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Biomedical subjects

I R Bell

Publications and source records attributed to I R Bell.

At least 37 records · Page 2Linked to original sources
PubMed1996

Clinically relevant EEG studies and psychophysiological findings: possible neural mechanisms for multiple chemical sensitivity.

This paper addresses the evidence for the face, construct, and criterion-related validity of the olfactory-limbic/neural sensitization model for multiple chemical sensitivity (MCS). MCS is a poorly-understood, controversial condition in which low levels of environmental chemicals are reported to trigger disabling levels of illness in certain individuals. Neural sensitization processes could generate an endogenous amplification of responsivity to exogenous substances, thereby providing a plausible explanation for the apparent lack of a classical toxicological dose-response relationship in MCS. Convergent data from both survey and psychophysiological studies of MCS patients and of persons from the community without MCS, but who report elevated frequency of illness from chemical odors (cacosmics), support the involvement of the limbic system and the sensitizability of cacosmics, as predicted by the model. Recent studies show that cacosmics do sensitize their heart rate, blood pressure, and plasma beta-endorphin responses to repeated exposures to a novel laboratory procedure involving dietary manipulations over time. Cacosmia may represent a pathological form of neural plasticity. Taken together, the model and the available evidence suggest the need for more intensive investigation of MCS from the standpoint of possible neurobiological mechanisms affecting cognitive, emotional, and somatic functions.

Animals↗
PubMed1996

A polysomnographic study of sleep disturbance in community elderly with self-reported environmental chemical odor intolerance.

Subjective sleep complaints and food intolerances, especially to milk products, are frequent symptoms of individuals who also report intolerance for low-level odors of various environmental chemicals. The purpose of the present study was to evaluate the objective nature of nocturnal sleep patterns during different diets, using polysomnography in community older adults with self-reported illness from chemical odors. Those high in chemical odor intolerance (n = 15) exhibited significantly lower sleep efficiency (p = .005) and lower rapid-eye-movement (REM) sleep percent (p = .04), with a trend toward longer latency to REM sleep (p = .07), than did those low in chemical intolerance (n = 15), especially on dairy-containing as compared with nondairy (soy) diets. The arousal pattern of the chemical odor intolerant group differed from the polysomnographic features of major depression, classical organophosphate toxicity, and subjective insomnia without objective findings. The findings suggest that community elderly with moderate chemical odor intolerance and minimal sleep complaints exhibit objectively poorer sleep than do their normal peers. Individual differences in underlying brain function may help generate these observations. The data support the need for similar studies in clinical populations with chemical odor intolerance, such as multiple chemical sensitivity patients and perhaps certain veterans with "Persian Gulf Syndrome."

Aged↗
PubMed1996

Time-dependent sensitization of plasma beta-endorphin in community elderly with self-reported environmental chemical odor intolerance.

This study examined plasma beta-endorphin as a marker of the physiological stress response in community elderly who were either high (n = 15) or low (n = 15) in self-rated frequency of illness from environmental chemical odors. Individuals who report nonatopic multiple sensitivities to or intolerances for low levels of environmental chemicals also claim high rates of comorbid food sensitivities or intolerances. Subjects gave 9 AM blood samples for plasma beta-endorphin 90 min after ingesting either 1% fat cow's milk or a soy-based nondairy drink, on six different mornings in the laboratory after all-night sleep recordings. The six sessions-were divided into three sets of two successive days each, with each set [involving baseline (ad lib milk), nondairy (soy-based), and dairy diets] separated from the next by 3 weeks. In the chemically tolerant subjects, stably lower beta-endorphin levels suggested that milk may have been a physiologically less stressful beverage than was the soy drink. In contrast, the chemical odor intolerant group exhibited a) increased levels of plasma beta-endorphin averaged over the 6 days (p = .02); and b) marked fluctuations in endorphin from one laboratory day to the next (Group x Diet x Day interaction, p = .005). The findings were consistent with time-dependent, context-dependent sensitization of beta-endorphin in the chemical odor intolerant individuals.

Aged↗
PubMed1996

Neural sensitization and physiological markers in multiple chemical sensitivity.

