Biomedical subjects

K I Bolla

Publications and source records attributed to K I Bolla.

33 records · Page 2Linked to original sources

PubMed1994

Neurologic health outcomes and Agent Orange: Institute of Medicine report.

The National Academy of Sciences' Institute of Medicine conducted an independent scientific investigation to evaluate the strength of evidence for human health effects among veterans exposed to herbicides used in Vietnam and to suggest future research recommendations. Neurologic domains where multiple studies had been performed in military, occupational, or environmental situations were (1) cognitive and neuropsychiatric effects, (2) motor/coordination dysfunction and other central nervous system disorders, and (3) peripheral neuropathy. In all categories, no strong evidence established an association between herbicides used in Vietnam and clinical neurologic disorders. Methodologic weaknesses, long durations between exposure and assessments, and poor exposure measures limited many studies. The committee concluded that the available evidence was insufficient to determine an association between neurologic disorders and exposure to herbicides used in Vietnam. Neurotoxicologic studies available did not suggest strong biological plausibility for neurologic alterations related to herbicide exposure. Furthermore, given the large uncertainties in the epidemiologic studies reviewed and inadequate control for important confounders, the committee could not quantify a degree of risk for neurologic disorders from herbicide exposure likely to be experienced by Vietnam veterans. Although not part of the neurologic report, the risk of brain tumors was considered in the cancer analysis, and the committee concluded that there is limited/suggestive evidence of no association between exposure to herbicides and brain tumors.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1993

Decrements in neurobehavioral performance associated with mixed exposure to organic and inorganic lead.

In 1990, 222 current employees of a chemical facility in the eastern United States that manufactured tetraethyl lead were administered a neurobehavioral test battery, tests of olfactory function and peripheral vibration threshold, and questionnaires that assessed neuropsychiatric symptoms. A cumulative variable of exposure to inorganic and organic lead was derived from 12 years of personal industrial hygiene sampling data and an occupational history interview that assessed work in each of 29 exposure zones in the lead area. The range of assigned exposure intensities in these 29 zones was 4-119 micrograms/m3 for organic lead and 1-56 micrograms/m3 for inorganic lead. Cumulative lead exposure and exposure duration were defined as categorical variables (four groups) in multiple linear regression models. The adjusted mean differences in neurobehavioral test scores were estimated by comparing the average scores of the moderate, high, and highest exposure groups with the low exposure (reference) group. After adjustment for premorbid intellectual ability, age, race, and alcohol consumption, neurobehavioral test scores were poorer as measures of both cumulative lead exposure and exposure duration increased; many of the associations evidenced dose-response relations. Associations were observed in most cognitive and functional domains tested, but were most common in two domains: manual dexterity and verbal memory/learning. On the affected neuropsychologic measures, the groups with the highest exposure averaged scores 5-22% lower than those of the reference groups. Overall, the data revealed generally consistent and coherent associations between two measures of lead exposure and poorer neurobehavioral test performance.

Adult↗

PubMed1992

Neurocognitive effects of aluminum.

The neurocognitive effects of aluminum (Al) were studied in 35 hemodialysis patients. Higher Al levels were associated with a decline in visual memory. As Al levels increased, patients with lower vocabulary scores (a measure of premorbid intelligence) showed a decline in attention/concentration, frontal lobe functions, and on several neurocognitive measures, while those with higher vocabulary scores revealed no Al-related decline. These results suggest that individuals with lower verbal intelligence may possess less well-developed compensatory strategies to overcome the neurocognitive effects associated with Al. These data also indicate that Al is neurotoxic and, therefore, potential sources of environmental Al should be identified and eliminated.

Adult↗

PubMed1992

The Milan Automated Neurobehavioral System. Age, sex, and education differences.

The Milan Automated Neurobehavioral System (MANS) has been used in field studies to measure effects of toxicants on the central nervous system. The battery has not been deemed appropriate in clinical settings because of the paucity of available norms. In this study, 236 (151 men, 85 women) healthy 39- to 94-year-olds were given the MANS as part of a comprehensive neurobehavioral evaluation. The subtests were simple visual reaction time, digit symbol substitution, serial digit learning, and Benton visual retention. Age and years of education accounted for a significant proportion of the variance in all four subtests. In two of the subtests (simple visual reaction time and Benton visual retention) sex also accounted for a significant proportion of the variance. Age-, sex-, and years of education-specific normative values are presented for healthy persons aged 50 to 79 years.

Adult↗

PubMed1991

Memory complaints in older adults. Fact or fiction?

Complaints of poor memory by patients may be an early symptom of a pathologic process like Alzheimer's disease. It is therefore important to determine if patients' complaints of memory impairments are an accurate reflection of real memory disturbance. The relationship between memory complaints (metamemory) and objective memory performance, mood, age, verbal intelligence, and sex was examined in a group of 199 healthy, community dwelling adults (39 to 89 years old). Memory complaints demonstrated a stronger association with depressed mood than with performance on memory tests. Increasing reports of depressive symptoms were associated with more overall memory complaints. Verbal intelligence, age, and sex also contributed to memory complaints. Patients with higher verbal intelligence reported fewer complaints and placed less emphasis on forgetting. Older individuals reported greater frequency of forgetting and greater frequency of using memory techniques. Specific types of memory complaints, seriousness of forgetting, and types of memory aids employed are also described. These results showed that self-rating of memory disturbance by older adults may be related more to depressed mood than to poor performance on memory tests.

