Biomedical subjects

Robert M Roth

Publications and source records attributed to Robert M Roth.

15 recordsLinked to original sources

PubMed2006

Self- and informant reports of executive function on the BRIEF-A in MCI and older adults with cognitive complaints.

Amnestic mild cognitive impairment (MCI) is characterized by impaired episodic memory, although subtle executive problems have been noted on neuropsychological tests. Recent research also has described a group of healthy, non-depressed older adults with significant cognitive complaints (CC) but normal performance on neuropsychological testing. These individuals show structural and functional brain changes intermediate between those seen in MCI and healthy older adults without such complaints (HC). We evaluated executive functions in MCI and CC using the Behavior Rating Inventory of Executive Function-Adult version (BRIEF-A), a newly developed self- and informant report questionnaire in 29 patients with amnestic MCI, 28 CCs, and 30 demographically matched HCs. MCI and CC participants reported significant difficulties with selective aspects of executive functioning relative to HCs despite clinically normal performance on neuropsychological tests of this cognitive domain. Scores were generally in the pattern of MCI>CC>HC, and findings were most pronounced for working memory. Additionally, MCI and CC participants were more likely than their informants to report clinically meaningful executive problems, though informants identified a similar pattern of difficulty overall. Results failed to reveal strong relations between the BRIEF-A and standardized neuropsychological tests of executive function. Overall findings indicate that the BRIEF-A is sensitive to subtle executive changes in MCI and CC and suggest the need for research to determine if executive complaints are predictive of clinical course.

Aged↗

PubMed2006

The fornix and mammillary bodies in older adults with Alzheimer's disease, mild cognitive impairment, and cognitive complaints: a volumetric MRI study.

The fornix and mammillary bodies are important limbic structures that have not been systematically investigated in the earliest stages of preclinical dementia. The present study examined volumetric changes in the fornix and mammillary bodies and improved previously established tracing guidelines to increase reliability and provide more comprehensive measurements. Volumetric measurements were made in euthymic older adults, including 16 patients with mild Alzheimer's disease (AD), 20 patients with amnestic mild cognitive impairment (MCI), 20 individuals with cognitive complaints (CC) but normal neuropsychological test performance, and 20 demographically matched healthy controls (HC). Structural magnetic resonance imaging included a T1-weighted 1.5-mm coronal volume, acquired on a GE 1.5T LX scanner. After adjustment for total intracranial volume (ICV), significant volume reductions were observed in the fornix and mammillary bodies in patients with AD as compared with HC, CC, and MCI participants. No volume differences were seen between the HC, CC, and MCI groups. Study findings are consistent with previous research showing volume decreases of the fornix and mammillary bodies in AD, and provide new data on the relative preservation of these structures in preclinical disease stages. Results suggest that atrophy of the fornix and mammillary bodies becomes apparent at the point of conversion from MCI to AD. Longitudinal assessments are needed to delineate the time course and extent of the observed volumetric changes.

Aged↗

PubMed2006

Functional magnetic resonance imaging of executive control in bipolar disorder.

Bipolar disorder has been associated with dysfunction of executive control processes. Using functional magnetic resonance imaging, we examined brain activation during a counting Stroop task in 11 healthy adults and 11 patients with bipolar I disorder. Results revealed greater activation for the healthy than bipolar disorder group in distributed brain regions that included the right inferior and medial frontal gyri. With the exception of one area within the left posterior cingulate gyrus that was correlated with mania severity, regional activations where group differences were observed were not associated with mood symptoms in the patient group. These findings add to the growing body of evidence implicating neural circuitry subserving executive control in bipolar disorder.

Adult↗

PubMed2006

The influence of difficult temperament on alcohol-related aggression: better accounted for by executive functioning?

The purpose of this investigation was to test the hypothesis that executive functioning (EF) would mediate the relation between difficult temperament (DT) and intoxicated aggression. Participants were 165 social drinking men and women between the ages of 21-35years old. DT was measured using the Dimension of Temperament Scale - Revised and EF was measured using seven well-established neuropsychological tests. Following consumption of an alcoholic beverage, participants were tested on a laboratory aggression measure in which electric shocks were received from and administered to a fictitious opponent under the guise of a competitive reaction time task. Aggression was operationalized as shock intensities administered to the fictitious opponent under conditions of low and high provocation. Results indicated that EF successfully mediated the relation between DT and intoxicated aggression for men but not for women. These findings are discussed with regard to how they influence current models of aggressive behavior as well as their implications for future violence prevention efforts.

Adult↗

PubMed2005

Treatment of substance use disorders in schizophrenia: a unifying neurobiological mechanism?