This paper summarizes the key features of the olfactory-limbic, neural sensitization model for multiple chemical sensitivity (MCS) and presents relevant data on chemically intolerant human subjects from laboratory studies using quantitative electroencephalography, polysomnography, neuropsychological tests, cardiovascular measurements, and blood markers. MCS is a poorly understood chronic, polysymptomatic condition in which some prior controlled research studies have failed to find evidence to differentiate active from placebo tests. Closer examination of past MCS research, however, reveals that studies have failed to incorporate the design and methodological approaches necessary to test for nonimmunological sensitization. Time-dependent sensitization (TDS) is a well-documented phenomenon in the pharmacology literature involving the progressive increase in a given response by the passage of time between the initial and subsequent exposures to a substance or a stressor. As in MCS, multiple, chemically unrelated agents can trigger TDS. Females time-sensitize more readily than do males. Pharmacological and nonpharmacological (stress) stimuli can cross-sensitize. Dopaminergic pathways in the brain and the hypothalamic-pituitary-adrenal axis are likely involved in TDS. Data on the symptomatology of MCS point to central nervous system involvement, including limbic regions that receive input from both olfactory (odor) and trigeminal (irritant) pathways. Limbic and mesolimbic brain regions are among the most sensitizable to repeated, intermittent environmental stimuli. Sensitizable individuals can show no difference or lesser responses to a test substance on initial exposure, but later exhibit much greater increases in responsivity on the next exposure after a period of days. For future research, it is essential to distinguish chemical intolerance symptoms such as derealization, sudden mood changes, musculoskeletal pain, menstrual dysfunction, and uncontrollable sleepiness from chemical phobia and avoidance behaviors. This model permits hypothesis-driven research on MCS and has major implications for interpretation of apparently positive and negative tests for "true" as opposed to "perceived" sensitivity to low levels of environmental chemicals.

Humans↗
PubMed1996

Slowed reaction time performance on a divided attention task in elderly with environmental chemical odor intolerance.

Previous research has suggested an association between the subjective report of illness from environmental chemical odors and poorer cognitive task performance in persons with industrial levels of xenobiotic exposures. The present study investigated baseline morning performance on a computerized divided attention task in active retired adults without occupational exposures or clinical disorders who nonetheless rated themselves currently high versus low in episodic illness from the odor of certain environmental chemicals. The chemically intolerant group showed slower reaction times in registering both centrally and peripherally placed stimuli, but no difference in making target tracking errors. Measures of negative affect did not account for these findings. Taken together with evidence for heightened neurobehavioral sensitization in this population, the data suggest disturbances in allocation of attention and related cognitive functions.

Aged↗
PubMed1995

Increased limbic system symptomatology and sensitizability of young adults with chemical and noise sensitivities.

We previously hypothesized that individual differences in (a) limbic system reactivity and (b) central nervous system sensitizability underlie vulnerability to environmental stimuli, not only in the controversial clinical condition multiple chemical sensitivity (MCS), but also in the general population. Earlier research has shown overlaps in the characteristics of persons who report noise and air pollutant sensitivities. This study assessed questionnaire responses of 897 young adult college students who reported high versus low frequency of illness from several environmental chemical odors and concomitantly high versus low sensitivity to environmental noise. Subjects who reported increased rates of illness from chemical odors with or without noise sensitivity scored significantly higher (P < 0.0001) on a measure of limbic system symptomatology derived from ictal sensory, somatic, mnemonic, and behavioral manifestations of temporal lobe epilepsy. The group rating high both for illness from chemicals and for noise sensitivity had characteristics predictive of heightened sensitizability from the animal research on time-dependent sensitization (progressive response amplification to repeated, intermittent stimuli over time): i.e., higher female to male ratio (gender risk factor), increased rates of drug abuse problems in blood relatives (genetic risk factor), trait shyness (hyperreactivity to novelty), and increased carbohydrate craving. Despite the increased family histories of drug abuse and levels of personal anxiety and depression, the chemical- and noise-sensitive group reported the lowest rates of current smoking or personal drug abuse problems and the highest frequency of illness from drinking a small amount of alcohol. Taken together, the findings suggest that limbic system dysfunction associates more with chemical than with noise sensitivity; that individuals with both chemical and noise sensitivity may be the most sensitizable subset of the population for prospective studies, and that, in their substance use patterns, young adults with both chemical and noise sensitivity are more similar to MCS patients than are their peers with chemical or noise sensitivity alone.

