Biomedical subjects

P Mitchell

Publications and source records attributed to P Mitchell.

At least 289 records · Page 16Linked to original sources

PubMed1997

Hormone replacement therapy, reproductive factors, and cataract. The Blue Mountains Eye Study.

The relation between estrogen (endogenous and exogenous) and cataract is unclear, with one large population-based study recently suggesting a protective effect of estrogen replacement therapy. The study reported in this paper, the Blue Mountains Eye Study, was conducted in Australia in 1992-1993 and involved 2,072 women aged 49-97 years. Subjects were recruited from a defined geographic area; the participation rate was 83 percent. Eye examination included photographs of the lens, which were graded for presence and severity of cortical, nuclear, and posterior subcapsular cataracts. Later age at menarche was associated with increased prevalence of all three types of cataract, but there were no associations with age at menopause, number of children, or use of the oral contraceptive pill. Among all women, there was no association between hormone replacement therapy and cataract. However, current users of hormone replacement therapy aged 65 years and over, among whom the duration of use was likely to have been longer than in younger current users, had lower prevalence of cortical cataract than did never users; the odds ratio adjusted for numerous potential confounders was 0.4 (95 percent confidence interval 0.2-0.8). The prevalence of posterior subcapsular cataract was increased in current users of hormone replacement therapy who had had a nonsurgical menopause; the adjusted odds ratio was 2.1 (95 percent confidence interval 1.1-4.1). The results of this study support the hypothesis that estrogen and/or progestin may be involved in cataract development. The effect of hormone replacement therapy on the lens needs to be evaluated in the laboratory and in further observational epidemiologic studies.

Aged↗

PubMed1997

Visual impairment in nursing home residents: the Blue Mountains Eye Study.

OBJECTIVES: To assess the prevalence and causes of visual impairment, and the proportion of treatable eye conditions, among nursing home residents. DESIGN AND SETTING: The Blue Mountains Eye Study is a population-based survey of vision and common eye diseases in people aged 50 or older in two postcode areas west of Sydney. Nursing home examinations were conducted during 1993. PARTICIPANTS: Three representative nursing homes were selected from the nine in the study area. There were 128 residents aged 50 or older (64% females), representing 21% of all eligible nursing home residents in the two postcode areas. MAIN OUTCOME MEASURE: Blindness or visual impairment in one or both eyes. RESULTS: Eye examinations were refused by five nursing home residents, and dementia precluded eye examination in 34 (28%) of the remainder. We found significantly higher prevalences (fivefold increase) of bilateral (11%) and unilateral (21%) blindness in nursing home residents compared with local community residents (bilateral, 0.5%; unilateral, 2%). In seven of the 10 blind nursing home residents, the blindness was potentially reversible (advanced cataract); late age-related macular degeneration (AMD) was the second most frequent cause of blindness, affecting one or both eyes of 12% of residents. Open-angle glaucoma affected 10% and advanced cataract 11%; a history of past cataract surgery was obtained in 14%. CONCLUSIONS: These data confirm earlier reports of a substantial number of treatable eye diseases, particularly advanced cataract, in nursing home residents, and indicate a need for increased surveillance of these communities. The high rate of visual impairment and blindness, compared with similar age groups in the local community, suggests that visual disability may contribute to nursing home placement.

Age Distribution↗

PubMed1997

Alcohol, smoking, and cataracts: the Blue Mountains Eye Study.