Substance use disorders (SUDs) are highly prevalent and are associated with poor outcomes among individuals with schizophrenia. Integrating treatments for both disorders improves outcomes. Numerous individual pharmacologic and psychosocial treatments have shown effectiveness at reducing substance use in individuals with a primary diagnosis of schizophrenia and co-occurring substance use disorders. Of these treatments, medications such as certain atypical antipsychotics and naltrexone, and psychosocial treatments such as contingency management, seem to be particularly promising. The development and evaluation of psychopharmacologic and psychosocial treatments for SUDs in schizophrenia would benefit from a better understanding of the neurobiological mechanisms underlying the effectiveness of such treatments. Several theories have been put forth to explain the heightened risk for SUDs in schizophrenia. Of these, brain reward circuitry dysfunction, hypothesized to be etiologically important in SUDs, may be an especially salient target for treatments aimed at the reduction of substance use in patients with schizophrenia. We review current pharmacologic and psychosocial treatments for SUDs in schizophrenia, and theoretical mechanisms underlying the increased risk for SUDs in this population. We propose that effective treatments may in part work through the modulation of brain reward circuitry dysfunction.

Brain↗

PubMed2005

Neuropsychological functioning in early- and late-onset obsessive-compulsive disorder.

Significant relationships have been noted between age of onset and demographics, clinical characteristics, and cerebral metabolic activity in obsessive-compulsive disorder (OCD). The authors investigated whether patients with early (N=21) and late (N=17) onset OCD differ with respect to neuropsychological functioning. Results revealed that the late onset OCD group obtained poorer scores on measures of executive function and auditory attention than the early onset group. Late onset OCD was also associated with poorer visual memory relative to healthy comparison subjects. These findings suggest that early and late onset OCD may be the result of at least partially differing neurobiological mechanisms.

Adolescent↗

PubMed2004

Organizational strategy use in obsessive-compulsive disorder.

Patients with obsessive-compulsive disorder (OCD) have been demonstrated to be less likely to use spontaneously generated organizational strategies during verbal episodic memory and visuoconstruction tasks. However, whether this organizational deficit is generalizable to other areas of cognitive functioning has not been established. In the present study, we assessed whether adults with OCD are less likely to spontaneously generate organizational strategies during performance of an executive function test, the Self-Ordered Pointing Task (SOPT). Participants included 30 adults with OCD and 24 healthy controls. Groups did not differ with respect to the time to complete or number of errors made on the SOPT. Furthermore, group differences were not observed in the ability to generate organizational strategies or in the specific types of strategies employed to complete the SOPT. These findings indicate that a reduced use of organizational strategies in OCD is not present across all cognitive domains.

Adult↗

PubMed2004

The neural circuitry of reward and its relevance to psychiatric disorders.

Scientific interest in how the brain processes reward has burgeoned during the past 50 years since the discovery that rats will do tasks such as pressing a lever to obtain electrical stimulation of the brain. This interest was additionally encouraged by the observation of an association between reward and dopamine activity in the mesocorticolimbic system. In this article, we will discuss the complex nature of reward processing and recent animal studies and human functional neuroimaging studies to elucidate the current understanding of the neural substrates of reward processing and its components. Lastly, we will review recent theoretical and empirical work investigating the role of brain reward circuitry in several psychiatric disorders, including substance use disorders, schizophrenia, pathologic gambling, major depressive disorder, and attention-deficit/hyperactivity disorder.

Animals↗

PubMed2004

ERP study of pre-attentive auditory processing in treatment-refractory schizophrenia.

Event-related potential (ERP) studies have demonstrated impaired auditory sensory processing in patients with schizophrenia, as reflected in abnormal mismatch negativity (MMN). We sought to extend this finding by evaluating MMN in 13 treatment-refractory patients with schizophrenia, and 14 age- and gender-matched healthy controls. Subjects responded to infrequent visual stimulation while ignoring binaurally presented auditory tones. The amplitude and topographical pattern of the MMN were analyzed. The control group presented the expected reduction in the amplitude of the MMN from frontal to central and parietal locations. In comparison, the MMN amplitude was not reduced in the treatment-refractory patients, and was largest at the central-posterior electrode location. In addition, patients displayed larger negativities at left frontal, and left- and right-temporal electrode locations than the control subjects. These findings are consistent with pre-attentive abnormalities in treatment-refractory patients with schizophrenia.

Adult↗

PubMed2004

Speed and accuracy on tests of executive function in obsessive-compulsive disorder.

Slowness in obsessive-compulsive disorder (OCD) has been attributed to intrusive thoughts or meticulousness. Recent research suggests that slowness in OCD may be particularly evident on tests of executive function subserved by frontostriatal circuitry. In the present study, the speed and accuracy of responding on neuropsychological tests of executive functions and psychomotor speed were investigated in 27 non-depressed, unmedicated adults with OCD and 27 healthy controls. The only group difference was that patients took significantly longer to copy a complex geometric design than controls. This finding was unrelated to residual depression or overall OCD symptom severity. Results suggest that slowness in OCD may be most apparent on executive tests requiring self-initiated organizational strategies, consistent with frontostriatal abnormality.

Adult↗

PubMed2004

Executive dysfunction in attention-deficit/hyperactivity disorder: cognitive and neuroimaging findings.

