Brain’s alpha activity is highly reduced in euthymic bipolar disorder patients

Abstract

Brain's alpha activity and alpha responses belong to major electrical signals that are related to sensory/cognitive signal processing. The present study aims to analyze the spontaneous alpha activity and visual evoked alpha response in drug free euthymic bipolar patients. Eighteen DSM-IV euthymic bipolar patients (bipolar I n = 15, bipolar II n = 3) and 18 healthy controls were enrolled in the study. Patients needed to be euthymic at least for 4 weeks and psychotrop free for at least 2 weeks. Spontaneous EEG (4 min eyes closed, 4 min eyes open) and evoked alpha response upon application of simple visual stimuli were analyzed. EEG was recorded at 30 positions. The digital FFT-based power spectrum analysis was performed for spontaneous eyes closed and eyes open conditions and the response power spectrum was also analyzed for simple visual stimuli. In the analysis of spontaneous EEG, the ANOVA on alpha responses revealed significant results for groups (F(1,34) = 8.703; P < 0.007). Post-hoc comparisons showed that spontaneous EEG alpha power of healthy subjects was significantly higher than the spontaneous EEG alpha power of euthymic patients. Furthermore, visual evoked alpha power of healthy subjects was significantly higher than visual evoked alpha power of euthymic patients (F(1,34) = 4.981; P < 0.04). Decreased alpha activity in spontaneous EEG is an important pathological EEG finding in euthymic bipolar patients. Together with an evident decrease in evoked alpha responses, the findings may lead to a new pathway in search of biological correlates of cognitive impairment in bipolar disorder.

Decrease of theta response in euthymic bipolar patients during an oddball paradigm

“…Several previous studies by our group reported that patients with bipolar disorder showed activation and synchronization deficits in different frequency ranges including delta, alpha, beta and gamma bands (Ö zerdem et al 2008, 2010, 2011Başar et al 2012). This is the first study in the theta frequency range.…”

“…Başar et al (2012) recently showed that, in spontaneous EEG, bipolar patients had significantly reduced alpha activity in comparison to healthy controls.…”

Topographic deficits in alpha-range resting EEG activity and steady state visual evoked responses in schizophrenia

“…1. Future studies would benefit from continuing to explore both alpha and other frequency bands to further delineate diagnosis-specific and more generalized neuropsychiatric EEG deficits (Schulman et al, 2011;Başar et al, 2012).…”

Resting state EEG power and coherence abnormalities in bipolar disorder and schizophrenia

“…With respect to spectral power, El Badri and colleagues found increased power at all frequencies (although markedly in the beta band) in BP relative to NC (El-Badri et al 2001), whereas Başar and colleagues reported reduced alpha power in euthymic patients (Başar et al 2012). Further, dysfunctional long-range connectivity appears to be more consistently observed in BP.…”