Effects of attentional bias modification therapy on the cue reactivity and cognitive control networks in participants with cocaine use disorders.

BACKGROUND: While attentional bias modification therapy (ABMT) alters drug-related behaviors in some substance users, results have been mixed in individuals with cocaine use disorders (CUD). OBJECTIVES: The current study examined whether ABMT affected brain functioning during independent measures of cue reactivity (i.e., cocaine versus food cues) and cognitive control (i.e., incongruent versus congruent trials), and whether brain activity was associated with baseline or post-intervention cocaine use. METHODS: 37 participants (62% male) were randomly assigned to ABMT or control therapy. Clinical and neuroimaging assessments occurred at baseline and immediately post-intervention, with additional clinical testing at 2 weeks and 3 months following intervention. Cocaine use was assessed through self-report. RESULTS: Slower reaction times and increased functional activation (prefrontal cortex, posterior parietal cortex) were observed for incongruent versus congruent stimuli and increased functional activation for cocaine relative to food videos (ventral striatum, dorsolateral prefrontal cortex and orbitofrontal cortex). The default-mode network (DMN) was not deactivated during exposure to cocaine videos. The degree of activation during cocaine relative to food cues was associated with baseline cocaine use (insula only) and reduction in use following treatment (insula and anterior DMN) above and beyond clinical variables. Cognitive control network activity was not associated with cocaine use at baseline or following treatment. ABMT therapy did not differentially affect cocaine use or functional activation during either task. CONCLUSION: Current results suggest a relationship between cue reactivity network activation and cocaine use, but question the efficacy of ABMT in changing brain function during cue reactivity or cognitive control tasks.

A Randomized Trial of Combined tDCS Over Right Inferior Frontal Cortex and Cognitive Bias Modification: Null Effects on Drinking and Alcohol Approach Bias.

BACKGROUND: Deriving novel treatments for alcohol use disorders (AUDs) is of critical importance, as existing treatments are only modestly effective for reducing drinking. Two promising strategies for treating AUDs include cognitive bias modification (CBM) and transcranial direct current stimulation (tDCS). While each strategy has shown positive results in reducing drinking or alcohol-related constructs (e.g., craving), initial tests of the combination of CBM and tDCS have shown mixed results. The present study investigated the degree to which combining CBM and tDCS (2.0 mA anodal current over F10) could reduce alcohol approach biases and alcohol consumption. METHODS: Seventy-nine at-risk drinkers were randomized to 1 of 4 conditions in a 2 × 2 factorial design: verum CBM/verum tDCS, verum CBM/sham tDCS, sham CBM/verum tDCS, or sham CBM/sham tDCS. Participants completed a baseline assessment of alcohol approach bias and drinking quantity/frequency (i.e., drinks per drinking day [DDD] and percent heavy drinking days [PHDD]), 4 sessions of combined CBM and tDCS, and follow-up assessments of approach bias and alcohol consumption. RESULTS: Results indicated that while participants did demonstrate significant alcohol approach biases at baseline, neither CBM, tDCS, nor the interaction reduced the bias at the follow-up. In addition, there was evidence of a trend toward reducing DDD from baseline to the 1-week/1-month follow-ups, but there was no significant effect of the intervention on either DDD or PHDD. CONCLUSIONS: These results partially replicated null results presented in similar CBM/tDCS trials and suggest that this combination, at least with anodal stimulation over dorsolateral or inferior frontal sites, may have limited utility to reduce drinking.

The efficacy of attention bias modification therapy in cocaine use disorders.

BACKGROUND: Attentional bias (i.e., differences in reaction time between drug and neutral cues) has been associated with a variety of drug-use behaviors (e.g., craving, abstinence). Reduction of bias may ultimately reduce use. OBJECTIVE: The current study examined whether attentional bias modification therapy (ABMT) reduced the frequency of drug use behaviors in individuals with cocaine use disorder (CUD). METHOD: Participants (n = 37) were randomly assigned to ABMT or control therapy, which systematically varied how frequently probes replaced neutral (ABMT = 100%; control therapy = 50%) relative to drug stimuli. Each intervention included 5 training sessions comprising a total of 2640 trials over 4 weeks. Clinical assessments occurred at baseline, post-intervention, 2 weeks and 3 months posttreatment. RESULTS: There were no baseline differences between groups on drug-use behaviors or other clinical measures. Contrary to predictions, both groups exhibited slower rather than faster reaction times for cocaine stimuli (p = 0.005) at baseline, with no relationship between bias and baseline measures of drug-use behavior. CONCLUSIONS: ABMT was not more effective than our control therapy at reducing attentional bias, reducing craving or changing other drug use behaviors. Current results suggest additional replication studies are needed to assess ABMT's efficacy in reducing drug-use behaviors in CUD.