Adult↗

PubMed1991

Dose-related subclinical neurobehavioral effects of chronic exposure to low levels of organic solvents.

One hundred eight-seven workers (mean age +/- SD; 42 +/- 8.8 years) in two paint manufacturing plants were examined to determine if sustained low-level exposure to mixed organic solvents resulted in the painters' syndrome (a psycho-organic syndrome). The test battery consisted of a medical and occupational questionnaire, the Present State Examination, the Zung Depression Scale, the Scandinavian Questionnaire 16, a neuropsychological battery, and vibration thresholds. Solvent exposure, expressed as total hydrocarbon of combined selected solvents, was quantitated using 13-15 years of personal breathing zone samplings. Linear regression analysis controlling for several confounding variables demonstrated significant correlations between increasing exposure to mixed organic solvents and neurobehavioral performance for vibration threshold and several neuropsychological tests. Dose-related effects of chronic solvent exposure on neurobehavioral outcomes (all subclinical) were shown, but "typical" symptoms characteristic of the painter's syndrome were not found.

Adult↗

PubMed1991

Comparison of computerized and examiner-administered neurobehavioral testing techniques.

To better understand the relationship of newly developed computerized neurobehavioral tests to their examiner-administered counterparts, performance on four pairs of tests was compared among 185 solvent-exposed workers in the paint manufacturing industry. Two approaches to the comparison of the test methods (computer or examiner) were employed: (1) the multitrait-multimethod correlation matrix and (2) linear regression modeling of the difference scores between pairs of tests (same functional domain, different test formats). The data revealed that the validity criteria of the multitrait-multimethod technique were met for the tests of simple visual reaction time and attention-concentration (digit symbol substitution). Linear regression analyses demonstrated that the digit symbol substitution and visual memory test pairs were differentially affected by age, vocabulary, solvent exposure, or manual dexterity. Overall, this latter approach holds promise as a means of understanding test format similarities and differences.

Adult↗

PubMed1991

Solvent-associated olfactory dysfunction: not a predictor of deficits in learning and memory.

OBJECTIVE: The aim of the study was to evaluate associations between olfactory dysfunction and aberrations in learning and memory after chronic occupational exposure to mixed hydrocarbon solvents. METHOD: This was a cross-sectional, epidemiologic study of 187 paint manufacturing workers. The authors administered quantitative tests of olfactory function (the University of Pennsylvania Smell Identification Test) and neurobehavioral function (eight computer- and examiner-administered tests of learning and memory) to workers for whom detailed information was available on lifetime occupational exposure to solvents. RESULTS: Olfactory function test scores were positively correlated with performance on seven of eight of the tests of learning and memory in bivariate analyses. After adjustment for important confounding variables (i.e., age, vocabulary score, and cumulative exposure to hydrocarbon solvents) with multiple linear regression, olfactory function scores predicted performance only on the Wechsler Memory Scale Delayed Logical Memory test. CONCLUSIONS: Overall, the data did not reveal that olfactory dysfunction was correlated with decrements in various memory functions.

Adult↗

PubMed1991

Dihydropteridine reductase activity: lack of association with serum aluminum levels and cognitive functioning in patients with end-stage renal disease.

Although increased levels of aluminum (Al) are present in patients with dialysis encephalopathy (DE), it is unclear if the association is causal. The enzyme dihydropteridine reductase (DHPR) plays a critical role in neurotransmitter formation and its activity. Elevated levels of Al are reported to decrease DHPR activity, which would alter neurotransmitter metabolism, thus producing DE. We examined the association between erythrocyte DHPR activity and Al levels, attention/psychomotor skills, and depression in a group of 21 patients with end-stage renal disease. DHPR activity was not related to Al level, mental status, psychomotor ability, or depression score. After administration of deferoxamine (an Al chelating agent), Al level increased significantly but DHPR activity remained the same. Our results suggest that the mechanism for the development for DE does not involve alterations of neurotransmitter metabolism caused by Al-mediated reductions in DHPR activity.

Adult↗

PubMed1991

Neuropsychological assessment for detecting adverse effects of volatile organic compounds on the central nervous system.

