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Biomedical subjects

John M Starr

Publications and source records attributed to John M Starr.

At least 37 records · Page 2Linked to original sources
PubMed2004

Cognitive reserve and the neurobiology of cognitive aging.

A hypothetical construct of "cognitive reserve" is widely used to explain how, in the face of neurodegenerative changes that are similar in nature and extent, individuals vary considerably in the severity of cognitive aging and clinical dementia. Intelligence, education and occupational level are believed to be major active components of cognitive reserve. Here, we summarize the main features of cognitive aging and their neuropathological correlates. We describe the neurobiology of cognitive aging and conclude that perturbations of neural health attributable to oxidative stress and inflammatory processes alone are insufficient to distinguish cognitive aging from Alzheimer's disease. We introduce the concept of cognitive reserve and illustrate its utility in explaining individual differences in cognitive aging. Structural and functional brain imaging studies suggest plausible neural substrates of cognitive reserve, probably involving processes that support neuroplasticity in the aging brain. The cognitive reserve hypothesis conforms with reported associations between early and mid life lifestyle choices, early education, lifelong dietary habit, leisure pursuits and the retention of late life mental ability.

Aging↗
PubMed2004

Size of the neocerebellar vermis is associated with cognition in healthy elderly men.

Cerebellar volumes show small positive correlations with cognitive ability in young adults, but no studies have examined this relationship in older adults. Furthermore, no studies have examined relationships between sizes of subareas of the cerebellum and cognitive ability. We hypothesized that size of the two areas of the neocerebellar vermis would correlate with a battery of eight cognitive tests in 50 men aged 65-70. Size of the neocerebellar areas of the vermis correlated positively with several cognitive tests (r's=.29-.37, p<.05), whilst sizes of other parts of the vermis did not correlate with any cognitive tests. Total cerebellar volumes correlated significantly with a test of nonverbal reasoning (r=.030, p=.42). These findings suggest a specific association of neocerebellar vermis size with variations in cognitive ability in older adults.

Aged↗
PubMed2004

Searching for genetic influences on normal cognitive ageing.

Differences in non-pathological cognitive ageing provide a useful case study for the opportunities and challenges facing cognitive science as it embraces advances in genetics. One replicated contributor to these differences is variability in the gene for apolipoprotein E. Genetic variations that influence neurodegenerative diseases, learning and memory, cardiovascular disease, and oxidative stress are among the candidates for influence on cognitive ageing differences. The area suffers the same problems as other domains in which quantitative trait loci are sought: uncertainty regarding the genetic architecture, unreliable strategies for candidate gene selection, lack of power leading to unreplicated findings, and poor characterisation of the phenotype. However, current progress in genetic knowledge, technology and informatics will contribute to progress in this important area.

Aging↗
PubMed2004

The impact of childhood intelligence on later life: following up the Scottish mental surveys of 1932 and 1947.

The Scottish Mental Surveys of 1932 and 1947 collected valid IQ-type test scores for almost everyone born in 1921 and 1936 and attending school on June 1, 1932 (N=89,498) and June 4, 1947 (N=70,805). These surveys are described. This research, using the surveys' data, examined (a) the stability of intelligence differences across the life span, (b) the determinants of cognitive change from childhood to old age, and (c) the impact of childhood intelligence on survival and health in old age. Surviving participants of the Scottish Mental Surveys were tested, and the surveys' data were linked with public and health records. Novel findings on the stability of IQ scores from age 11 to age 80; sex differences in cognitive aging; the dedifferentiation hypothesis of cognitive aging; and the effect of childhood IQ on all-cause and specific mortality, morbidity, and frailty in old age are presented.

Adolescent↗
PubMed2004

Birth weight and cognitive ability in childhood: a systematic review.

