Biomedical subjects

I R Bell

Publications and source records attributed to I R Bell.

64 records · Page 4Linked to original sources

PubMedDate not supplied

Time-dependent sensitization of heart rate and blood pressure over multiple laboratory sessions in elderly individuals with chemical odor intolerance.

In this study, we tested the hypothesis that low-level chemical odor intolerance (i.e., "cacosmia") is a manifestation of heightened sensitizability to environmental stimuli. We examined supine heart rate and blood pressure of elderly individuals, who were classified as either having a higher degree of chemical odor intolerance (n = 12) or a lower degree of chemical odor intolerance (n = 13), upon awakening in a sleep research laboratory on 6 different days during an 8-wk protocol. During the 2 initial wk, they consumed a customary baseline diet (including ad lib milk and other dairy products), followed by 3 wk each of nondairy-containing and dairy-containing diets in randomly assigned, counterbalanced order. Measurements were made on 3 pairs of successive days, distributed over a 6-wk period, and on which different diets were consumed. The high-intolerance group had significantly higher mean supine systolic and diastolic blood pressures than did the low-intolerance group. Although subjects consumed milk products during both the initial baseline and subsequent dairy diet periods, the high-intolerance group had significantly higher heart rates and diastolic blood pressures later in the study than at baseline, especially when they were on the dairy diet. In contrast, the cardiovascular measures of the low-intolerance group lowered on average with time. The high-intolerance subjects had an increased mean diastolic blood pressure on the second days versus the first days in the laboratory (averaged across all diets). Collectively, the data suggest that elderly individuals with a high degree of chemical odor intolerance evidence (a) increased sympathetic tone in the cardiovascular system at rest over multiple measurements; and (b) greater sensitizability and/or lesser habituation of heart rate and diastolic blood pressure over time as a function, in part, of repeated environmental stressor exposures (i.e., a novel laboratory contextual setting and/or specific dietary constituents). Consistent with a sensitization model, the findings emphasize the need for two or more identical sessions at least 24 h apart in physiological studies of individuals with a high degree of intolerance for chemical odors versus normal individuals. The results of the blood pressure observations suggest that the possibility of abnormally labile autonomic function and cognitive sequelae in individuals with a high degree of intolerance for chemical odor increases with age.

Aged↗

PubMedDate not supplied

Increased cardiopulmonary disease risk in a community-based sample with chemical odor intolerance: implications for women's health and health-care utilization.

Chemical intolerance, or reported illness from odors of common environmental chemicals (e.g., car exhaust, pesticides), is emerging as an important environmental and public health-care issue. Epidemiologic methods provide relevant heuristic devices for studies of complex disorders, such as chemical intolerance. The authors examined personal and reported parental cardiopulmonary disease prevalence rates in a community sample of chemically intolerant and control individuals. A county government (Tucson, Arizona) employee and kin subset (N = 181; 113 households) completed standard health questionnaires. Investigators determined chemical intolerance (n = 41/181) from self-reports of individuals who felt "moderately" to "severely" ill from exposure to at least three of five chemicals (i.e., car exhaust, pesticides, paint, new carpet, and perfume) on a Chemical Odor Intolerance Index. The authors chose the control group (n = 57/181) on the basis of self-reports of "never" feeling ill on the Chemical Odor Intolerance Index. The chemically intolerant group, which primarily comprised women (78% versus 51% of controls, p < .05), was significantly more likely to report-and to have sought--medical attention for heart problems, bronchitis, asthma, and pneumonia. Reports of heart problems in the chemically intolerant index cases and the occurrence of heart disease in both of their parents were significant (Fisher's p < .05). The chemically intolerant individuals were also significantly more likely to report maternal histories of chest problems (e.g., inhalant allergens, tuberculosis) than controls. The findings of the study suggested that the chemically intolerant individuals (a preponderance of whom were women [sex-related risk]) were more likely to have (a) reported cardiopulmonary problems (i.e., greater health risk); (b) actively sought medical care for these problems (i.e., increased medical utilization); and (c) reported more parental illnesses-particularly heart disease, asthma, and diabetes (i.e., genetic risk). Additional community-based studies of chemical intolerance are needed.