Adolescent↗
PubMed1995

Trait shyness in the elderly: evidence for an association with Parkinson's disease in family members and biochemical correlates.

The emergence of potential treatments to slow the progression of idiopathic Parkinson's disease (PD) has increased the need for early identification of persons at risk. Although considered controversial, some prior studies indicate that PD patients may have premorbid histories of greater trait introversion or shyness as well as increased rates of disorders associated with shyness (e.g., anxiety, affective disorders, and irritable bowel syndrome). Essential features of trait shyness include (a) inhibited and avoidant behaviors and (b) physiological hyperreactivity to the novel or unfamiliar. In parallel, (a) depression in PD patients is associated with increased harm avoidance (a possible serotonergic function), and (b) PD patients have premorbid and comorbid decreases in novelty-seeking (a possible dopaminergic function). Taken together, previous research suggests the following hypotheses: (1) given evidence for marked heritability of shyness, shy elderly should report higher rates of PD in their family members than would nonshy elderly; and (2) shy elderly without PD should exhibit psychological and biologic characteristics similar to those reported in PD. Two groups, representing the top 27% (n = 37) and bottom 31% (n = 43) of scores on a standardized shyness scale, were drawn from a larger cohort of 138 older adults (ages 50-90) living in an active retirement community. Seventeen percent of the shy versus 2% of the nonshy reported PD in a family member or self (P < .05). Shy elderly were significantly more anxious (P < .01) and depressed (P < .05) than were the nonshy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Medical histories and psychological profiles of middle-aged women with and without self-reported illness from environmental chemicals.

BACKGROUND: Cacosmia, which is a predictor of cognitive deficits in industrial samples, is a core symptom of several controversial syndromes. Previous studies of cacosmic populations have considered only psychiatric but not medical or family histories of identified patients. METHOD: This questionnaire survey study examined subjective characteristics of illness from chemical odors, sensitivity to chemicals, psychological and stress profiles, and medical, psychiatric, and family health histories of 28 middle-aged women with cacosmia in self-reported poor health attributed to chemicals (MCS), 17 controls with cacosmia in good health, and 20 normal controls without cacosmia in good health. RESULTS: Those with MCS rated themselves in significantly poorer overall health with higher Pennebaker symptom scores, a larger number of chemical triggers, and greater frequency of illness from chemicals than the other two groups, even after controlling for variables on which the groups differed (i.e., education, Symptom Checklist-90 [revised] somatization, obsessive-compulsiveness, depression, anxiety, phobic anxiety, psychoticism, Barsky Somatic Symptom Amplification, and Cheek-Buss shyness). Despite increased levels of affective distress, those with MCS reported the greatest intolerance for alcohol and the lowest alcohol consumption. CONCLUSION: The data suggest that women with MCS report increased disability, multiple medical diagnoses including inflammatory and gynecologic dysfunctions, and psychological distress. The data are consistent descriptively with the phenomenology of somatization disorder. However, the persisting significance of group health rating differences after controlling for psychological variables, the lack of differences in life stress ratings between those with MCS and healthy cacosmics, the later age at onset (60% after age 30 years), and the lack of excess family psychiatric histories in this sample of women with MCS suggest a potential role for an organic factor in the evolution of poor health in certain cacosmics.

Adult↗
PubMed1994

Sensitization to early life stress and response to chemical odors in older adults.