Individual differences in cognitive ability may in part have prenatal origins. In high-risk (low birth weight/premature) babies, birth weight correlates positively with cognitive test scores in childhood, but it is unclear whether this holds for those with birth weights in the normal range. The authors systematically reviewed literature on the relationship between normal birth weight (more than 2,500 g) and childhood intelligence in term (37-42-week gestation) deliveries. Six studies met the inclusion criteria, and the authors present a comprehensive narrative review of these studies. There was a small, consistent, positive association between birth weight and childhood cognitive ability, even when corrected for confounders. Parental social class accounted for a larger proportion of the variance than birth weight, and these 2 variables were largely independent.

Adolescent↗
PubMed2004

Apolipoprotein e gene variability and cognitive functions at age 79: a follow-up of the Scottish mental survey of 1932.

Apolipoprotein E (APOE) genotype is a possible influence on nonpathological cognitive aging. The authors studied 462 community-dwelling, 79-year-old people born in 1921, whose childhood IQ had been assessed in the Scottish Mental Survey of 1932 (Scottish Council for Research in Education, 1933). Adjusting for sex, childhood IQ, and self-reported illnesses, the authors found that those with an APOE e4 allele had significantly lower Wechsler Logical Memory (D. Wechsler, 1987) scores than those without an e4 allele. Those people with APOE s2/e3 genotypes had significantly higher Wechsler Logical Memory scores than e3/s3, who were significantly higher than e3/e4. Neither nonverbal reasoning nor verbal fluency were affected. In this sample, APOE genotype contributed to verbal memory in old age.

Aged↗
PubMed2004

Cognitive aging, childhood intelligence, and the use of food supplements: possible involvement of n-3 fatty acids.

BACKGROUND: Food supplement use is widely promoted, but little is known about the cognitive effects of food supplements. OBJECTIVE: We examined the effects of food supplement use on cognitive aging. DESIGN: This was an observational study of subjects born in 1936 whose mental ability was tested in 1947 and who were followed up in 2000-2001, at which time cognition, diet, food supplement use, and risk factors for vascular disease were assessed. In a nested case-control study, fish-oil users were matched with nonusers, and cognitive function was related to erythrocyte n-3 fatty acid composition. RESULTS: Childhood intelligence quotient (IQ) did not differ significantly by category of food supplement use (ie, none, fish oil, vitamins, and other). At the age of 64 y, cognitive function was higher in food supplement users than in nonusers before adjustment for childhood IQ. After adjustment for childhood IQ, digit symbol (mental speed) test scores were higher in food supplement users. Fish-oil supplement users consumed more vitamin C and vegetable and cereal fiber than did non-supplement-users. In a nested case-control study, erythrocyte membrane n-3 content was higher in fish-oil supplement users than in nonusers, but cognitive function did not differ significantly between groups. Total erythrocyte n-3 fatty acids and the ratio of docosahexaenoic acid to arachidonic acid was associated with better cognitive function in late life before and after adjustment for childhood IQ. CONCLUSIONS: Food supplement use and erythrocyte n-3 content are associated with better cognitive aging. If associations with n-3 content are causal, optimization of n-3 and n-6 fatty acid intakes could improve retention of cognitive function in old age.

Aging↗
PubMed2004

Childhood mental ability and blood pressure at midlife: linking the Scottish Mental Survey 1932 and the Midspan studies.

OBJECTIVES: To establish the relationship between childhood mental ability and adult hypertension. DESIGN: Retrospective cohort study. SETTING: Community. PARTICIPANTS: Non-clinical sample of people born in 1921 who participated in both the Scottish Mental Survey 1932 and the Midspan studies. Nine hundred and thirty-eight people were participants in both studies. MAIN OUTCOME MEASURES: Mid-life systolic and diastolic blood pressure, intelligence quotient (IQ) at age 11 years, sex, social class, height and weight. RESULTS: After adjustment for age, sex, social class, body mass index, height, cholesterol level and smoking, there remained a 3.15 mmHg decrease in systolic blood pressure and a 1.5 mmHg decrease in diastolic blood pressure for each standard deviation increase in childhood IQ. CONCLUSIONS: The association between hypertension and lower cognitive function in adulthood is partly accounted for by individual differences in childhood IQ.

