Jim Hom

Neuropsychological Correlates of Gulf War Syndrome

As part of a comprehensive multispecialty project, the present study reports on the neurocognitive and psychological function of veterans who report Persian Gulf War-related symptoms. The neuropsychological and psychological performances of 26 ill Gulf War veterans were compared to 20 well veterans from the same military unit. Neurocognitive functions assessed included intelligence, abstraction and problem-solving, attention and concentration, memory and learning, language and visual-spatial function, and sensorimotor abilities. Psychological function was measured by self-report questionnaires. Results indicated global and consistently poorer intellectual and neurocognitive function among the ill veterans compared to the control veterans. A generalized pattern of neuropsychological deficit was evident for the ill veterans. Psychological profiles of the ill veterans were similar to those in general medical patients. Based on these findings and results from the multispecialty investigation, we conclude that some of the ill veterans have experienced neurotoxic injury resulting in chronic neuropsychological impairment that is related to their service in the Persian Gulf War.

Generalized cognitive function after stroke

The present investigation was designed to determine the effect of cerebrovascular lesions upon general neuropsychological function. The performances of 60 patients with lateralized or diffuse cerebrovascular lesions were compared to 20 controls on cognitive and intellectual measures. Multivariate analyses indicated markedly poorer performances by the cerebrovascular groups on measures of generalized cerebral function, and no differences on such measures were found between the left- and right-damaged groups. The lateralized CVD groups demonstrated a differential tendency towards lower performances on VIQ for the left group and on PIQ for the right group. The results indicate significant neuropsychological impairment which extends beyond the expected lateralized dysfunctions, or selected deficits, associated with the damaged hemisphere. These findings indicate the importance of evaluating generalized as well as specific cognitive functions in clinical assessment of cerebrovascular lesions.

Single photon tomography in Alzheimer's disease and the dementias.

Measurements of brain blood flow has evolved over the past 50 years, and during the latter half of that time radionuclide techniques have been used to study this important function. Using Xenon 133 and scintillation multiprobe systems, several teams of investigators measured regional cerebral blood flow (rCBF), and noted that under many circumstances it could be equated with local brain physiological activity. The dementias were investigated using the scintillation multiprobe method, and posterior flow deficits were described in patients who were thought to have Alzheimers disease. The multiprobe technique gave way first to planar, and then tomographic imaging, with initial favorable results achieved by positron emission tomography (PET). Soon investigators learned to measure rCBF with single-photon emission computed tomography (SPECT) using high-sensitivity systems and 133Xe as a tracer, or high-resolution systems with 123I-iodoamphetamine (IMP), and later, 99mTc-HMPAO. Three-dimensional tomographic imaging shows to advantage the flow patterns that characterize Alzheimers disease, with rCBF reductions in temporal, parietal, and sometimes frontal areas, as opposed to randomly distributed deficits in multiinfarct dementia, reduced frontal flow in entities such as Picks disease, and others. Herein we will review our own experience with high-sensitivity rCBF SPECT in 119 patients with dementia, and with high-resolution SPECT, using a new, three-camera scanner and 99mTc-HMPAO in an additional 39 patients. SPECT rCBF study of patients with dementia and Alzheimers disease, will aid in separating patients with untreatable Alzheimers from those patients who may have treatable causes of dementia, and will be useful in evaluating experimental drugs for the treatment of Alzheimers disease.

The effect of acetazolamide on regional cerebral blood flow in patients with Alzheimer's disease or stroke as measured by single-photon emission computed tomography

Regional cerebral blood flow (rCBF) was assessed in 35 patients with possible or probable Alzheimers disease (AD) and in 16 patients known to have had at least one stroke. Patients were evaluated before and after the administration of 1 g acetazolamide (ACZ) by means of a rotating four-detector single-photon emission computed tomograph (SPECT) and inhaled Xe-133. RCBF values in mL/minute/100 g were derived from eight cortical regions of interest (ROI), and from the whole transverse section as a measure of whole brain flow (WBF). ROI/WBF ratios were calculated for each ROI in paired determinations done before and 15 minutes after the administration of ACZ. Results were compared with those previously obtained in a study of 15 normal, healthy volunteer subjects. ROI/WBF ratios greater than 2 standard deviations (SD) below the mean for a given ROI in the normal group were regarded as probably abnormal, whereas ratios greater than 4 SD below the mean were considered definitely abnormal. After ACZ administration, the number of ROI greater than 2 SD below the normal mean decreased significantly in the AD group and was unchanged in the stroke patients. However, the number of ROI/WBF ratios greater than 4 SD below the normal mean fell in the AD group and rose in the stroke group, with the difference in behavior highly statistically significant. Thus, the response of low-flow areas to ACZ differs in AD and in stroke, which could be of ultimate diagnostic significance.

Forensic Neuropsychology: are we there yet?