This study examined the hypothesis that older persons who currently report illness from environmental chemical odors (cacosmia) may have experienced higher levels of stress early in life than did noncacosmic controls. The hypothesis derives from a time-dependent sensitization (TDS) model for cacosmia (Bell et al 1992) that predicts a relative interchangeability of stress and chemicals in inducing and eliciting sensitized responses in vulnerable individuals. Subjects were selected from those in the top 24% (cacosmic) and bottom 27% (noncacosmic) of a sample of 192 older adults (mean age 73.8 years) for self-reported frequency of illness form the odors of pesticide, car exhaust, paint, perfume, and new carpet. As in previous investigations, cacosmics were younger, more depressed, and more shy; cacosmics also included a higher proportion of women (83% versus 61%). As predicted, cacosmics rated themselves higher in stress for the first four decades of their lives, but not the recent past or present, even after controlling for depression, anxiety, hostility, shyness, age, and gender. Cacosmics reported increased prevalence of physician-diagnosed nasal allergies, breast cysts, hypothyroidism, sinusitis, food sensitivities, irritable bowel, and migraine headache. Only 4% of the overall sample (including 9% of the cacosmics) acknowledged the controversial physician diagnosis of "chemical sensitivity." The replicated observation of greater shyness in cacosmics is consistent with the ability of hyperreactivity to novelty to predict enhanced susceptibility to TDS from low levels of pharmacological agents in animals. The findings support a TDS model for cacosmia and suggest that cacosmia as a symptom identifies a large subset of the nonindustrial population with significant psychophysiological health problems that merit further objective examination.

Aged↗
PubMed1994

Psychological characteristics and subjective intolerance for xenobiotic agents of normal young adults with trait shyness and defensiveness. A parkinsonian-like personality type?

The present study examines the psychological characteristics and self-reported responses to xenobiotic agents such as tobacco smoke and pesticide of normal young adults with personality traits similar to those claimed for Parkinsonian patients. Previous research, though controversial, has suggested that persons with idiopathic Parkinson's disease (PD) have premorbid personality traits that may include shyness and repressive defensiveness. Other epidemiological evidence indicates that PD patients may have premorbidly increased prevalence of anxiety, affective, and/or somatoform disorders; decreased rates of smoking and alcohol consumption; and elevated exposure to herbicides or pesticides. A total of 783 college students enrolled in an introductory psychology course completed the Cheek-Buss Scale (shyness), the Marlowe-Crowne Social Desirability Scale (defensiveness), Symptom Checklist 90 (revised), the Mastery Scale, a health history checklist, and rating scales for frequency of illness from alcohol and 10 common environmental chemicals. Subjects were divided into four groups on the basis of above- versus below-median scores on the Cheek-Buss and Marlowe-Crowne scales (persons high in shyness and defensiveness, those high only in shyness, those high only in defensiveness, and those low in both shyness and defensiveness). The group high in shyness but low in defensiveness had the highest, whereas the group low in shyness but high in defensiveness had the lowest, total scores on the SCL-90-R; the two shyest groups were lowest in sense of mastery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Vascular disease risk factors, urinary free cortisol, and health histories in older adults: shyness and gender interactions.

We studied relationships between shyness and health during a health screening survey of older adults (ages 50-88) living in an active retirement community in the southwestern United States (n = 232). As in previous studies of infants, older individuals with hay fever, insomnia and constipation were more shy than those without these problems. Shy persons overall showed higher sitting systolic blood pressure and a larger fall in orthostatic systolic blood pressure on standing; shy men had a greater prevalence of hypertension histories than did low-shy men. Shy subjects of both sexes had lower HDL cholesterol and higher triglycerides than did low-shy subjects; shy women tended to have higher LDL cholesterol than did low-shy women. In contrast with findings of elevated salivary cortisol in extremely inhibited children of both sexes, only shy women had higher 24 h urinary free cortisol excretion than did low-shy women; men showed the opposite pattern, possibly related to suppression of aggression. Shy men also tended to report a higher prevalence of thyroid disease history than did low-shy men (20% versus 6%). Notably, autoimmune thyroiditis has previously been linked with panic and depression, disorders which in turn have been associated with shyness. Taken together with previous work in shy children and their families, the data raise the possibility of (a) increased risk for arteriosclerotic vascular disease; and (b) increased risk of adrenal- and/or thyroid-related diseases in certain shy older adults.