Blood Pressure↗
PubMed2004

Diet and dementia.

The ageing brain adapts to the accumulation of damage caused by oxidative stress and inflammation. Adaptive processes include neuroprotective and neurorestorative mechanisms. Individual differences in susceptibility to dementia arise when these mechanisms are impaired or are overwhelmed by the molecular pathology of Alzheimer's disease. Neuroprotection relies upon extrinsic and intrinsic defences. An adequate intake of antioxidant micronutrients (eg, vitamin C and vitamin E) and anti-inflammatory macronutrients (eg, omega-3 polyunsaturated fatty acids) forms an essential component of extrinsic defences against brain ageing. There are many epidemiological data to support an association between an inadequate intake of antioxidants and/or fish oils (an important source of omega-3 polyunsaturated fatty acids) and a greater than expected incidence of late onset dementia. These associations are confounded by established links between poverty, poor diet and failing health, especially in old age. Such links may be sufficient to explain some of the effects of an inadequate diet on the retention of cognitive function and increased risk of dementia in old age. More compelling is the association between increased plasma homocysteine concentration and later increased risk of dementia. This association is possibly caused by an inadequate intake of vitamin B(12)/folate.

Antioxidants↗
PubMed2003

Lack of association between polymorphisms in angiotensin-converting-enzyme and methylenetetrahydrofolate reductase genes and normal cognitive ageing in humans.

The hypothesis that polymorphisms at two candidate genes that code for angiotensin-converting-enzyme (ACE) and methylenetetrahydrofolate reductase (MTHFR) are associated with normal cognitive ageing was tested using a sample (n=536) of healthy 80-year-old people who were born in 1921 and whose cognitive ability at age 11 was measured in the Scottish Mental Survey 1932. Cognitive ability at age 11 and age 80 was assessed using the Moray House Test. Cognitive ageing was defined as the change in IQ from age 11 to 80. There was no significant association between the tested ACE and MTHFR polymorphisms and IQ score at age 11, IQ at age 80, and IQ change (all P>0.05). The ACE genotypes deviated significantly from Hardy-Weinberg equilibrium proportions (P=0.02), which could indicate that this gene is under selection. Polymorphisms at the two studied genes are unlikely to be risk factors for normal cognitive ageing.

Aged↗
PubMed2003

Childhood and current cognitive function in healthy 80-year-olds: a DT-MRI study.

Diffusion tensor MR imaging (DT-MRI) yields information on early pathological changes in white matter of the ageing brain which may correlate with cognitive function. However, because individuals vary in their cognitive ability, a measurement of prior cognition from youth is required to understand fully the significance of MR imaging changes associated with ageing. Here, diffusion tensor parameters and cognitive function were measured in a cohort of 30 older subjects whose cognitive ability was measured at age 11 and 80. There was a significant correlation between diffusion anisotropy measured in the centrum semiovale at age 80 and mental ability determined at age 11 and 80. These novel results suggest, that MR imaging studies of white matter structure and its relationship to mental ability in ageing should control for early life cognition.

Aged↗
PubMed2003

Associations with successful ageing in the "Healthy Old People in Edinburgh" cohort: being well, fit and healthy.

