Decreased interhemispheric connectivity and increased cortical excitability in unmedicated schizophrenia: A prefrontal interleaved TMS fMRI study

BACKGROUND

Prefrontal abnormalities in schizophrenia have consistently emerged from resting state and cognitive neuroimaging studies. However, these correlative findings require causal verification via combined imaging/stimulation approaches. To date, no interleaved transcranial magnetic stimulation and functional magnetic resonance imaging study (TMS fMRI) has probed putative prefrontal cortex abnormalities in schizophrenia.

OBJECTIVE

/Hypothesis: We hypothesized that subjects with schizophrenia would show significant hyperexcitability at the site of stimulation (BA9) and decreased interhemispheric functional connectivity.

METHODS

We enrolled 19 unmedicated subjects with schizophrenia and 22 controls. All subjects underwent brain imaging using a 3T MRI scanner with a SENSE coil. They also underwent a single TMS fMRI session involving motor threshold (rMT) determination, structural imaging, and a parametric TMS fMRI protocol with 10 Hz triplet pulses at 0, 80, 100 and 120% rMT. Scanning involved a surface MR coil optimized for bilateral prefrontal cortex image acquisition.

RESULTS

Of the original 41 enrolled subjects, 8 subjects with schizophrenia and 11 controls met full criteria for final data analyses. At equal TMS intensity, subjects with schizophrenia showed hyperexcitability in left BA9 (p = 0.0157; max z-score = 4.7) and neighboring BA46 (p = 0.019; max z-score = 4.47). Controls showed more contralateral functional connectivity between left BA9 and right BA9 through increased activation in right BA9 (p = 0.02; max z-score = 3.4). GM density in subjects with schizophrenia positively correlated with normalized prefrontal to motor cortex ratio of the corresponding distance from skull to cortex ratio (S-BA9/S-MC) (r = 0.83, p = 0.004).

CONCLUSIONS

Subjects with schizophrenia showed hyperexcitability in left BA9 and impaired interhemispheric functional connectivity compared to controls. Interleaved TMS fMRI is a promising tool to investigate prefrontal dysfunction in schizophrenia.

Correction to: PTSD and gender: could gender differences in war trauma types, symptom clusters and risk factors predict gender differences in PTSD prevalence?

AbstractThe female-male ratio in the prevalence of post-traumatic stress disorder (PTSD) is approximately 2:1. Gender differences in experienced trauma types, PTSD symptom clusters, and PTSD risk factors are unclear. We aimed to address this gap using a cross-sectional design. A sample of 991 civilians (522 women, 469 men) from South Lebanon was randomly selected in 2007, after the 2006 war. Trauma types were grouped into disaster and accident, loss, chronic disease, non-malignant disease, and violence. PTSD symptom clusters involved re-experiencing, avoidance, negative cognitions and mood, and arousal. These were assessed using parts I and IVof the Arabic version of the Harvard Trauma Questionnaire (HTQ). Risk factors were assessed using data from a social support and life events questionnaire in multiple regression models. Females were twice as likely as males to score above PTSD threshold (24.3 vs. 10.4%, p ˂ 0.001). Total scores on all trauma types were similar across genders. Females scored higher on all symptom clusters (p < 0.001). Social support, social life events, witnessed traumas, and domestic violence significantly were associated with PTSD in both genders. Social support, social life events, witnessed traumas and domestic violence were significantly associated with PTSD in both genders. Conversely, gender difference in experienced traumas was not statistically significant. These findings accentuate the need to re-consider the role of gender in the assessment and treatment of PTSD.

Focus Groups Investigating Mental Health Attitudes and Beliefs of Parents and Teachers in South Lebanon: Are They Culturally Determined?

Introduction: The wars that Lebanon had endured led to a devastating number of deaths, injuries, and displacements. Such tragedies have detrimentally affected its civilians psychologically. Purpose: To identify knowledge, attitudes, and practices of teachers and parents concerning child/adolescent mental health. Method: Using purposeful sampling, five focus groups were conducted with teachers and parents of students from elementary, middle, and secondary levels in two private hub schools in South Lebanon. Results: A total of 27 teachers and 18 parents participated separately in focus groups. Three themes emerged: (a) Mental health care is a priority for overall health, (b) Mental illness is a cultural taboo, and (c) There is a need for better education and cultural understanding about mental health. Discussion: This is the first study in Lebanon directly targeted at parents’ and teachers’ mental health concerns. Such findings will add to transcultural nursing knowledge about the importance of mental health care.

PTSD and depression construct: prevalence and predictors of co-occurrence in a South Lebanese civilian sample

BACKGROUND

Armed conflict, occupation, and political and economic instability that are particularly experienced by the civilian Lebanese population of South Lebanon would almost inevitably affect these individuals psychologically. Therefore, identifying predictors of co-occurring mental disorders is paramount to sound assessment and intervention planning.

OBJECTIVE

This study aims to determine the prevalence and predictors of co-occurring posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) in a post-war population from South Lebanon.

METHOD

A total of 991 citizens from 10 villages were interviewed using a cross-sectional design through random sampling. The prevalence of PTSD, MDD, or both was 23.4%. To identify predictors of PTSD and depression co-occurrence, multinomial logistic regression was used. Participants were divided into four groups (participants with no PTSD or depression, participants with PTSD only, participants with depression only, and participants with PTSD-depression comorbidity).

RESULTS

Among the significant predictors of PTSD-depression co-occurrence, female gender, health problems, social life events, and witnessed traumatic events were most consistently found. Additionally, employment and educational status, as well as social support, were found to significantly predict co-occurrence.

CONCLUSIONS

Results reveal the distinct risk and protective factors that characterize the PTSD-depression profile. These findings will hopefully assist in the development of interventions that are sensitive to individuals' psychosocial milieu.