OBJECTIVE: To investigate the associations between alcohol consumption, tobacco smoking, and cataract. DESIGN: A population-based, cross-sectional study. SETTING: An urban community in the Blue Mountains, close to Sydney, Australia. PARTICIPANTS: Three thousand six hundred fifty-four people aged 49 to 97 years. The participation rate was 82%. MAIN OUTCOME MEASURES: Smoking history and details of current alcohol consumption were assessed by questionnaire. Lens photographs were taken and graded for presence and severity of cortical, nuclear, and posterior subcapsular cataracts. RESULTS: After adjusting for multiple potential confounders, people who had ever smoked cigarettes had a higher prevalence than nonsmokers of more severe nuclear (adjusted odds ratio [OR], 1.3; 95% confidence interval [CI], 1.1-1.6) and posterior subcapsular (adjusted OR, 1.5; 95% CI, 1.1-2.1) cataracts. The association between pipe smoking and nuclear cataract (adjusted OR, 3.1; 95% CI, 1.5-8.2) was stronger than the association with cigarette smoking. Alcohol consumption was associated with a reduced prevalence of cortical cataract: compared with people who did not drink, the adjusted OR for cortical cataract among people who drank at least 1 drink a day was 0.7 (95% CI, 0.6-0.9). Heavy alcohol consumption (> or =4 drinks a day) was associated with nuclear cataract in current smokers (adjusted OR compared with nondrinkers, 3.9; 95% CI, 0.9-16.6) but not in never smokers. CONCLUSIONS: Consistent with other studies, smoking was associated with a higher prevalence of nuclear and posterior subcapsular cataracts. The only adverse effect of alcohol was among smokers: people who smoked and drank heavily had an increased prevalence of nuclear cataract.

Aged↗

PubMed1997

When speech conflicts with seeing: young children's understanding of informational priority.

In a series of investigations we found that children between 3 and 5 years of age judged that an utterance (such as, "There's milk in the jug") would be ignored by a listener who had previously seen something contradictory (orange juice in the jug). However, children judged that the listener would believe the message "There's milk in the jug" when he had not previously seen inside. In these various conditions, child participants had not seen for themselves what was inside the jug, so it was impossible for their own directly perceived knowledge to contaminate their judgments of what the protagonist believed. Under these conditions, even many false-belief failers did not assume that the listener would believe whatever they themselves thought was true. Moreover, the results of control conditions suggested that children's success could not be attributed to low-level strategies. These results seem to indicate an early understanding of how people prioritize information, with the consequence that they acknowledge that one and the same message would be believed in one context but not in another.

Child, Preschool↗

PubMed1997

Association of pseudoexfoliation syndrome with increased vascular risk.

PURPOSE: To examine vascular associations with pseudoexfoliation syndrome in view of the wide-spread elastosis now demonstrated in this disorder that affects many tissues, including vessel walls. METHODS: The Blue Mountains Eye Study is a population-based study of eye disease in an area west of Sydney, Australia. Of 4433 eligible persons aged 49 years or older, 3,654 (82.4%) participated. Signs of pseudoexfoliation were graded clinically, after excluding 108 people who had bilateral cataract surgery. RESULTS: Pseudoexfoliation was present in 81 (2.3%) of 3546 participants aged 49 years or older. The prevalence of pseudoexfoliation increased with age and was higher in women and in people with glaucoma. Pseudoexfoliation was statistically significantly associated with a history of angina or hypertension or a combined history of angina, acute myocardial infarction, or stroke. CONCLUSION: Slit-lamp signs of pseudoexfoliation may identify individuals with an increased vascular risk.

Aged↗

PubMed1997

Serum beta carotene, alpha tocopherol, and age-related maculopathy: the Blue Mountains Eye Study.

PURPOSE: To assess associations between serum beta carotene, alpha tocopherol, and age-related maculopathy. METHODS: We studied 156 subjects with age-related maculopathy matched for age, sex, and month of blood collection to 156 control subjects without age-related maculopathy. Subjects were identified from the Blue Mountains Eye Study: those with late age-related macular degeneration and early age-related maculopathy using examination and grading of retinal photographs, and control subjects without age-related maculopathy randomly sampled from the study population. RESULT: Neither serum alpha tocopherol nor beta carotene was significantly associated with age-related maculopathy. CONCLUSION: These findings provide no evidence of a protective association between serum alpha tocopherol or beta carotene and age-related maculopathy.

Australia↗

PubMed1997

Is there an association between migraine headache and open-angle glaucoma? Findings from the Blue Mountains Eye Study.

