Event-Related Potential N270 in Detecting Cognitive Impairment in Patients With Transient Ischemic Attack

Cognitive impairment in generalized anxiety disorder revealed by event-related potential N270

BACKGROUND

Cognitive function in anxiety disorders has been the subject of limited investigation, especially in generalized anxiety disorder (GAD). The purpose of this study was to investigate the cognitive function in subjects with GAD using mismatch-triggered negativity N270.

METHODS

Fifteen medication-free patients with a DSM-IV diagnosis of GAD, and 15 well-matched healthy controls performed a dual-feature delayed matching task while event-related potentials were recorded from their scalp.

RESULTS

The GAD group was characterized by the decreased N270 amplitude in the left hemisphere. The smaller N270 amplitude was associated with greater symptoms of anxiety and depression.

CONCLUSION

Since N270 is thought to index cognitive function in different domains, including attention and memory, our results suggest that individuals with GAD have an impaired cognitive function, particularly in selective attention and working memory. These cognitive deficits may have clinical significance in subjects with GAD and should be considered in treatment planning.

The altered cortical connectivity during spatial search for facial expressions in major depressive disorder

To characterize the altered directed connectivity within a distributed cortical network, as is associated with the impaired attention modulation involved in the manifestation of mood disorder in depression, short-window partial directed coherence (PDC) combining with the event-related brain potentials (ERPs) was applied in this study. ERPs were recorded from 13 normal subjects and 12 depressed patients during visual search for facial expressions. The evoked N2 component of ERPs by responding to all neutral faces (F(1,22)=5.51, P<0.05) and the positive face was reduced in the depressed patients as compared to the normal subjects (F(1,22)=5.71, P<0.05), while the evoked N2 component by detecting the negative face showed no significant between-group effect (F(1,22)=2.10, P=0.16). The reduced N2 amplitude reflected deficits in effortful attentional modulation in depression. Obtained PDC values within the N2 time-window (150-300 ms post stimulus) showed weaker intra-frontal and intra-central directed interactions and enhanced occipital information output when responding to all neutral faces in depression relative to those in the normal group. Few decreased intra-frontal directed interactions were observed when detecting the emotional face in depression. The altered cortical directed connectivity contributed to the impairment occurring in the effortful attention modulation in depression. Our findings supported that the impaired attention modulation processing in depression was associated with the altered cortical connectivity.

Attention changes in epilepsy patients following 3-month topiramate or valproate treatment revealed by event-related potential

The present study was designed to reveal changes of cognitive processes in epilepsy (EP) patients with Topiramate (TPM) or Valproate (VPA) treatment using Wechsler Adult Intelligence Scale (WAIS-CR) and event-related potential (ERP). Thirty untreated epilepsy patients were randomly divided into two groups receiving TPM or VPA, respectively. Fifteen healthy volunteers were included as controls. All the patients were examined by WAIS-CR and ERP before and 3 months after drug treatment. Controls were examined by ERP at the time recruited into the study and 3 months later. Unfamiliar grey-scale photographs of faces (front view) were used as stimuli. ERP were recorded at the same time. Mean Intelligence Quotient (IQ) in TPM group decreased after the 3-month treatment (90.40 vs. 81.00, P<0.05). One component of ERP-P300 was smaller in epilepsy patients than controls (P<0.05), but remained unchanged after TPM or VPA treatment (P>0.05). A delayed and smaller N270 was detected in patients compared to controls (P<0.05). After 3 months TPM treatment, it decreased further compared to before treatment (P<0.05). N170 was lower in patient groups, and it became lower after TPM treatment than before. Our results demonstrate that in all epilepsy patients with mild cognitive impairment ERP changes were found. TPM affected the cognitive functions in epilepsy patients reflected by the decreased full-scale intelligence quotient (FIQ). The imperative effects of TPM on visual perception function reflected by N170 were more obvious than that of VPA. Attention reflected by N270 was impaired after TPM treatment.