Aged↗
PubMed1993

Polysymptomatic syndromes and autonomic reactivity to nonfood stressors in individuals with self-reported adverse food reactions.

This study compared symptom reports and cardiovascular reactivity of a group of 24 individuals recruited from the community who reported a cognitive or emotional symptom caused by at least one food (food-sensitivity reporters, FSR) vs those of 15 controls (C) without a history of food, chemical, drug, or inhalant sensitivities. The main findings were: 1) FSR indicated sensitivities not only to foods, but also to environmental chemicals, drugs, and natural inhalants, as well as significantly more symptoms than C in multiple systems; 2) more FSR than C noted recent state depression and anxiety, as well as higher trait anxiety on the Bendig form of the Taylor Manifest Anxiety Scale; 3) however, on multiple regression analysis, not only depression, but also the number of sensitivities (foods, chemicals, drugs, inhalants), accounted for part of the variance in total number of symptoms (38 and 17%, respectively), whereas none of the affective measures accounted for any of the variance in total number of sensitivities over all subjects; 4) after controlling for depression and anxiety, FSR still showed a trend toward poorer performance on a timed mental arithmetic task (p = 0.16); and 5) FSR and C showed opposite patterns of heart rate change to two different stressful tasks (mental arithmetic and isometric exercise) (group by task interaction, p < 0.05). The data are discussed in terms of a time-dependent sensitization (TDS) process that predicts a cross-sensitizing and cross-reactive role for xenobiotic agents (e.g., foods, chemicals, drugs, and inhalants) and for salient psychological stress in the expression of psychophysiological dysfunctions of FSR. As in other chronically ill populations, negative affect in food-sensitive individuals may explain greater symptom reporting, but not necessarily account for the illness itself. For either a food or a psychological stimulus to begin to elicit sensitized responses, e.g., marked physiological differences from C, FSR may require multiple, intermittent exposures spaced over 5-28 days rather than on only 1 day.

Adult↗
PubMed1993

Symptom and personality profiles of young adults from a college student population with self-reported illness from foods and chemicals.

Despite much debate over a presumptively somatic vs psychological etiology of nonatopic food and chemical sensitivities, little systematic research has addressed the issues. The present study investigated self-reported illness from several common foods (wheat, dairy, eggs) and chemicals (pesticide, car exhaust, paint, perfume, new carpet), symptom patterns, and psychological profiles of a sample of young adult college students (n = 490, age 19.4 +/- 2.4, 52% female/48% male). Subjects were divided into 4 groups on the basis of sample medians for frequency of illness from the foods (FI) and chemicals (CI); high FI with high CI (FI/CI), high FI alone, high CI alone, and NOILL (low FI and CI). FI was associated with more defensiveness (denial of negativity) while CI was linked with more shyness (avoidance of novelty). Women outnumbered men in all groups (FI/CI: 61%; FI: 80% CI: 55%) except the NOILL (40% women). Nevertheless, the FI/CI, FI, and/or CI groups still had significantly higher total symptom scores as well as more indigestion, headache, and memory trouble than did the NOILL group, even after depression, anxiety, shyness, defensiveness, and gender were covaried. The illness groups reported significantly more limitation of foods that mobilize endogenous opioids or generate exogenous opioids (sweets, fats, bread) as well as more illness from opiate drugs, small amounts of beverage alcohol, and late meals. Nasal symptoms from pollens or animals were more common in the FI/CI (42%) and CI (42%) than in FI (26%) or NOILL (28%) groups. Premenstrual tension syndrome and irritable bowel were also more common in the FI/CI group. The findings indicate that young adults outside the clinical setting who are relatively higher in FI and/or CI have distinctive symptom and psychological patterns. Covariate analyses suggest that important symptoms in FI and CI individuals such as indigestion, headache, and memory problems may occur in addition to rather than as simply part of emotional distress. The data are consistent with a previously hypothesized role of olfactory-limbic and hypothalamic pathways and with a time-dependent sensitization model for illness from foods and chemicals.

Adolescent↗
PubMed1992

An olfactory-limbic model of multiple chemical sensitivity syndrome: possible relationships to kindling and affective spectrum disorders.

