Zachariah Campbell

A Meta-Analysis of Structural and Functional Brain Imaging in Dementia of the Alzheimer's Type: A Neuroimaging Profile

We conducted a quantitative review of the imaging literature using meta-analytic methodology to characterize further the magnitude of hippocampal deficit in probable Alzheimers disease (AD) and to determine whether other neuroanatomic structures in AD can better discriminate the disease from normal aging. Additionally, we parceled the discriminability of neuroanatomic structures by duration of disease to determine those structures most sensitive to AD in its early and late stages. One hundred twenty-one studies published between 1984 and 2000 met criteria for inclusion in the present analysis. In total, structural (i.e., CT and MRI) and functional (i.e., SPECT and PET) neuroimaging results from 3511 patients with AD, and 1632 normal healthy controls were recorded across meta-analyses. Our results include neuroimaging profiles for both early onset and longer duration patients with AD. In sum, these profiles yield a signature of diagnostic markers in both cortical and subcortical neuroanatomic areas. This signature is consistent with the clinical phenomenology of Alzheimers dementia and should aid in the positive identification of AD.

Quantitative evidence for distinct cognitive impairment in anorexia nervosa and bulimia nervosa

It is generally agreed that at least some aspects of abnormal eating behaviour is indeed due in part to disordered cognition. The accumulated literature illustrates cognitive impairment in patients with anorexia nervosa (AN) and bulimia nervosa (BN). Yet beyond being inconsistent, these independent studies also do not reveal the magnitude of impairment within and across studies and fail to give due consideration to the magnitude of impairment so as to understand the severity and breadth of impairment and/or differences in cognitive profiles between patients with AN and BN. Hence, the present review on the subject sought to articulate the magnitude of cognitive impairment in patients with AN and BN by quantitatively synthesizing the existing literature using meta-analytic methodology. The results demonstrate modest evidence of cognitive impairment specific to AN and BN that is related to body mass index in AN in terms of its severity, and is differentially impaired between disorders. Together, these results suggest that disturbed cognition is figural in the presentation of eating disorders and may serve to play an integral role in its cause and maintenance. Implications of these findings with respects to future research are discussed.

Memory impairment in now abstinent MDMA users and continued users: A longitudinal follow-up

The authors further investigated the functional consequences of continued neurotoxicity of (±)3,4-methylenedioxymethamphetamine (MDMA) use. Fifteen participants who were previously given a brief neuropsychological battery were tested for a third time 2 years after baseline. At 2 years, seven participants were still using MDMA, whereas eight participants had become abstinent from MDMA since 1-year testing. Current users demonstrated further declines in memory ability; former users improved on several memory measures or remained static in performance.

Utilizing Virtual Reality to Improve the Ecological Validity of Clinical Neuropsychology: An fMRI Case Study Elucidating the Neural Basis of Planning by Comparing the Tower of London with a Three-Dimensional Navigation Task

Virtual reality (VR) was used to create an ecologically valid spatial-navigation task in hand with functional magnetic resonance imaging (fMRI) to articulate the neural basis of planning behavior. A virtual version of a traditional planning measure, the Tower of London, was also developed to ascertain convergent and divergent validity in terms of planning behavior and functional neuroanatomy. This VR-fMRI case study experiment was performed at 3.0 Tesla on a young healthy male subject. The obtained image data suggest both convergent and divergent specificity between the two conditions in terms of location and overall intensity of activation. Overall, the present case study provides supportive evidence that the activity of various brain regions associated with planning tasks is largely modulated by the ecological validity of the measure being used. This finding may extend to all domains of inquiry in neuropsychological research and assessment when deductive conclusions are formulated on the results of neuropsychological test measures that could be considered contrived in nature.

Development of a Novel, Ecologically Oriented Virtual Reality Measure of Executive Function: The Multitasking in the City Test

A novel virtual reality executive function task (Multitasking in the City Test [MCT]) was developed with the aim of investigating planning and multitasking with ecological validity in mind in a normal population. Thirty healthy participants (21 females) completed a neuropsychological test battery that included the MCT along with standardized tests of executive and other cognitive functions. The sample performed within normal limits on the standardized tests. The MCT was performed successfully, although specific types of errors occurred frequently. Spearman correlation coefficients were computed between the various test measures. Only the plan score from the MCT was significantly associated with one of the executive function tests administered (Modified Six Elements Test), suggesting that both variables may be measuring a similar construct. Statistically significant correlations were also found between the MCT and the Trail-Making Test Part A and Judgment of Line Orientation, suggesting that “basic” cognitive functions such as information-processing speed and visuospatial skills are being tapped on the MCT. Preliminary evidence from this study suggested that the MCT may be an ecologically valid method of evaluating executive functioning. The clinical implications of these findings are discussed.