BACKGROUND AND AIMS: Six hundred and three community-resident, healthy, unmedicated people aged 70 years and over had psychometric testing and blood pressure measured in 1990-1. Participants were followed up in 1994-5, 1997-8 and in this fourth wave of the project, 1999-2000, to determine key predictors of, and associations with successful ageing. METHODS: Current status of all cohort participants was determined. Those traced and alive were invited for re-assessment. Those who agreed underwent psychometric testing, including memory and fluid intelligence tests, a number of physiological measurements, including blood pressure, grip strength and respiratory function, and questionnaires were administered enquiring about disability, self-esteem, and a range of socioeconomic and socioenvironmental items. RESULTS: At Wave 4, 201 participants were visited and re-tested adequately. During follow-up, mortality (N = 210) was predicted by gender, occupation, premorbid intelligence and blood pressure. Disability related to age, weight, respiratory function, grip strength and current mental ability. A model of health was developed that comprised dimensions of medical well-being (absence of disease), physiological fitness and self-perceived health. The latter related strongly to disability and pre-morbid intelligence. Except for memory score at Wave 3, medical well-being related poorly to any predictor variable from Waves 1-3. Physiological fitness related to age, gender and current mental ability. CONCLUSIONS: The concept of successful ageing is complex, but this cohort of older people related their perceived health closely to lack of disability. In this cohort, current socioeconomic and socioenvironmental factors were not strongly linked with health at this age.

Aged↗
PubMed2003

Quality of Life in healthy old age: relationships with childhood IQ, minor psychological symptoms and optimism.

BACKGROUND: The aim of this study was to examine relationships in old age between Quality of Life (QoL), childhood IQ, current cognitive performance and minor psychological symptoms, and to estimate possible contributions to these relationships made by sex, education, socioeconomic deprivation, current living group, sex, and balance and 6m walk time. METHODS: We conducted a follow-up study on 88 community residents without dementia who were survivors of the Aberdeen City 1921 birth cohort. QoL was measured by the Schedule for the Evaluation of Individual QoL-Direct Weighting (SEIQoL-DW), current cognition by MMSE and Raven's Progressive Matrices (RPM), childhood IQ, minor psychological symptoms as assessed by the Hospital Anxiety and Depression Scale (HADS), and optimism by the Life Orientation Test (LOT); we included balance, 6m walk time and demographic data. RESULTS: QoL was better in men than in women. Women reported more anxiety and depression. QoL correlated significantly with current cognition measured by RPM, childhood intelligence, anxiety and depressive symptoms, optimism and balance. The best model to predict QoL relied on childhood intelligence (13.4% of the variance) and was improved by addition of HADS (8.8 %) and LOT (4.8 %). Other variables did not contribute to the prediction of QoL. CONCLUSION: In the absence of dementia, childhood IQ, HADS and LOT explain 26.9% of the variance in QoL as reported by community-resident old people. The direction of association between current anxiety and depressive symptoms and lower QoL is uncertain. Lower childhood IQ may contribute to coping less well with later life. Lower QoL is not an invariable concomitant of mild cognitive decline.

Activities of Daily Living↗
PubMed2003

Risk factors for Clostridium difficile colonisation and toxin production.

OBJECTIVES: to examine risk factors for patients becoming Clostridium difficile culture and toxin positive. DESIGN: prospective cohort study. SETTING: two medicine for the elderly wards. PARTICIPANTS: patients admitted to the wards over a 17-month period. MEASUREMENT: presence of Clostridium difficile on culture of stool specimens and toxins A and/or B. Patient's age, sex, source of admission, antibiotic, laxative, antacid and steroid use, presence/absence of colonic disease, neoplasia, leukaemia and nasogastric or percutaneous endoscopic gastrostomy tube feeding. RESULTS: 390 of 865 patients admitted provided a total of 1003 faecal specimens. Age (OR 1.04, 95% CI 1.001-1.07 per year), admission from another hospital (OR 2.13, 95% CI 1.29-3.50), non-cephalosporin antibiotics (OR 2.08, 95% CI 1.25-3.46) and cephalosporin use (OR 8.45, 95% CI 2.99-23.9) increased risk of becoming Clostridium difficile culture positive. Becoming toxin-positive was associated with antibiotic use only (OR 3.02, 95% CI 1.15-7.92), specifically amoxycillin (OR 8.72, 95% CI 1.66-45.9) and cephalosporins other than ceftriaxone (OR 7.28, 95% CI 1.34-39.6). CONCLUSION: different risk factors are important for the two stages leading to Clostridium difficile diarrhoea. Age, source of admission and third generation cephalosporins increase risk of becoming culture positive, whilst only antibiotic use is associated with the step of becoming toxin-positive. Understanding these differential risks may aid infection control strategies.