A functional magnetic resonance imaging study of cognitive control and neurosensory deficits in mild traumatic brain injury.

Mild traumatic brain injury patients (mTBI) frequently report symptoms of increased distractability and sensory disturbances during mutisensory stimulation. These common post-concussive symptoms could putatively result from dysfunction within the cognitive control network (CCN; top-down) or from unisensory cortex (bottom-up) itself. Functional magnetic resonance imaging (fMRI) and high-resolution structural data were therefore prospectively collected during a multisensory (audio-visual) cognitive control task from 46 mTBI patients within 3 weeks of injury and 46 matched healthy controls (HC), with a subset of participants returning at 4 months. Multisensory stimuli were presented at two frequencies to manipulate cognitive and perceptual load. Patients self-reported more cognitive, emotional, somatic, vestibular and visual symptoms relative to HC, which improved, but did not entirely resolve, over the 4 month follow-up period. There were no group differences in behavior or functional activation during cognitive control (incongruent--congruent trials). In contrast, patients exhibited abnormal activation within different regions of visual cortex that depended on whether attention was focused on auditory or visual information streams. Patients also exhibited increased activation within bilateral inferior parietal lobules during higher cognitive/perceptual loads, suggesting a compensatory mechanism to achieve similar levels of behavioral performance. Functional abnormalities within the visual cortex and inferior parietal lobules were only partially resolved at 4 months post-injury, suggesting that neural abnormalities may take longer to resolve than behavioral measures used in most clinical settings. In summary, current results indicate that abnormalities within unisensory cortex (particularly visual areas) following mTBI, which likely contribute to deficits commonly reported during multisensory stimulation.

An fMRI study of multimodal selective attention in schizophrenia.

BACKGROUND: Studies have produced conflicting evidence regarding whether cognitive control deficits in patients with schizophrenia result from dysfunction within the cognitive control network (CCN; top-down) and/or unisensory cortex (bottom-up). AIMS: To investigate CCN and sensory cortex involvement during multisensory cognitive control in patients with schizophrenia. METHOD: Patients with schizophrenia and healthy controls underwent functional magnetic resonance imaging while performing a multisensory Stroop task involving auditory and visual distracters. RESULTS: Patients with schizophrenia exhibited an overall pattern of response slowing, and these behavioural deficits were associated with a pattern of patient hyperactivation within auditory, sensorimotor and posterior parietal cortex. In contrast, there were no group differences in functional activation within prefrontal nodes of the CCN, with small effect sizes observed (incongruent-congruent trials). Patients with schizophrenia also failed to upregulate auditory cortex with concomitant increased attentional demands. CONCLUSIONS: Results suggest a prominent role for dysfunction within auditory, sensorimotor and parietal areas relative to prefrontal CCN nodes during multisensory cognitive control.

A prospective microstructure imaging study in mixed-martial artists using geometric measures and diffusion tensor imaging: methods and findings.

Although diffusion magnetic resonance imaging (dMRI) has been widely used to characterize the effects of repetitive mild traumatic brain injury (rmTBI), to date no studies have investigated how novel geometric models of microstructure relate to more typical diffusion tensor imaging (DTI) sequences. Moreover, few studies have evaluated the sensitivity of different registration pipelines (non-linear, linear and tract-based spatial statistics) for detecting dMRI abnormalities in clinical populations. Results from single-subject analyses in healthy controls (HC) indicated a strong negative relationship between fractional anisotropy (FA) and orientation dispersion index (ODI) in both white and gray matter. Equally important, only moderate relationships existed between all other estimates of free/intracellular water volume fractions and more traditional DTI metrics (FA, mean, axial and radial diffusivity). These findings suggest that geometric measures provide differential information about the cellular microstructure relative to traditional DTI measures. Results also suggest greater sensitivity for non-linear registration pipelines that maximize the anatomical information available in T1-weighted images. Clinically, rmTBI resulted in a pattern of decreased FA and increased ODI, largely overlapping in space, in conjunction with increased intracellular and free water fractions, highlighting the potential role of edema following repeated head trauma. In summary, current results suggest that geometric models of diffusion can provide relatively unique information regarding potential mechanisms of pathology that contribute to long-term neurological damage.