Adult↗

PubMedDate not supplied

Is allergic rhinitis more frequent in young adults with extreme shyness? A preliminary survey.

Previous studies suggest that social anxiety, allergies and distressed affect may be interrelated in some persons. For example, extremely introverted patients experience a poorer course and outcome of allergies as well as greater degrees of distressed affect such as depression and anxiety than do extraverts. Patients with affective disorders have a higher prevalence of atopic allergy than the general population; families of patients with panic disorder and major depression have the highest frequency of shy children. Preliminary investigation also indicate that behaviorally inhibited Caucasian children (initially shy and cautions in unfamiliar situations) and their families have more allergies, especially hay fever, than do uninhibited, socially outgoing children. The present survey evaluated the frequency of self-reported shyness. The most introverted subjects had significantly higher scores on self reports of depression, fearfulness, and fatigue, as well as a higher prevalence of hay fever. The data support the possibility of a distinct subgroup of shy individuals with concomitant vulnerability to specific allergies and affective disorders.

Adolescent↗

PubMedDate not supplied

Positive perceptions of parental caring are associated with reduced psychiatric and somatic symptoms.

OBJECTIVE: In a previous 35-year follow-up investigation to the Harvard Mastery of Stress Study, positive ratings of parental caring obtained in healthy male college students were found to be predictive of substantially reduced disease incidence (including cardiovascular disease, ulcers, and alcoholism) in mid-life. The present cross-sectional study examined the relationship between perceptions of parental caring, current psychiatric and somatic symptoms, and defensiveness, in a University of Arizona sample of females and males. METHOD: The Harvard Parental Caring Scale (HPCS), the SCL90R, and the Marlowe-Crowne (MC) scale (a measure of defensiveness) were administered to 398 students at the University of Arizona. RESULTS: Cronbach alphas were .83 for HPCS ratings of mothers and .88 for fathers. High HPCS ratings were associated with reduced symptoms reports in both females and males (p < .00002). Ratings of HPCS showed a small correlation with defensiveness (r = .141). The relationship between HPCS and symptoms was strongest in the least defensive subjects. CONCLUSIONS: Positive perceptions of love and caring from parents, typically the most important source of social support for children, are associated with reduced psychiatric and somatic symptoms. Defensiveness may play a protective role psychologically (but not necessarily physiologically) in reducing the conscious awareness of symptoms accompanying low perceptions of parental love and caring.

Adolescent↗

PubMedDate not supplied

Neural sensitization model for multiple chemical sensitivity: overview of theory and empirical evidence.

This paper summarizes theory and evidence for a neural sensitization model of hyperresponsivity to low-level chemical exposures in multiple chemical sensitivity (MCS). MCS is a chronic polysymptomatic condition in which patients report illness from low levels of many different, structurally unrelated environmental chemicals (chemical intolerance, CI). Neural sensitization is the progressive host amplification of a response over time from repeated, intermittent exposures to a stimulus. Drugs, chemicals, endogenous mediators, and exogenous stressors can all initiate sensitization and can exhibit cross-sensitization between different classes of stimuli. The properties of sensitization overlap much of the clinical phenomenology of MCS. Animal studies have demonstrated sensitization to toluene, formaldehyde, and certain pesticides, as well as cross-sensitization, e.g., formaldehyde and cocaine. Controlled human studies in persons with self-reported CI have shown heightened sensitizability in the laboratory to nonspecific experimental factors and to specific chemical exposures. Useful outcome measures include spectral electroencephalography, blood pressure, heart rate, and plasma beta-endorphin. Findings implicate, in part, dopaminergic mesolimbic pathways and limbic structures. A convergence of evidence suggests that persons with MCS or with low-level CI may share some characteristics with individuals genetically vulnerable to substance abuse: (a) elevated family histories of alcohol or drug problems; (b) heightened capacity for sensitization of autonomic variables in the laboratory; (c) increased amounts of electroencephalographic alpha activity at rest and under challenge conditions over time. Sensitization is compatible with other models for MCS as well. The neural sensitization model provides a direction for further systematic human and animal research on the physiological bases of MCS and CI.

