Gerald T. Voelbel

Caudate Nucleus Volume and Cognitive Performance: Are they related in Childhood Psychopathology?

BACKGROUND Impaired neuropsychological test performance, especially on tests of executive function and attention, is often seen in children diagnosed with autism spectrum disorders (ASD). Structures involved in fronto-striatal circuitry, such as the caudate nucleus, may support these cognitive abilities. However, few studies have examined caudate volumes specifically in children with ASD, or correlated caudate volumes to cognitive ability. METHODS Neuropsychological test scores and caudate volumes of children with ASD were compared to those of children with bipolar disorder (BD) and of typically developing (TD) children. The relationship between test performance and caudate volumes was analyzed. RESULTS The ASD group displayed larger right and left caudate volumes, and modest executive deficits, compared to TD controls. While caudate volume inversely predicted performance on the Wisconsin Card Sorting Test in all participants, it differentially predicted performance on measures of attention across the ASD, BD and TD groups. CONCLUSIONS Larger caudate volumes were related to impaired problem solving. On a test of attention, larger left caudate volumes predicted increased impulsivity and more omission errors in the ASD group as compared to the TD group, however smaller volume predicted poorer discriminant responding as compared to the BD group.

Short-term neuropsychological recovery in clients with substance use disorders

BACKGROUND Cognitive impairments are frequently observed in clients who enter treatment programs for substance abuse. The potential for early recovery of cognitive abilities is suggested by previous research; however, the extent of improvement and risk factors that may help predict individual differences in rates of recovery remain unclear. This study is a 6-week follow-up and retest of an original sample of 197 men and women who had received a broad neuropsychological assessment at addiction treatment entry. The aim was to examine the potential clinical significance of changes in cognitive functioning and the extent to which differential recovery was predictable from client background information. METHODS Fifteen neuropsychological tests were readministered to 169 of 197 clients 6 weeks after treatment entry. Structural equation modeling was used to estimate separately the practice effects and recovery in four cognitive domains: executive function, memory, information processing speed, and verbal ability. Client background information included age, sex, education, substance use and consequences, psychopathology, medical problems, familial alcoholism history, and childhood behavior problems. RESULTS A four-factor model of latent neuropsychological ability that was previously identified at treatment entry was replicated at follow-up. Statistically significant increases in the means of the four latent abilities were found. Memory showed a medium effect size improvement. Executive function, verbal ability, and information processing speed, however, showed only small effect size improvements, suggesting limited clinical significance. Substance use between treatment entry and follow-up, antisocial personality disorder, negative use consequences, less education, and medical problems were modestly predictive of less recovery. CONCLUSION Cognitive recovery in the first 6 weeks of treatment is possible, but, with the possible exception of memory, improvement may be minor in terms of clinical relevance.

Using co-variations in the Hb signal to detect visual activation: A near infrared spectroscopic imaging study

The premise of this report is that functional Near Infrared Spectroscopy (fNIRS) imaging data contain valuable physiological information that can be extracted by using analysis techniques that simultaneously consider the components of the measured hemodynamic response [i.e., levels of oxygenated, deoxygenated and total hemoglobin (oxyHb, deoxyHb and totalHb, respectively)]. We present an algorithm for examining the spatiotemporal co-variations among the Hb components, and apply it to the data obtained from a demonstrational study that employed a well-established visual stimulation paradigm: a contrast-reversing checkerboard. Our results indicate that the proposed method can identify regions of tissue that participate in the hemodynamic response to neuronal activation, but are distinct from the areas identified by conventional analyses of the oxyHb, deoxyHb and totalHb data. A discussion is provided that compares these findings to other recent studies using fNIRS techniques.

Individual differences in latent neuropsychological abilities at addictions treatment entry

The latent structure of neuropsychological abilities and risk factors for impairment were examined in 197 persons entering addictions treatment. Confirmatory factor analysis yielded 4 factors: Executive, Memory, Verbal, and Processing Speed. The measurement model was consistent with evidence that neuropsychological test performance is factorially complex and supported by multiple brain regions. Path analyses showed that risk factors explained 34%-57% of the true variance in abilities. Age, education, and medical status had the most generalized and robust associations with abilities. Drug use disorder diagnoses, childhood behavior problems, familial alcoholism, and psychopathology were also significantly related to specific latent abilities. Knowledge of neuropsychological impairment may be clinically useful, and selected risk factors may help treatment providers decide which clients should receive formal neuropsychological assessment.

Diffusion tensor imaging of traumatic brain injury review: Implications for neurorehabilitation

Diffusion tensor imaging (DTI) has widely been used to investigate the microstructural damage of white matter tracts that occur in individuals with traumatic brain injury (TBI). In the current review, we discuss the white matter regions which are commonly affected in adults with TBI. We also describe the current literature that has utilized DTI to investigate the relationship between microstructural integrity with neuropsychological performance and clinical outcome measures. Finally, a model is presented of the potential utilization of DTI as a biomarker of efficacy in neurorehabilitation for individuals with TBI.

Risk factors and neuropsychological recovery in clients with alcohol use disorders who were exposed to different treatments.