Ecologically Valid Assessment of Executive Dysfunction Using a Novel Virtual Reality Task in Patients with Acquired Brain Injury

The current investigation sought to further establish the psychometric properties and ecological validity of the Multitasking in the City Test (MCT) in a clinical population. Ecological validity was addressed via correlational analyses between performance on this test and a subjective measure of everyday executive functioning (Frontal Systems Behavior Scale; FrSBe). The sample was composed of 13 individuals (11 males) who suffered a stroke or traumatic brain injury. A neuropsychological test battery consisting of the MCT and common executive and nonexecutive measures was administered. The only executive function tests that were significantly related to the FrSBe were the MCT and a semantic fluency test. Compared with a sample of normal participants, the patient group produced better plans but completed fewer tasks on the MCT. Patients made similar types of errors as normals, although some of these errors occurred more frequently in the patient sample. This study demonstrated the ecological validity of the MCT and suggested that patients can be differentiated from healthy individuals by quantitative (i.e., number of errors) rather than qualitative (i.e., type of errors) aspects of performance. Further interpretation of MCT performance and comparison with existing executive function tests is discussed.

A comparison between a researcher-rated and a self-report method of insight assessment in chronic schizophrenia revisited a replication study using the SUMD and SAIQ

Previous research in schizophrenia has not consistently found concurrent validity between researcher-rated and self-report scales of insight. Differences in the correlations between the two types of scales have been found when order of administration is varied. The current study sought to replicate this earlier study in a sample of 21 patients with chronic schizophrenia who were given the same researcher-rated scale (Scale to Assess Unawareness of Mental Disorder; SUMD) and a different self-report measure (Self-Appraisal of Illness Questionnaire; SAIQ). A counterbalanced research design was employed. Significant correlations (p < 0.05) were found between the SUMD and SAIQ subscales in the SAIQ first group but not in the SUMD first group. The present study replicated earlier findings and provides further support for the importance of order of administration effects when evaluating concurrent validity between different types of insight scales. The reliability of insight scales may be substantially improved if a self-report insight scale is administered prior to a researcher-rated scale.

Scaffolded instruction remediates Wisconsin Card Sorting Test deficits in schizophrenia: A comparison to other techniques

This study compared the efficacy of two instructional techniques, scaffolding and direct instruction, with a practice control condition in the remediation of Wisconsin Card Sorting Test (WCST) deficits among 45 highly chronic schizophrenic patients. The extent to which learning of the WCST generalised to other cognitive tests, including an object sorting task, the Short Category Test, Trail Making and Stroop tests, was also examined. The affective experience of the subjects was assessed via Rosenbergs Self-Esteem Scale and the Positive and Negative Affect Schedule (PANAS). Subjects who received scaffolded instruction improved significantly in the number of WCST categories achieved. The improvement was sustained one month later. Generalisation to other cognitive tests was encouraging but limited. The scaffolded group improved in their selfesteem and maintained a high positive affect. These findings have implications for psychosocial and cognitive rehabilitation.

Neuropsychological differentiation of late-onset schizophrenia and dementia of the Alzheimer's type.

Late-onset schizophrenia and dementia of the Alzheimers type (DAT) often present with some pathological and behavioral commonalities. Specifically, both illnesses may involve varying degrees of delusional manifestation, apathy, lateral/third-ventricular enlargement, reduced frontal lobe activity, and hippocampal atrophy. Moreover, patients with either disease have shown comparable cognitive impairment on standardized neuropsychological tests. As such, a differential diagnosis of the 2 disorders on the basis of such testing can prove to be difficult. This study evaluated the neuropsychological test results of 32 patients with late-onset schizophrenia and 32 patients with DAT to distinguish the tests that best differentiate the 2 disorders. Results indicate that the Wechsler Adult Intelligence Scale-Revised Similarities subtest and the California Verbal Learning Test (both short- and long-delay free recall) correspond to sensitive diagnostic neuropsychological measures. This investigation was preliminary in nature, and should aid in the development of a definitive differential profile.

Response latency in Canis familiaris: mental ability or mental strategy?

Animal studies of cognitive aging typically use measures of response accuracy (RA) to evaluate cognitive function, which declines with age. Human aging studies, by contrast, frequently measure response latency (RL), with faster responses being indicative of superior performance. To examine the influence of age on RL in an animal model, the authors assessed RA with RL in young and aged beagle dogs (Canis familiaris) tested on a 3-component delayed nonmatching-to-position task, which comprised 3 subtests. Young dogs displayed significantly slower RLs and higher RAs and showed RL slowing with greater complexity, compared with aged dogs. In addition, the slower responding young dogs made fewer errors. Thus, RL appears to reflect the learning strategy applied, rather than the level of mental ability.