OBJECTIVE: To determine whether an association exists between migraine headache history and open-angle glaucoma (OAG). DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Subjects were 3654 people aged 49 or older; 82% of permanent residents from an area west of Sydney participated. INTERVENTION: All participants underwent an interview and a detailed eye examination, including automated perimetry and stereo optic disc photography. MAIN OUTCOME MEASURES: Open-angle glaucoma was diagnosed in subjects with matching typical glaucomatous visual field defects and pathologic optic disc cupping, independent of intraocular pressure level. The diagnosis of migraine history (typical or nontypical) was based on participant responses to specific questions, consistent with International Headache Society criteria. RESULTS: Open-angle glaucoma prevalence increased exponentially with age, with rates of 0.4%, 1.3%, 4.7%, and 11.4% among persons aged less than 60 years, between 60 and 69 years, between 70 and 79 years, and 80 years or older, respectively. The frequency of reporting a past history of typical migraine headache declined with increasing age, with rates of 23.1%, 16.2%, 12.8%, and 10.4% for corresponding age groups. For all age groups combined, there was no significant association between typical migraine headache and OAG (odds ratio [OR], 1.3; 95% confidence interval [CI], 0.8-2.2), after multivariate adjustment. However, after stratifying into 10-year age groups, increased odds for OAG were found for people giving a history of typical migraine headache and aged 70-79 years (OR, 2.5; 95% CI 1.2-5.2), after adjusting for variables found associated with glaucoma. This association was marginally stronger for high-pressure OAG cases (OR, 2.7; 95% CI, 1.1-5.6). CONCLUSIONS: These data suggest the possibility of an association between history of typical migraine headache and OAG, which could be modified by age.

Aged↗

PubMed1997

Prevalence and associations of epiretinal membranes. The Blue Mountains Eye Study, Australia.

PURPOSE: The purpose of the study is to determine the prevalence and associations of epiretinal membranes in a defined older Australian population and to assess their influence on visual acuity. METHODS: Three thousand six hundred fifty-four persons 49 years of age or older, representing 88% of permanent residents from an area west of Sydney, underwent a detailed eye examination, including stereo retinal photography. Epiretinal membranes were diagnosed clinically and from photographic grading. RESULTS: Signs of epiretinal membranes were found in 243 participants (7%; 95% confidence interval [CI], 6.1, 7.6), bilateral in 31%. The prevalence was 1.9% in persons younger than 60 years of age, 7.2% in persons 60 to 69 years of age, 11.6% in persons 70 to 79 years of age, and 9.3% in persons 80 years of age and older, with slightly higher rates in women. Two stages were identified: an early form without retinal folds, termed "cellophane macular reflex" present in 4.8%, and a later stage with retinal folds, termed "preretinal macular fibrosis" (PMF), found in 2.2% of the population. Preretinal macular fibrosis, but not cellophane macular reflex, had a small, significant effect on visual acuity. Preretinal macular fibrosis was significantly associated with diabetes, after age-gender adjustment, in subjects without signs of diabetic retinopathy (odds ratio, 3.2; 95% CI, 1.4, 7.2). Preretinal macular fibrosis also was associated with increased fasting plasma glucose (odds ratio, 1.2; 95% CI, 1.1, 1.3). Epiretinal membranes were found in 16.8% of persons who had undergone cataract surgery in one or both eyes (including PMF in 3.7%), in 16.1% of retinal vein occlusion cases (PMF in 12.5%), both significantly higher rates than in subjects without these conditions (P < 0.0001), and in 11% of persons with diabetic retinopathy (PMF in 3.6%), not significantly higher (P = 0.17). CONCLUSIONS: This study has documented the frequency and mild effect on vision of epiretinal membranes in an older population. Diabetes was associated significantly with idiopathic cases, whereas well-known associations with past cataract surgery and retinal disease were confirmed.

Adult↗

PubMed1997

Sun exposure and age-related macular degeneration. An Australian case-control study.

