abnormalities in cortical rhythms. However, it is unclear whether APOE-4 is linked to a specific pattern of intrinsic functional disintegration of the brain after the development of the disease or during its different stages. This study aimed at identifying spatial patterns and effects of APOE genotype on resting-state oscillations and functional connectivity in patients with AD, using a physiological connectivity index called "lagged phase synchronization". METHODOLOGY/PRINCIPAL FINDINGS: Resting EEG was recorded during awake, eyes-closed state in 125 patients with AD and 60 elderly controls. Source current density and functional connectivity were determined using eLORETA. Patients with AD exhibited reduced parieto-occipital alpha oscillations compared with controls, and those carrying the APOE-4 allele had reduced alpha activity in the left inferior parietal and temporo-occipital cortex relative to noncarriers. There was a decreased alpha2 connectivity pattern in AD, involving the left temporal and bilateral parietal cortex. Several brain regions exhibited increased lagged phase synchronization in low frequencies, specifically in the theta band, across and within hemispheres, where temporal lobe connections were particularly compromised. Areas with abnormal theta connectivity correlated with cognitive scores. In patients with early AD, we found an APOE-4-related decrease in interhemispheric alpha connectivity in frontal and parieto-temporal regions. CONCLUSIONS/SIGNIFICANCE: In addition to regional cortical dysfunction, as indicated by abnormal alpha oscillations, there are patterns of functional network disruption affecting theta and alpha bands in AD that associate with the level of cognitive disturbance or with the APOE genotype. These functional patterns of nonlinear connectivity may potentially represent neurophysiological or phenotypic markers of AD, and aid in early detection of the disorder.

Positive effects of cerebrolysin on electroencephalogram slowing, cognition and clinical outcome in patients with postacute traumatic brain injury: an exploratory study.

The potential effects of Cerebrolysin (EBEWE Pharma, Unterach, Austria), a peptide preparation with neurotrophic activity, on brain bioelectrical activity, cognitive performance and clinical outcome in postacute traumatic brain injury (TBI) patients, were investigated in an exploratory study. A decrease in slow electroencephalogram (EEG) activity and an increase in fast frequencies were observed after the administration of Cerebrolysin. This EEG-activating effect was not influenced by TBI time course or severity, nor by the chronic treatment with nootropic compounds. Cognitive performance, evaluated with the Syndrome Kurztest test, improved in TBI patients after Cerebrolysin treatment, independent of disease severity, time course or disability. A significant improvement in the patients' clinical outcome, only evident during the first year after brain trauma, was also found following Cerebrolysin infusions. No relevant changes in biological parameters nor drug-related adverse events were observed. These promising preliminary results suggest that Cerebrolysin might be a useful treatment to improve the recovery of patients with traumatic brain damage, and encourage the conduction of confirmatory clinical trials.