Aged↗
PubMed2003

Changes in sensitivity patterns to selected antibiotics in Clostridium difficile in geriatric in-patients over an 18-month period.

Clostridium difficile-associated disease continues to be a major problem in hospitals and long-term care facilities throughout the developed world. Administration of certain antibiotics such as amoxycillin, oral cephalosporins and clindamycin is associated with the greatest risk of developing C. difficile disease. The two antibiotics used for treatment of C. difficile disease are vancomycin and metronidazole, to which there is currently very little resistance. Randomly selected isolates (186) from 90 patients being investigated during an 18-month epidemiological study into the disease were tested for their susceptibility to vancomycin, metronidazole, amoxycillin, clindamycin, cefoxitin and ceftriaxone by the NCCLS agar dilution method. There was a narrow range of MIC for the two treatment agents (vancomycin and metronidazole), from 0.5 to 4 microg ml(-1), with no evidence of resistance. All strains were resistant to cefoxitin (MIC 64-256 microg ml(-1)), the antibiotic used in most selective media. All strains were of similar sensitivity to amoxycillin (MIC(90)= 4 microg ml(-1)). Most strains were resistant to ceftriaxone (MIC > or = 64 microg ml(-1)) or of intermediate resistance (MIC > or = 32 microg ml(-1)), with only two sensitive strains (MIC 16 microg ml(-1)). Clindamycin resistance was common, with 67 % of strains resistant (MIC > or = 8 microg ml(-1)), 25 % with intermediate resistance (MIC > or = 4 microg ml(-1)) and only 8 % sensitive (MIC < or = 2 microg ml(-1)). Twelve isolates from six different patients had very high resistance to clindamycin (MIC > or = 128 microg ml(-1)). Multiple isolates from the same patient, taken at different times, showed changes in susceptibility patterns over time. The only major change in susceptibility over the time-period was in clindamycin resistance; some strains appeared to become more resistant while others became less resistant. No differences were seen in the MIC(50) and MIC(90) of the different S-types of C. difficile identified, although some S-types were present in very small numbers. There was no correlation between the antibiotics prescribed and susceptibility.

Aged↗
PubMed2002

Cognitive change and the APOE epsilon 4 allele.

There is a marked variation in whether people retain sufficient cognitive function to maintain their quality of life and independence in old age, even among those without dementia, so it would be valuable to identify the determinants of normal age-related cognitive change. We have retested non-demented 80-year-olds who were participants in the Scottish Mental Survey of 1932, and find that the variation in their non-pathological cognitive change from age 11 to 80 is related to their apolipoprotein E (APOE) genotype. This effect of the APOE epsilon 4 allele on normal cognitive ageing may be mediated by a mechanism that is at least partly independent of its predisposing effect towards Alzheimer's disease.

Adolescent↗
PubMed2002

Efficiency of temporal order discrimination as an indicator of bradyphrenia in Parkinson's disease: the inspection time loop task.

To investigate the bradyphrenia hypothesis of Parkinson's disease (PD), 32 patients undertook an information-processing task which measured their efficiency of temporal order discrimination. Their performance was compared with 31 non-PD controls matched on age, sex, years of full-time education and pre-morbid IQ. The task was novel and designed to be sensitive to the clinical phenomenon of bradyphrenia (slowing of mental abilities), in the context of temporal order discrimination without confounding from motor ability deficits. The test (the inspection time loop task; ITloop) required judgements as to the temporal sequence of four single letters. The stimulus duration of the letters in each sequence ranged from 100 to 700ms. The PD group had a significantly lower mean score on the ITloop task than did controls (P=0.02). PD patients perform more poorly on temporal order discrimination judgements even when the task makes no motor demands.

Aged↗