Forensic Neuropsychology is a new and rapidly evolving subspecialty of clinical neuropsychology that applies neuropsychological principles and practices to matters that pertain to legal decision-making. Forensic neuropsychologists provide the trier of fact with specialized information regarding brain-behavior relationships. The primary responsibility of the forensic neuropsychologist is to provide information based on scientifically-validated neuropsychological principles and clinical methodology that is pertinent to the Forensic Question at hand-which is not just whether the patient has dysfunction, but whether the dysfunction results from the event under consideration. To best answer the Forensic Question, the neuropsychologist must use a methodology that has been scientifically-validated on brain-impaired individuals, and can distinguish various brain conditions from each other as well as from normal variation. The methodology must be able to determine whether any dysfunction found is, in fact, the result of a neurological condition as opposed to non-neurological, psychological, or even factitious disorders. This paper discusses neuropsychological methodology in the context of forensic application and the requirements of the legal process and illustrates these issues with case examples.

Cognitive deficits in asymptomatic first-degree relatives of Alzheimer's disease patients

The present study was designed to determine whether neuropsychological deficits exist in asymptomatic first-degree relatives of Alzheimers disease (AD) patients. The neuropsychological performances of 20 first-degree asymptomatic relatives of NINCDS-ADRDA diagnosed AD patients were compared to 20 normal controls without family history of AD. Cognitive functions assessed included intelligence, memory, overall brain function, verbal learning, and language and constructional abilities. Significant statistical differences were found between the groups across several cognitive areas indicating lower functioning in the first-degree relatives of AD patients. Fifty percent of the first-degree subjects but only 20% of controls showed a pattern of significant neuropsychological deficit. The results demonstrate neuropsychological deficits in asymptomatic first-degree relatives of AD patients, suggesting that preclinical markers for AD may be present long before the clinical manifestation of the disease.

The Houston Conference revisited

This paper presents a review and critique of the Houston Conference on Specialty Education and Training in Clinical Neuropsychology, together with an informal summary of opinions of a number of neuropsychologists. Issues regarding the role of the Clinical Neuropsychology Synarchy (CNS) and the applicability of the conference policies are offered. Several deficiencies and limitations of the policy statement are discussed. An informal survey of neuropsychologists interested in the Houston Conference indicates rather different opinions concerning the training and education of neuropsychologists. It is our contention that the results of the Houston Conference can only be considered controversial at best and that there is still much diversity of opinion in the field regarding the proper training of neuropsychologists. We hope to stimulate further discussion and greater involvement of the profession before final criteria for education and training are developed and adopted.

Left cerebral dominance for bilateral simultaneous sensory stimulation

Hom and Reitan (1982) reported findings with respect to sensorimotor deficits in groups with lateralized cerebral lesions, but evaluated the results only within a framework that related cerebral dominance to deficits that resulted from lateralized lesions. Some of the variables they studied, however, depend upon evidence of retention of functions by one hemisphere under conditions of distracting input. While the right cerebral hemisphere appears to be dominant for tactile-perceptual abilities in terms of resulting deficits, the present study suggests that the left cerebral hemisphere is dominant for certain non-language functions that reflect maintenance of sensory-perceptual abilities under conditions of distracting stimuli.

Comparability of the Computerized Halstead Category Test with the Original Version

The Halstead Category Test-Computer Version (HCT-CV) was developed with the goal of adapting the HCT to the computer while maintaining all essential features of the original test. We compared the HCT-CV results from clinical neuropsychological evaluations of 25 patients who were matched on a pairwise basis with 25 patients previously tested with the original version. Matching was done on age, education, and diagnosis. Results of group comparisons showed that the HCT-CV performed comparably with the original version, with mean score differences of <2 points. Correlations with the other subtests from the Halstead-Reitan Neuropsychological Test Battery were also found to be comparable. Results suggest that the HCT-CV can be considered a satisfactory and comparable version of the HCT, while providing advantages in terms of ease of use and portability.

Neuropsychological function in type 2 diabetes mellitus

ABSTRACT Type 2 diabetes mellitus (DM) is a major and growing health problem. Brain-related effects of type 2 DM have been studied in several ways over the past few decades. Results have shown effects on brain structure, incidence of dementia, and impairment of various cognitive functions. The present study examined a sample of clinically-referred patients with type 2 DM and compared them with a sample of control patients who were matched on a pairwise basis on age, education, and gender. Each patient was tested using a comprehensive, integrated neuropsychological test battery. Results showed a pattern of generalized and specific neuropsychological dysfunction affecting a broad range of neurocognitive and sensorimotor abilities. However, no differences were found on measures of attention/concentration, memory, or abstract reasoning. Nevertheless, the DM group consistently performed worse on all measures. The DM group’s score on a summary measure of neuropsychological function (GNDS) reflected moderate brain-related impairment. A neurocognitive profile is identified that may help clinicians understand their DM patients.