Risk covariates of neuropsychological ability (NA) at treatment entry and neuropsychological recovery (NR) across 15 months were examined and replicated in 2 samples (Ns = 952 and 774) from Project MATCH, a multisite study of alcoholism treatments. NA at treatment entry was associated with age, education, and other covariates. Statistically significant mean increases in NA over time had small effect sizes, suggesting limited clinical significance of NR in the samples as a whole. However, initial NA and a combination of risk factors in direct and mediated pathways predicted a large proportion of individual differences in NR. Statistically significant but modest differential treatment effects on NR suggest that addiction treatments may need to be modified or developed to facilitate this important aspect of recovery.

Cognition in multiple sclerosis: a review of neuropsychological and fMRI research.

Multiple Sclerosis (MS) is a disease of the central nervous system affecting millions of people worldwide. In addition to the disabling physical symptoms of MS, roughly 65% of individuals with MS also experience significant cognitive dysfunction, especially in the domains of learning/memory, processing speed (PS) and working memory (WM). The purpose of this review is to examine major topics in research on cognitive dysfunction, as well as review recent functional magnetic resonance imaging (fMRI) studies focusing on cognitive dysfunction in MS. Additionally, directions for future research are discussed.

The mean and the individual: integrating variable-centered and person-centered analyses of cognitive recovery in patients with substance use disorders.

Neuropsychological and cognitive deficits are observed in the majority of persons with alcohol and drug use disorders and may interfere with treatment processes and outcomes. Although, on average, the brain and cognition improve with abstinence or markedly reduced substance use, better understanding of the heterogeneity in the time-course and extent of cognitive recovery at the individual level is useful to promote bench-to-bedside translation and inform clinical decision making. This study integrated a variable-centered and a person-centered approach to characterize diversity in cognitive recovery in 197 patients in treatment for a substance use disorder. We assessed executive function, verbal ability, memory, and complex information processing speed at treatment entry, and then 6, 26, and 52 weeks later. Structural equation modeling was used to define underlying ability constructs and determine the mean level of cognitive changes in the sample while minimizing measurement error and practice effects on specific tests. Individual-level empirical growth plots of latent factor scores were used to explore prototypical trajectories of cognitive change. At the level of the mean, small to medium effect size gains in cognitive abilities were observed over 1 year. At the level of the individual, the mean trajectory of change was also the modal individual recovery trajectory shown by about half the sample. Other prototypical cognitive change trajectories observed in all four cognitive domains included Delayed Gain, Loss of Gain, and Continuous Gain. Together these trajectories encompassed between 86 and 94% of individual growth plots across the four latent abilities. Further research is needed to replicate and predict trajectory membership. Replication of the present findings would have useful implications for targeted treatment planning and the new cognitive interventions being developed to enhance treatment outcomes.

The Relationship between Neurocognitive Behavior of Executive Functions and the EFPT in Individuals with Multiple Sclerosis

The current study examined the relationship between two separate but complementary methods of assessing executive functions in individuals with multiple sclerosis (MS): (1) a neurocognitive approach with the Tower of London−DX (TOL-DX) test and (2) a functional top-down approach with the Executive Function Performance Test (EFPT). Sixty-eight individuals with MS (79% female) and 38 healthy controls (68% female) were administered both the TOL-DX test and the EFPT. For the group with MS, significant differences were found on the TOL-DX test and the EFPT executive components and functional tasks. For the group with MS, the number of moves to complete the TOL-DX tasks was significantly positively correlated to the Organization and Sequencing executive components of the EFPT and the Simple Cooking and Bill Payment tasks of the EFPT. The results demonstrate the relationship of executive function behavior and performance of instrumental activities of daily living tasks.

Neuroimaging and cognition using functional near infrared spectroscopy (fNIRS) in multiple sclerosis

The present study utilized functional near infrared spectroscopy (fNIRS) to detect neural activation differences in the orbitofrontal brain region between individuals with multiple sclerosis (MS) and healthy controls (HCs) during a working memory (WM) task. Thirteen individuals with MS and 12 HCs underwent fNIRS recording while performing the n-back WM task with four levels of difficulty (0-, 1-, 2-, and 3-back). Subjects were fitted with the fNIRS cap consisting of 30 ‘optodes’ positioned over the forehead. The results revealed different patterns of brain activation in MS and HCs. The MS group showed an increase in brain activation, as measured by the concentration of oxygenated hemoglobin (oxyHb), in the left superior frontal gyrus (LSFG) at lower task difficulty levels (i.e. 1-back), followed by a decrease at higher task difficulty (2- and 3-back) as compared with the HC group. HC group achieved higher accuracy than the MS group on the lower task loads (i.e. 0- and 1-back), however there were no performance differences between the groups at the higher task loads (i.e. 2- and 3-back). Taken together, the results suggest that individuals with MS experience a task with the lower cognitive load as more difficult than the HC group, and the brain activation patterns observed during the task confirm some of the previous findings from functional magnetic resonance imaging (fMRI) studies. This study is the first to investigate brain activation by utilizing the method of fNIRS in MS during the performance of a cognitive task.