Because there are no direct biological markers for the substances implicated in indoor air exposure, it is impossible to directly measure if an individual or group of individuals has been exposed to a potentially neurotoxic substance in the workplace. Behavioral changes may be the earliest and only manifestation of central nervous system (CNS) effects and are often too subtle to be revealed by routine physical or neurological examination. Neuropsychological techniques are sensitive to subtle behavioral/cognitive changes that can result from exposure to neurotoxins. These techniques consist of oral and written tests that are administered by a trained examiner on a one-to-one basis. In general, a wide variety of cognitive domains are evaluated. The typical battery generally includes assessing orientation, attention, intelligence, language, visual memory, verbal memory, perception, visuoconstruction, simple motor speed, psychomotor speed, and mood. As with most assessment techniques, the neuropsychological methods have limitations. One major drawback is the availability of appropriate norms that are used to compare the results of a specific individual. Because these tasks are greatly affected by age, intelligence, and in some instances sex, the availability of appropriate norms is mandatory to determine if the CNS has been effected. Although neuropsychological tests are sensitive to the presence of CNS involvement, they are not specific. Patterns of performance seen with specific instances of neurotoxic exposure may also be seen with a number of other diseases of the CNS such as dementia, cerebrovascular disease, hydrocephalus, or normal aging. In addition, neuropsychiatric symptoms such as anxiety and/or depression are often manifested as cognitive difficulties that will mimic the cognitive dysfunction seen with toxicity of the CNS.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗

PubMed1990

Predictors of verbal fluency (FAS) in the healthy elderly.

The Verbal Fluency Task (FAS), sensitive indicator of brain injury, was examined in a population of healthy elderly (N = 199, aged 40 to 89 years). The present study was conducted to examine the relative contributions of age, sex, education, verbal intelligence, and specific cognitive abilities to FAS performance. Significant effects were found for vocabulary and sex, although no aging effect was found. Separate norms for sex and level of verbal intelligence are presented. Results indicated that ability to quickly organize information and formulate effective recall strategies played a critical role in good FAS performance.

Adult↗

PubMed1990

Solvent-associated decrements in olfactory function in paint manufacturing workers.

To assess the effects of low-level organic solvent exposure on olfactory function, a cross-sectional study in paint manufacturing workers was undertaken. Workers in two paint manufacturing facilities (N = 187) were tested using the University of Pennsylvania Smell Identification Test (UPSIT), a standardized, quantitative test of olfactory function. Industrial hygiene air samples over the past 13-15 years revealed that average solvent exposures in these plants were 2-40% of the existing threshold limit values for the three chemicals measured. Stratification by smoking status revealed evidence of dose-related decrements in olfactory function (p = .01) only in non-smokers. Furthermore, those nonsmoking workers in the highest exposure category had UPSIT scores below the fifth percentile for their age. These results suggest that solvents may cause nervous system dysfunction at lower levels than previously suspected, and that the olfactory system may be a critical target organ for the neurotoxic effects of solvents and other chemicals.

Adult↗

PubMed1990

Subclinical neuropsychiatric effects of chronic low-level solvent exposure in US paint manufacturers.

In the present study, 187 workers at two US paint manufacturing plants were assessed for symptoms of painters syndrome using the Zung Depression Index, Scandinavian Questionnaire 16, and the Present State Exam. No significant associations were found between solvent exposure and total scores, although a sum of individual questions related to depression on the Present State Exam was found to be related to both health status and exposure. The clinical relevance of these findings is discussed. Overall, exposure was not associated with the constellation of symptoms characteristic of the painters' syndrome.

Adult↗

PubMedDate not supplied

Simple visual reaction time in organolead manufacturing workers: influence of the interstimulus interval.

The authors conducted this investigation to study the effects of interstimulus interval duration for a given simple visual reaction time trial on the relationship between lead exposure and reaction time. Organolead manufacturing workers (n=222) and nonexposed referents (n=62) were administered a neurobehavioral test battery that included simple visual reaction time. Simple visual reaction time was measured over 44 trials; interstimulus intervals ranged from 1 to 10 s in a randomly generated sequence that was identical for all study subjects. Mean reaction times for both lead-exposed and nonexposed subjects were longest for interstimulus intervals of 1 and 2 s. Mean reaction times in response to moderate (4-6 s) and long (7-10 s) interstimulus intervals were mainly associated with lead exposure; this association led the authors to suggest that interstimulus interval duration modifies the relationship between lead exposure and simple visual reaction time performance. In simple visual reaction time protocols, stronger associations between reaction time and lead exposure may be found if the analysis trials are separated with interstimulus intervals of less than 3 s duration.

Age Factors↗

PubMedDate not supplied

Use of neuropsychological testing in idiopathic environmental testing.

Individuals with idiopathic environmental intolerance (IEI) report fatigue, headaches, weakness, malaise, decreased attention/concentration, memory loss, disorientation, confusion, and psychological disturbances. These neurobehavioral symptoms may be a sign of possible alterations in the central nervous system (CNS). The evaluation of neurobehavioral functioning using standardized testing provides a surrogate measure of integrity of the CNS. However, the interpretation of neuropsychological test results must be made cautiously since this technique is extremely sensitive, but not specific. Abnormal test results could be due to a neurological disorder, a medical disorder, or a neuropsychiatric disorder. Therefore, when evaluating patients who present with symptoms of IEI, abnormal neurobehavioral results should not be attributed routinely to environmental chemical exposure until other causes are systematically ruled out.

Brain Diseases↗