BACKGROUND: The notion that sun exposure is a risk factor for age-related macular degeneration (AMD) is widespread, but studies have not shown this conclusively. METHODS: To test the hypothesis that AMD cases have greater ocular sun exposure than control subjects, the authors compared 409 cases with 286 control subjects resident in Newcastle, Australia. Sensitivity to sun and glare of the participants was characterized. Sun exposure was estimated from detailed histories and was validated against sun-seeking or avoidance behavior expected, given sun sensitivity and history of treatment for skin neoplasia. RESULTS: Contrary to the authors' hypothesis, control subjects had greater median annual ocular sun exposure (865 hours) than cases (723 hours), Mann-Whitney U (U) = 45704, z = -4.9, P > 0.0001. Cases had poorer tanning than did control subjects (mean 2 = 18.2, 4 df, P = 0.001) and as young adults were more sensitive to glare, odds ratio (OR), 2.5; 95% confidence intervals (CIs), 1.8 to 3.5. After stratifying by tanning ability, in the poor-tanning group, the median annual sun exposure of control subjects (685 hours) exceeded that of cases (619 hours), U = 6556, z = -1.9, P = 0.06. Among people who tanned well, control subjects also had significantly greater annual sun exposure than did cases (940 vs. 770 hours), U = 16263, z = -3.7, P = 0.0002. CONCLUSIONS: Sensitivity to glare and poor tanning ability are markers of increased AMD risk. Sun sensitivity confounds study of the postulated AMD-sunlight link. Despite analyses stratified by sun sensitivity, sun exposure was greater in control subjects than in cases with AMD.

Adult↗

PubMed1997

Open-angle glaucoma and diabetes: the Blue Mountains eye study, Australia.

PURPOSE: The authors explore the relationship between diabetes and open-angle glaucoma in a defined older Australian population. METHODS: Three thousand six hundred fifty-four people 49 to 96 years of age, living west of Sydney, underwent a detailed eye examination. This included automated perimetry, stereo optic disc photographs, and applanation tonometry; in addition, fasting plasma glucose levels were ascertained. Glaucoma was diagnosed if matching visual field and optic disc cupping were present, without reference to intraocular pressure (IOP) level. Ocular hypertension (OH) was diagnosed if IOP in either eye was > or = 22 mm and glaucomatous disc and visual field changes were absent. RESULTS: Glaucoma prevalence was increased in people with diabetes, diagnosed from history or elevated fasting plasma glucose level (5.5%), compared with those without diabetes (2.8%; age-gender adjusted odds ratio [OR] 2.12, 95% confidence intervals [CI] 1.18-3.79). Ocular hypertension was also more common in people with diabetes (6.7%), compared with those without diabetes (3.5%; OR 1.86, CI 1.09-3.20). Diabetes was present in 13.0% of people with glaucoma, compared with 6.9% of those without glaucoma. This increase was highest for previously diagnosed glaucoma cases (16.7%; OR 2.82, CI 1.35-5.87). However, in 67% of such cases, glaucoma was diagnosed before the diabetes. For those not receiving glaucoma treatment, IOP was consistently slightly higher in people with diabetes, with the age-gender adjusted mean IOP 0.6 mm higher. CONCLUSIONS: The significant and consistent association between diabetes and glaucoma found in our study, which appeared independent of the effect of diabetes on IOP, suggests that there is a real association between these two diseases.

Aged↗

PubMed1997

Prevalence of cataract in Australia: the Blue Mountains eye study.

PURPOSE: The authors determined the age and gender-specific prevalence of nuclear, cortical, and posterior subcapsular cataract (PSC) in a representative sample of older Australians. METHODS: As part of a population-based study of eye disease in the Blue Mountains, west of Sydney, 3654 people aged 49 to 96 years underwent a detailed eye examination, including lens photography (slit-lamp and retroillumination). The photographs were assessed by masked graders using the Wisconsin Cataract Grading System, with acceptable reproducibility. RESULTS: Past cataract surgery had been performed in either eye of 6.0% and in both eyes of 2.9% of participants in this study, equally in men and women. Moderate or advanced nuclear opacities were present in 53.3% of women and 49.7% of men. Moderate cortical cataract was present in 25.9% of women and 21.1% of men. Posterior subcapsular cataract was less frequent, found in 6.2% of women and 6.5% of men. After adjusting for age, these gender differences were statistically significant only for cortical cataract. The age-specific prevalence rates found for early and late cataract or for past cataract surgery are very similar to rates reported in the Beaver Dam Eye Study (BDES), Wisconsin, using the same definitions. Comparison of age-specific rates for each cataract type indicated lower rates for nuclear cataract, slightly lower rates for PSC and slightly higher rates for cortical cataract compared with the BDES. However, the rates for nuclear cataract were the only statistically significant differences between the two studies. Previously described susceptibility of the lower nasal lens to cortical cataract was confirmed, supporting a potential role of sunlight exposure in its development. CONCLUSIONS: The Wisconsin cataract grading system was used in an older Australian population with acceptable reproducibility. The Blue Mountains Eye Study found similar age-specific prevalence rates for most of the types and stages of cataract compared with the BDES.