Autonomic Nervous System↗

PubMedDate not supplied

EEG sensitization during chemical exposure in women with and without chemical sensitivity of unknown etiology.

This study tested the sensitization model proposed by Bell et al. [Bell I.R., Miller C.S. and Schwartz G.E. An olfactory-limbic model of multiple chemical sensitivity syndrome: possible relationship to kindling and affective spectrum disorders. Biol. Psychiatry 1992: 32: 218-242] to study chemical sensitivity. The sensitization model indicates that a pharmacological stimulus or a traumatic event which elicits a strong response can sensitize limbic and/or mesolimbic pathways; and subsequent less intense trauma or stimuli, in the same or different modality, can elicit an amplified response. Three groups of subjects were tested: (1) women who reported chemical sensitivity and no sexual abuse (chemically sensitive, CS); (2) sexually abused (SA) women without chemical sensitivity; and (3) healthy women without chemical sensitivity or sexual abuse history (normal, N). All subjects were exposed to odorant and nonodorous control stimuli once a week for 3 weeks. Electroencephalographic activity was recorded while subjects sniffed the odorant and control stimuli. Results of the study revealed that both the CS and the SA group showed electroencephalogram (EEG) alpha sensitization across experimental sessions, while the N group showed little change over time. Additionally, EEG findings revealed that the CS group generated significantly greater alpha activity than the other two groups. Finally, while the groups were different on measures of psychological distress, these differences did not diminish the EEG findings. In summary, these findings suggest that intermittent exposure to chemicals elicits sensitization in CS and SA women without chemical sensitivity, supporting our expectations that chemical sensitivity is, in part, a manifestation of time-dependent sensitization (TDS). Additionally, these EEG findings indicate that CS women are unlike SA and healthy women in the amount of EEG alpha activity they generate. Finally, these findings indicate that psychological factors as assessed in this study do not explain electrophysiological differences between chemically and non-chemically-sensitive women.

Drug Hypersensitivity↗

PubMedDate not supplied

Odor sensitivity and respiratory complaint profiles in a community-based sample with asthma, hay fever, and chemical odor intolerance.

This is a community-based study of odor sensitivity and respiratory complaints for persons reporting asthma (n = 14/141), hay fever (n = 72/140), and chemical odor intolerance (CI) (n = 41/181). CI, a symptom of multiple chemical sensitivity (MCS), was determined from self-ratings of feeling 'moderately' to 'severely' ill using the Chemical Odor Intolerance Index (CII). Index odors included perfume, pesticide, drying paint, new carpet odor, and car exhaust. Six additional odors [natural gas, disinfectants, chlorinated water, room deodorizers, and environmental tobacco smoke (ETS)] were also assessed in the health and environment survey. Asthmatics reported feeling 'frequently' to 'almost always' ill from the CII index odors of drying paint, new carpet odor, perfume, and cleaning agents compared to nonasthmatics. People with hay fever documented feeling 'frequently' to 'almost always' ill from pesticides, drying paint, and car exhaust compared to individuals without hay fever. The CI cited illness from air freshener, natural gas and chlorinated water, in addition to the index odors of perfume, paint, pesticides, new carpeting and auto exhaust. All three groups were significantly more likely to report feeling ill from ETS. People with asthma were significantly more likely to report lower lung complaints, such as wheeze and dyspnea. People with hay fever cited more chest tightness. The CI were significantly more likely to report upper and lower respiratory symptoms. Given this overlap in respiratory complaints, it could be that CI may serve to amplify these traditional immune-related disorders and/or suggest that having asthma or hay fever could make one more vulnerable to CI.

Adolescent↗

PubMedDate not supplied

Relationship of normal serum vitamin B12 and folate levels to cognitive test performance in subtypes of geriatric major depression.

This retrospective study evaluated the relationships between normal serum vitamin B12 and folate levels and neuropsychologic measures in a sample of 60 geriatric inpatients with psychotic depression, nonpsychotic depression, bipolar disorder, and dementia--all consecutively referred for cognitive testing. The psychotic depression subgroup demonstrated numerous significant positive correlations between B12 and cognitive subtests not seen in other diagnostic subgroups, especially those of IQ, and verbal and visual memory. Metabolic factors including vitamin B12 may play specific roles in the cognitive dysfunctions of different geropsychiatric disorders.

