Quantitative Electroencephalography (QEEG) and Low-resolution Electromagnetic Tomography (LORETA) Analysis in Post Traumatic Stress Disorder (PTSD) Patients
Condition: Post-Traumatic Stress Disorder
MeSH terms: Stress Disorders, Traumatic; Stress Disorders, Post-Traumatic
Study type: Observational

Summary: 
      In this study the Quantitative Electroencephalography and low resolution topographic analysis
      of chronic Post-traumatic stress disorder and normal subjects will be compared.
    

Detailed description: 
      Post-traumatic stress disorder (PTSD) is defined as a constellation of symptoms in response
      to a stressor, including re-experiencing a traumatic event, numbed responsiveness and
      symptoms of an increased level of arousal (APA 2000) . In recent years there were many
      attempts to connect the brain structure and function to symptoms in PTSD patients (Francati,
      Vermetten et al. 2007; Liberzon and Sripada 2008). One of the important technologies in this
      regard is the Electroencephalography (EEG) measurement.

      The EEG is the reflection of the inner brain electrical changing dipole as it is measured on
      the scalp. It is measured by electrode that placed on the head according to the international
      distribution of electrodes called 10-20. The EEG recording that is the product of the
      measurement can be analyzed at least in three different levels: visual inspection of the raw
      EEG, quantities analysis of the EEG (QEEG) and based on the QEEG, calculating the electrical
      distribution of dipoles inside the brain that creates the EEG signal (Niedermeyer and Lopes
      da Silva 2005). Theoretically two EEG measurements could have the same visual EEG and/or QEEG
      patterns but the inner brain electrical dipole distribution could be very different. The
      mathematical solution to the calculation of the dipole distribution inside the brain, using
      the scalp EEG is based on "the inverse problem" concepts. One of the more common and precise
      method to solve the inverse problem regarding the EEG is called LORETA (low resolution
      topographic analysis) (Pascual-Marqui, Michel et al. 1994; Pascual-Marqui, Esslen et al.
      2002). There are many brain image technologies aiming on mapping the connection between brain
      function and psychopathology. Each method caries with it both advantage and drawbacks. The
      use of the Electroencephalographic mapping technique is no different and it's main advantage
      - the temporal resolution is with opposition to the relatively lower spatial resolution.
      Modern signal processing tools and software like the LORETA start challenging this equation
      and in the last years some articles were published proving the possibilities of using EEG
      measurement to localized brain function with high spatial-resolution (Stern, Neufeld et al.
      2009) .

      The study will focus on the rest QEEG and rest LORETA analysis in PTSD patients.

      Previous QEEG research found conflicting results regarding the spectral distribution of the
      EEG waves across the scalp.

      Begic et al (Begic, Hotujac et al. 2001) compared 18 PTSD veterans to 20 controls. They found
      that PTSD patients had increased theta activity over central regions, and they had increased
      beta activity over frontal, central and occipital regions. No significant differences were
      noted between the PTSD and control group in both the delta and alpha activity. In this study
      all the patients were medication free for 2 weeks.

      In another study the same group compared veterans with PTSD to veterans without PTSD. In this
      study the PTSD patients had decreased alpha power and increased beta power. No difference was
      noted on the theta band in this study (Jokic-Begic and Begic 2003).

      In a recent study another group studied the hemispheric asymmetries among motor vehicle
      survivors with PTSD, with subsyndromal PTSD, survivors without PTSD and nonexposed healthy
      controls during rest (baseline) and in response to neutral, positive, negative, and
      trauma-related pictures. They focus on the alpha band. They found no group differences in EEG
      alpha activity during the baseline condition. In there study all the patients were without
      medication for 1 month (Rabe, Beauducel et al. 2006). Shankman et al compared the resting EEG
      of PTSD patients to "super- controls" in order to maximized the difference between this two
      groups. They found no statistical significant difference in any of the spectral band
      (Shankman, Silverstein et al. 2008).

      The aim of this study is to calculate the QEEG difference and to do LORETA analysis in PTSD
      patients compared to controls.

      In order to avoid statistical multiple compressing problems this study will focus on the
      theta band. There are at least two reasons for this: the first is that due to ethical issue
      we don't ask our patients to stop there psychotropic treatments therefore all of them are
      using SSRI antidepressants which could cause some alpha rhythms changes (Niedermeyer and
      Lopes da Silva 2005). Another reason is that the origin of the theta bend is supposed to be
      the in limbic system (Niedermeyer and Lopes da Silva 2005) that is long ago connected to PTSD
      symptoms (Francati, Vermetten et al. 2007).
    

Observational model: Case-Control
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Veterans with chronic PTSD of at least 2 years.
      
Keywords: PTSD; EEG; QEEG; LORETA