Aged↗

PubMed1997

Plumbing the depths: some problems in quantifying depression severity.

We first report further studies of the psychometric properties of the AUSSI), a brief (11-item) self-report depression measure assessing mood state severity and disability in a sample of 270 subjects. Total scores (combining mood state and disability) correlated well with another self-report measure of depression severity, the Beck, but minimally with both Hamilton and DSM-III-R Global Assessment of Function (GAF) scores. For a sub-sample where we had complete data sets (including a corroborative witness [CW] form of the AUSSI), we established moderate levels of agreement between self-report and CW AUSSI scores, important in supporting validity of its disability sub-scale. Against expectation, neither mood nor disability AUSSI scale scores differed across clinically meaningful depressive sub-types, while differentiation was demonstrated for the Hamilton and GAF measures. Differentiation for the Hamilton measure was clearly driven by several type-specific component clinical features, but also presumably contributed to by the clinician-rater format. Our study raises questions about the varying reference bases and semantics used by patients, corroborative witnesses and clinicians in rating depression severity, and which may generate similar or contrasting severity estimates across varying depressive sub-types.

Adolescent↗

PubMed1997

Distinguishing psychotic depression from melancholia.

We contrast 25 patients with "psychotic depression" (PD) against two age- and sex-matched groups of melancholic depressed patients. In terms of clinical features, specificity of PD was suggested for several features, including delusions, morbid cognitions (involving guilt and a sense of deserving punishment), hallucinations and constipation. In addition, the PDs had significantly higher levels of behaviourally rated psychomotor disturbance. A comprehensive list of risk factors to depression (e.g., socio-demographic, family history, parental influences, medical disorders, anxiety, stressors and personality style) were examined, without clear differentiation between the comparison groups apart from the suggestion that being a "worrier" and having tenuous stability under stress was over-represented in the PDs. Findings favour the view that psychotic depression is a sub-type of melancholic depression (accounting for the similar expression of the majority of clinical and possible aetiological variables across our contrasted "types'). Findings also suggest possible benefits from future phenomenological studies of psychotic depression relying more on observer-based rather than self-report or symptom data sets. Aetiological studies would benefit from focussing on those features identified as distinguishing the condition from melancholic depression.

Adult↗

PubMed1997

The effect of decreased catecholamine transmission on ERP indices of selective attention.

This study examines the effect of decreased catecholamine transmission on event-related potential (ERP) indices of selective attention. Intravenous clonidine (1.5 micrograms/kg Catapres), droperidol (15 micrograms/kg Droleptan), or placebo were administered to healthy adult males prior to performance of a multidimensional auditory selective attention task (SAT) in which dichotically presented sequences of tone pips varied on dimensions of location (left or right ear), pitch (high or low), and duration (short or long). Subjects were required to make a button press response to infrequent "target" stimuli that matched a prespecified stimulus on the three dimensions. ERPs were recorded during the task. Clonidine led to a significant increase of processing negativity (PN) over 200-400 ms at the irrelevant location. Droperidol led to a significant increase in reaction time (RT), a significant decrease in hit rate, and an attenuation of PN over the 200- to 400-ms and 400- to 700-ms epochs. Neither substance led to a significant change in P3 amplitude. The role of catecholamines in the selective attention subprocesses of "tuning" and "switching" is discussed.

Adrenergic alpha-Agonists↗

PubMed1997

How distinct is 'distinct quality' of mood?