Attention-deficit/hyperactivity disorder has been associated with a prominent disturbance of executive functions. There is no pathognomic neuropsychological profile for the disorder, however. Nonetheless, results of neuropsychological testing, in concert with other clinical information,provide a more comprehensive and detailed picture of the individual patient's cognitive and emotional strengths and weaknesses than a psychiatric diagnostic interview alone. This approach to the evaluation of ADHD therefore can provide a strong objective basis from which to make patient-specific recommendations for compensatory strategies and treatment. It should be noted, however, that although executive dysfunction in the form of impaired response inhibition remains the most prominent cognitive theory of ADHD, other theories have been put forth that also deserve further investigation. These include a disturbance in delay aversion (referring to intolerance for waiting) and impaired temporal processing, among others [79]. The neural substrates of executive dysfunction in ADHD have begun to be revealed by a growing body of structural and functional neuroimaging research. Although still in its infancy, neuroimaging of ADHD is pointing toward disruption of FSTC circuitry and the cerebellum as being central to the cognitive and motor abnormalities seen in the disorder. Further research using cognitive tasks assessing executive functions in combination with functional imaging techniques will provide further insight into the etiology of the disorder. It is expected that advances in structural and functional neuroimaging will yield valuable information that will facilitate the differential diagnosis of ADHD. Evidence cited suggests that psychostimulant medication can improve executive functions and their underlying FSTC circuitry. Furthermore, a recent study of adults with ADHD found significant improvements in organization skills and other symptoms of ADHD following cognitive remediation targeting several executive and emotional aspects of the disorder [80]. Additional studies investigating the effects of treatment on executive dysfunction and brain integrity in ADHD will be necessary to determine the degree to which the structural and functional brain abnormalities observed are mutable. Finally, because the myriad cognitive, behavioral and emotional symptoms in ADHD likely reflect the interplay of multiple cognitive and psychosocial factors, development of treatments for ADHD likely will require a multi-modal approach.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

Procedural and declarative memory in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) has been associated with frontostriatal abnormality. This has led to the hypothesis that the disorder is characterized by abnormality of procedural memory. However, evidence for either procedural or declarative memory disturbance has been mixed, and few studies have directly assessed both of these forms of memory in the same patient group. In the present study, we assessed encoding and retrieval in declarative memory using the Rey Auditory Verbal Learning Test (RAVLT), and procedural memory using the Pursuit Rotor Task, in 27 adults with OCD and 29 matched healthy controls. Groups did not differ with respect to salient demographic characteristics or memory on the RAVLT. In contrast, patients with OCD performed significantly better than controls during the early, but not later trial blocks of the Pursuit Rotor Task. This pattern of results indicates intact encoding and retrieval in declarative memory, but abnormally enhanced procedural memory during the early course of learning in OCD. These findings may be consistent with striatal overactivation observed in neuroimaging studies of OCD, as well as the prominent role of the striatum during early stages of procedural memory.

Adolescent↗

PubMed2004

Contribution of organizational strategy to verbal learning and memory in adults with attention-deficit/hyperactivity disorder.

Statistical mediation modeling was used to test the hypothesis that poor use of a semantic organizational strategy contributes to verbal learning and memory deficits in adults with attention-deficit/hyperactivity disorder (ADHD). Comparison of 28 adults with ADHD and 34 healthy controls revealed lower performance by the ADHD group on tests of verbal learning and memory, sustained attention, and use of semantic organization during encoding. Mediation modeling indicated that state anxiety, but not semantic organization, significantly contributed to the prediction of both learning and delayed recall in the ADHD group. The pattern of findings suggests that decreased verbal learning and memory in adult ADHD is due in part to situational anxiety and not to poor use of organizational strategies during encoding.

Adult↗

PubMed2004

Apathy in schizophrenia: reduced frontal lobe volume and neuropsychological deficits.

OBJECTIVE: Apathy is a common negative symptom in schizophrenia. The authors investigated neuropsychological performance and regional brain volumes in schizophrenia patients with high versus low levels of apathy. METHOD: Schizophrenia patients with low apathy levels (N=18) and high apathy levels (N=20) and 12 healthy comparison subjects completed neuropsychological testing as well as magnetic resonance imaging scanning to obtain lobar volumes after total intracranial volume was controlled. RESULTS: The high apathy group scored lower than comparison subjects on rapid visuomotor sequencing and verbal learning/recall. The high apathy group had lower performance IQ scores than the low apathy and comparison groups. Only the high apathy group showed significantly reduced bilateral frontal lobe volumes relative to comparison subjects; both schizophrenia patient groups showed bilateral temporal lobe volume reductions. CONCLUSIONS: The present findings are consistent with studies in other disorders showing frontal lobe involvement in apathy.

Adult↗

PubMed2004

Neurologic injury associated with CABG surgery: outcomes, mechanisms, and opportunities for improvement.

Neurologic injuries, whether subtle or overt, are a major source of morbidity secondary to coronary artery bypass graft (CABG) surgery. A comprehensive review of research in the area of neurologic injury is provided. We conclude this article by providing insight regarding areas requiring further investigation in order to reduce sustainably the risk of these iatrogenic events among patient undergoing CABG surgery.

Clinical Trials as Topic↗