This paper reviews the clinical and experimental literature on patients with multiple adverse responses to chemicals (Multiple Chemical Sensitivity Syndrome-MCS) and develops a model for MCS based on olfactory-limbic system dysfunction that overlaps in part with Post's kindling model for affective disorders. MCS encompasses a broad range of chronic polysymptomatic conditions and complaints whose triggers are reported to include low levels of common indoor and outdoor environmental chemicals, such as pesticides and solvents. Other investigators have found evidence of increased prevalence of depression, anxiety, and somatization disorders in MCS patients and have concluded that their psychiatric conditions account for the clinical picture. However, none of these studies has presented any data on the effects of chemicals on symptoms or on objective measures of nervous system function. Synthesis of the MCS literature with large bodies of research in neurotoxicology, occupational medicine, and biological psychiatry, suggests that the phenomenology of MCS patients overlaps that of affective spectrum disorders and that both involve dysfunction of the limbic pathways. Animal studies demonstrate that intermittent repeated low level environmental chemical exposures, including pesticides, cause limbic kindling. Kindling (full or partial) is one central nervous system mechanism that could amplify reactivity to low levels of inhaled and ingested chemicals and initiate persistent affective, cognitive, and somatic symptomatology in both occupational and nonoccupational settings. As in animal studies, inescapable and novel stressors could cross-sensitize with chemical exposures in some individuals to generate adverse responses on a neurochemical basis. The olfactory-limbic model raises testable neurobiological hypotheses that could increase understanding of the multifactorial etiology of MCS and of certain overlapping affective spectrum disorders.

Air Pollutants↗
PubMed1992

Plasma homocysteine in vascular disease and in nonvascular dementia of depressed elderly people.

Depression among elderly people with reversible cognitive loss often manifests with concomitant vascular disease and can also precede the development of nonvascular degenerative dementia. Little is known about etiological factors for reversible or irreversible dementias in older depressed people. The amino acid homocysteine (HC), which is both a vascular disease risk factor and a precursor of the excitotoxic amino acids cysteine and homocysteic acid, could play a role in the pathophysiology of such individuals. Twenty-seven depressed elderly acute inpatients by DSM-III-R criteria had significantly higher plasma homocysteine levels and lower cognitive screening test scores than did 15 depressed young adult inpatients. HC was highest in the older patients who had concomitant vascular diseases (n = 14). HC was lowest in the older depressives who had neither vascular illnesses nor dementia (n = 8), comparable to the young adult depressives. Higher HC correlated significantly with poorer cognition only in the nonvascular geriatric patients (rs = -0.53). The findings extend earlier work showing higher HC in vascular patients from general medical populations, and also suggest a possible metabolic factor in certain dementias associated with late-life depression.

Adult↗
PubMed1992

Low thyroxine levels in female psychiatric inpatients with riboflavin deficiency: implications for folate-dependent methylation.

Intermediates in the folate-dependent methylation pathways may play a role in the etiology and treatment of such mental disorders as major depression. These pathways include a step dependent on a riboflavin (B2)-derived coenzyme, flavin adenine dinucleotide (FAD), which is reportedly sensitive to thyroid status and to phenothiazine and tricyclic drug exposure. In a sample of 52 male and female acute psychiatric inpatients, 17% (n = 9) showed B2 deficiency (i.e., insufficient FAD activity) on a functional red blood cell enzyme assay, but only one B2-deficient individual showed deficiency in another B-complex vitamin (folate). All patients with B2 deficiency were women, who were also significantly younger than the rest of the sample. The B2-deficient women had significantly lower thyroxine levels, even when controlling for sex and covarying for age. B2-deficient patients exhibited a nonsignificant trend toward more unipolar depression (44% vs 14%), but not toward bipolar or schizophrenic disorders. As in a previous study, drug exposure did not show a relationship to riboflavin deficiency in this sample. The findings suggest that B2 (FAD) activity may serve as a sensitive marker of thyroxine status in certain female psychiatric inpatients and that B2 deficiency may play an etiological role in defects of the methylation pathways in a subset of mentally ill individuals.

Adult↗