BACKGROUND: The DSM-IV criteria for melancholia include the clinical feature 'distinct quality', defined as a mood state differing from that experienced in bereavement. Both propositions-its specificity to melancholia and its definition- remain problematical. METHODS: We examine both propositions by analysing an adjective checklist completed by melancholic and non-melancholic depressed subjects, as well as by a bereaved sample. The checklist was refined by a principal components analysis to four scales-one assessing a general 'mood' severity or dysphoric dimension, and the other three assessing dimensions of 'fatigue', 'numbness' and 'guilt'. RESULTS: If the concept of "distinct quality' has validity, we would require specificity of the refined qualitative constructs to melancholic depression. The 'numbness' component met that requirement, but only to a degree. While bereaved subjects did differ from those with melancholic depression on a number of our refined qualitative mood domains, such differences appeared more related to lower levels of depression in the bereaved sample. CONCLUSIONS: We argue for deleting the 'distinct quality' criterion from diagnostic checklists of melancholia until its definition has been improved, its utility demonstrated and its specificity to any depressive subtype established as having clinical significance.

Adult↗

PubMed1997

Increased rate of psychosis and psychomotor change in depression with age.

BACKGROUND: We examined the phenomenology of depression in younger (< 60 years old) versus older (> or = 60 years) subjects and, more specifically, the interaction between age and psychomotor disturbance associated with depression. METHOD: Two hundred and eighty-five patients with a DSM-III-R diagnosis of unipolar major depression referred to a mood disorders unit were assessed using the CORE rating scale, a sign-based system for defining melancholia. Subjects were also assessed using the Hamilton Rating Scale for Depression, Zung Depression Scale, Newcastle Endogenous Depression Inventory and the General Health Questionnaire. RESULTS: The total CORE score (and each of its subscales) was found to interact with age. Rates of psychotic and melancholic depression increased with age. Elderly depressives suffered more severe depression (higher HRSD scores), appetite loss and weight loss. Level of psychomotor disturbance and rates of psychosis did not differ between those elderly subjects with an early onset (before the age of 60 years) and those with a late onset (at or after 60 years) of depression. CONCLUSIONS: There appear to be robust phenomenological differences in depression between older and younger subjects. The association between age and psychomotor change may assist our understanding of the neurobiology of depression.

Adult↗

PubMed1997

The development of a refined measure of dysfunctional parenting and assessment of its relevance in patients with affective disorders.

BACKGROUND: The Parental Bonding Instrument (PBI) measures fundamental parenting dimensions (care and over-protection), but does not directly assess abusive parenting. METHODS: We describe the development of the Measure of Parenting Style (the MOPS), comprising refined PBI scales assessing parental indifference and over-control, as well as a scale assessing parental abuse. RESULTS: We examine psychometric properties of the MOPS, while several analyses build to the concurrent validity of the abuse scale as an experimental measure. We examine the extent to which both the PBI and the MOPS scales showed specificity of dysfunctional parenting to the non-melancholic depressive subtype, and across a range of anxiety disorders. Non-melancholic depressed patients returned anomalous parenting scale scores (compared to melancholic subjects), but only when such subtyping decisions were clinician-generated. Those receiving DSM-III-R lifetime anxiety diagnoses of panic disorder and of social phobia returned higher PBI protection and MOPS over-control scores than non-anxious subjects, while differences were not established for those with generalized anxiety disorder or obsessive compulsive disorder. CONCLUSIONS: We consider the likely utility of the MOPS scale and note the module capacity of separate MOPS and PBI scales, which allow a set of options for assessing perceived parenting characteristics.

Adolescent↗

PubMed1997

Embolization of carotid cavernous fistulas via the superior ophthalmic vein.

BACKGROUND: Carotid cavernous fistulae are treatable by various means, one of which is embolization via the superior ophthalmic vein (SOV). The use of this technique over the past 12 years at the Royal Melbourne Hospital, Victoria, Australia, is reviewed. METHODS: Five patients with carotid cavernous fistulas were treated with embolization of the fistula via the surgically isolated SOV. RESULTS: Each patient had successful endovascular closure of the fistula using embolization via the SOV approach. CONCLUSIONS: Treatment of certain types of carotid cavernous fistulas that cannot be closed by the conventional endovascular (arterial and venous) approaches can be successfully closed by using a transvenous approach through the SOV.

Adult↗