Increased efficiency of brain connectivity networks in veterans with suicide attempts.

Background: Suicide is a public health concern for United States veterans and civilians. Prior research has shown neurobiological factors in suicide. However, studies of neuroimaging correlates of suicide risk have been limited. This study applied complex weighted network analyses to characterize the neural connectivity in white matter in veterans with suicide behavior. Methods: Twenty-eight veterans without suicide behavior (NS), 29 with a history of suicidal ideation only (SI), and 23 with prior suicide attempt (SA) completed diffusion tensor brain imaging, the Columbia Suicide Severity Rating Scale and Barratt Impulsiveness Scale (BIS). Structural connectivity networks among 82 parcellated brain regions were produced using whole-brain tractography. Global and nodal metrics of network topology have been calculated. Results: SA had shorter characteristic path length and greater global efficiency and mean weighted degree of global network metrics (p < 0.024). SA had more hub nodes than NS and SI. The left posterior cingulate cortex (PCC) showed significantly greater weighted degree in SA relative to others (p < 0.0003). Nonplanning subscale of BIS correlated with the weighted degrees of the left PCC within SA. In rich club connectivity, SA had higher local connections than others (p = 0.001). Conclusion: Veterans with prior suicide attempt had altered connectivity networks characteristics in the white matter. These findings may be distinctive neurobiological markers for individuals with suicide attempt. Strong connectivity in the left PCC may be implicated in impulsivity in veterans with suicide attempt.

Negative Mood States Correlate with Laterobasal Amygdala in Collegiate Football Players.

A number of studies have suggested that sports-related concussion (SRC) may place individuals at increased risk for depression and negative outcomes including suicide. However, the mechanisms underlying a potential relationship between brain integrity and mood remain unclear. The current study is aimed at examining the association between amygdala shape, mood state, and postconcussion symptoms in collegiate football players. Thirty members of 1 football team completed the Profile of Mood States (POMS), the postconcussion symptom scale (PCSS), and an MRI protocol during preseason camp. T1-weighted images were acquired and three-dimensional amygdala and probabilistic maps were created for shape analysis. Correlation analyses between POMS and PCSS and the relationship between POMS and amygdala shape were completed. In the amygdala, the left laterobasal subregion showed a positive relationship with the POMS total score and subscales scores. No significant relationship between PCSS and amygdala shape was found. Significant positive correlations were found between POMS subscales and PCSS. These results indicate that amygdala structure may be more closely associated with negative mood states than postconcussion symptoms. These findings suggest that premorbid individual differences in effect may provide critical insight into the relationship between negative mood and outcomes in collegiate football players with SRC.

Cortico-cerebellar abnormalities in adolescents with heavy marijuana use.

There are currently no studies that have evaluated the motor network, including the cerebellum, in adolescent marijuana (MJ) smokers. The current study aimed to evaluate whether there were activation differences in Brodmann's area 4 (BA4), Brodmann's area 6 (BA6), cingulate (CG) and cerebellum between MJ-using adolescents and healthy controls (HC) on a functional magnetic resonance imaging (fMRI) bilateral finger-tapping task. Twenty-four adolescents (aged 18.2 ± 0.7 years) with heavy MJ use and 24 HC (18.0 ± 1.9) had MRI scans on a 3T Siemens scanner, including a standard bilateral fMRI finger-tapping sequence. Imaging data were analyzed using SPM5 in Matlab. As regions of interest, BA4, BA6, cingulate (CG) and cerebellum were selected, and significant clusters of activity were thresholded at p<0.05, corrected. Healthy controls had significantly greater activation than MJ users for the CG and cerebellum. In addition, activation of the cerebellum and CG correlated with lifetime MJ smokes. This is one of the first studies to evaluate cortico-cerebellar circuits in adolescents with heavy MJ use. The study, which used a bilateral finger-tapping fMRI task, provides evidence for both CG and cerebellar dysfunction in MJ abuse and indicates that lifetime MJ use may impact the developing brain.