Aged↗

PubMedDate not supplied

White paper: Neuropsychiatric aspects of sensitivity to low-level chemicals: a neural sensitization model.

The present paper summarizes the proposed time-dependent sensitization (TDS) and partial limbic kindling model for illness from low-level chemicals; reviews and critiques prior studies on CNS aspects of multiple chemical sensitivity (MCS); and outlines possible experimental approaches to future studies. TDS is the progressive and persistent amplification of behavioral, neurochemical, endocrine, and/or immunological responses to repeated intermittent stimuli over time. Partial limbic kindling is a progressive and persistent lowering of the threshold for eliciting electrical afterdischarges, but not motor seizures, in certain brain structures such as amygdala and hippocampus; behavioral consequences include increased avoidant behaviors. The focus of the paper is the controversial claim of altered sense of smell and illness from low levels of environmental chemicals (i.e., "cacosmia"), levels that should not have any biologically harmful effects by the rules of classical neurotoxicology. A major perspective of this paper is that the phenomenology of MCS is similar to that of time-dependent sensitization (reverse tolerance) and tolerance as studied in the substance abuse literature. The TDS model for MCS proposes that neurobiological amplification underlies the symptoms and phenomenology of these patients, including their behavioral features of heightened affective and somatic distress. It is hypothesized that MCS patients, who are mostly women, may be individuals who sensitize to substances rapidly and to the extreme, to the point of aversive symptomatology with less complete capacity for development of tolerance. Possible parallels between MCS and TDS include: (a) initiation by single or multiple intermittent stimuli; (b) lasting changes in subsequent reactivity to low levels of chemically unrelated substances; (c) cross-sensitization between the stressors and pharmacological agents; (d) greater vulnerability of individuals who are female, who have certain genetic characteristics, and/or who may be hyperreactive to novelty (cf. trait shyness); (e) lack of obvious differences between sensitized and unsensitized individuals at baseline without eliciting exposures; (f) bidirectionality (bipolarity) of sensitized responses; (g) both context-dependent (conditioned) and context-independent (unconditioned) amplification of responses. To minimize variability between studies, research in this area needs (a) consensus on a working case definition of MCS or at least of cacosmia as a specific symptom in a subset of well-defined medical and psychiatric disorders; and (b) proper design of chemical challenge studies in MCS, controlling for individual differences in sensitizability and for the properties of sensitization (e.g., repeated intermittent exposure tests) and tolerance (e.g., removal from customary ambient air exposures prior to testing).

Central Nervous System↗

PubMedDate not supplied

EEG responses to low-level chemicals in normals and cacosmics.

Recent studies from the University of Arizona indicate that normal subjects, both college students and the elderly, can register the presence of low-intensity odors in the electroencephalogram (EEG) in the absence of conscious awareness of the odors. The experimental paradigm involves subjects sniffing pairs of bottles, one containing an odorant (e.g. isoamyl acetate) dissolved in an odorless solvent (water or liquid silicone), the other containing just the solvent, while 19 channels of EEG are continuously recorded. For the low-intensity odor conditions, concentrations are adjusted downward (decreased) until subjects correctly identify the odor bottle at chance (50%). The order of odorants, concentrations, and hand holding the control bottle, are counterbalanced within and across subjects. Three previous experiments found that alpha activity (8-12 hz) decreased in midline and posterior regions when subjects sniffed the low-intensity odors. The most recent study suggests that decreased theta activity (4-8 hz) may reflect sensory registration and decreased alpha activity may reflect perceptual registration. In a just completed experiment involving college students who were selected based on combinations of high and low scores on a scale measuring cacosmia (chemical odor intolerance) and high and low scores on a scale measuring depression, cacosmic subjects (independent of depression) showed greater decreases in low-frequency alpha (8-10 hz) and greater increases in low-frequency beta (12-16 hz) to the solvent propylene glycol compared to an empty bottle. Topographic EEG mapping to low-intensity odorants may provide a useful tool for investigating possible increased sensitivity to specific chemicals in chemically sensitive individuals.

Adolescent↗