Static and Dynamic Intrinsic Connectivity following Mild Traumatic Brain Injury.

Mild traumatic brain injury (mTBI) is the most common neurological disorder and is typically characterized by temporally limited cognitive impairment and emotional symptoms. Previous examinations of intrinsic resting state networks in mTBI have primarily focused on abnormalities in static functional connectivity, and deficits in dynamic functional connectivity have yet to be explored in this population. Resting-state data was collected on 48 semi-acute (mean = 14 days post-injury) mTBI patients and 48 matched healthy controls. A high-dimensional independent component analysis (N = 100) was utilized to parcellate intrinsic connectivity networks (ICN), with a priori hypotheses focusing on the default-mode network (DMN) and sub-cortical structures. Dynamic connectivity was characterized using a sliding window approach over 126 temporal epochs, with standard deviation serving as the primary outcome measure. Finally, distribution-corrected z-scores (DisCo-Z) were calculated to investigate changes in connectivity in a spatially invariant manner on a per-subject basis. Following appropriate correction for multiple comparisons, no significant group differences were evident on measures of static or dynamic connectivity within a priori ICN. Reduced (HC > mTBI patients) static connectivity was observed in the DMN at uncorrected (p < 0.005) thresholds. Finally, a trend (p = 0.07) for decreased dynamic connectivity in patients across all ICN was observed during spatially invariant analyses (DisCo-Z). In the semi-acute phase of recovery, mTBI was not reliably associated with abnormalities in static or dynamic functional connectivity within the DMN or sub-cortical structures.

A Longitudinal Assessment of Structural and Chemical Alterations in Mixed Martial Arts Fighters.

Growing evidence suggests that temporally proximal acute concussions and repetitive subconcussive head injuries may lead to long-term neurological deficits. However, the underlying mechanisms of injury and their relative time-scales are not well documented in human injury models. The current study therefore investigated whether biomarkers of brain chemistry (magnetic resonance [MR] spectroscopy: N-acetylaspartate [NAA], combined glutamate and glutamine [Glx], total creatine [Cre], choline compounds [Cho], and myo-inositol [mI]) and structure (cortical thickness, white matter [WM]/subcortical volume) differed between mixed martial artists (MMA; n = 13) and matched healthy controls (HC) without a history of contact sport participation (HC; n = 14). A subset of participants (MMA = 9; HC = 10) returned for follow-up visits, with MMA (n = 3) with clinician-documented acute concussions also scanned serially. As expected, MMA self-reported a higher incidence of previous concussions and significantly more cognitive symptoms during prior concussion recovery. Fighters also exhibited reduced memory and processing speed relative to controls on neuropsychological testing coupled with cortical thinning in the left posterior cingulate gyrus and right occipital cortex at baseline assessment. Over a 1-year follow-up period, MMA experienced a significant decrease in both WM volume and NAA concentration, as well as relative thinning in the left middle and superior frontal gyri. These longitudinal changes did not correlate with self-reported metrics of injury (i.e., fight diary). In contrast, HC did not exhibit significant longitudinal changes over a 4-month follow-up period (p > 0.05). Collectively, current results provide preliminary evidence of progressive changes in brain chemistry and structure over a relatively short time period in individuals with high exposure to repetitive head hits. These findings require replication in independent samples.

Frontotemporal anatomical connectivity and working-relational memory performance predict everyday functioning in schizophrenia.

Hippocampal (relational memory) and prefrontal cortex (PFC; working memory) impairments have been found in patients with schizophrenia (SP), possibly due to a dysfunctional connection between structures. Neuroanatomical studies that describe reduced fractional anisotropy (FA) in the uncinate fasciculus support this idea. The dysconnection hypothesis in SP was investigated by examining frontotemporal anatomical connectivity (uncinate fasciculus FA) and PFC-hippocampal memory and their relationship with each other and everyday functioning. PFC-hippocampal memory was examined with two working-relational memory tasks: transverse patterning and a virtual Morris water task. SP exhibited a performance deficit on both tasks and had lower FA in bilateral uncinate fasciculus than healthy volunteers. Lower frontotemporal anatomical connectivity was related to lower working-relational memory performance, and both predicted worse everyday functioning.