Cognitive activity and the cognitive morbidity of Alzheimer disease

OBJECTIVE

To test the hypothesis that frequent cognitive activity predicts slower cognitive decline before dementia onset in Alzheimer disease (AD) and faster decline thereafter.

METHODS

As part of a longitudinal cohort study, older residents of a geographically defined population were assessed at 3-year intervals with brief cognitive performance tests from which a composite measure of global cognition was derived. After each wave of testing, a subset was sampled for clinical evaluation. The present analyses are based on 1,157 participants. They were free of dementia at study enrollment at which time they rated frequency of participation in common cognitively stimulating activities from which a previously validated summary measure was derived. They were sampled for clinical evaluation a mean of 5.6 years after enrollment and subsequently followed a mean of 5.7 years with brief cognitive performance testing at 3-year intervals.

RESULTS

On clinical evaluation, 614 people had no cognitive impairment, 395 had mild cognitive impairment, and 148 had AD. During follow-up, the annual rate of global cognitive decline in persons without cognitive impairment was reduced by 52% (estimate = 0.029, SE = 0.010, p = 0.003) for each additional point on the cognitive activity scale. In the mild cognitive impairment group, cognitive decline rate was unrelated to cognitive activity (estimate = -0.019, SE = 0.018, p = 0.300). In AD, the mean rate of decline per year increased by 42% (estimate = 0.075, SE = 0.021, p < 0.001) for each point on the cognitive activity scale.

CONCLUSION

Mentally stimulating activity in old age appears to compress the cognitive morbidity associated with AD by slowing cognitive decline before dementia onset and hastening it thereafter.

Temporal course of depressive symptoms during the development of Alzheimer disease

OBJECTIVE

To characterize change in depressive symptoms before and after the onset of dementia in Alzheimer disease (AD).

METHOD

We used data from the Chicago Health and Aging Project, a longitudinal cohort study of risk factors for AD in a geographically defined population of old people. Two subsets were analyzed. In 357 individuals who developed incident AD during the study, self-report of depressive symptoms (Center for Epidemiologic Studies Depression Scale) was obtained at 3-year intervals for a mean of 8 to 9 years. In 340 individuals who agreed to annual data collection, informant report of depressive symptoms (Hamilton Depression Rating Scale) was obtained for a mean of 3 years after a diagnosis of AD (n = 107), mild cognitive impairment (n = 81), or no cognitive impairment (n = 152).

RESULTS

The incident AD group reported a barely perceptible increase in depressive symptoms during 6 to 7 years of observation before the diagnosis (0.04 symptoms per year) and no change during 2 to 3 years of observation after the diagnosis except for a slight decrease in positive affect. In those with annual follow-up, neither AD nor its precursor, mild cognitive impairment, was associated with change in informant report of depressive symptoms during a mean of 3 years of observation.

CONCLUSION

Depressive symptoms show little change during the development and progression of AD to a moderate level of dementia severity.

Cognitive decline in incident Alzheimer disease in a community population

OBJECTIVE

To measure the cognitive consequences of incident Alzheimer disease (AD) in older African American and white subjects.

METHODS

Data are from the Chicago Health and Aging Project, a longitudinal cohort study of older white and black persons residing in a geographically defined community. At 3-year intervals, the entire study population completed 4 brief cognitive tests, from which a previously established composite measure of global cognition was derived, and a subset underwent detailed clinical evaluation that supported clinical classification of mild cognitive impairment, dementia, and AD. We used mixed-effects models to examine change in cognitive function following the diagnostic evaluation.

RESULTS

On clinical evaluation, 614 persons were found to have no cognitive impairment, 395 had mild cognitive impairment, and 149 had AD (88.5% mild); 10 persons with other dementias were excluded from analyses. During up to 11 years of observation following the clinical evaluation (mean = 5.5, SD = 2.5), the composite measure of global cognition declined a mean of 0.042 unit per year (SE = 0.008, p < 0.001) in those with no cognitive impairment. In comparison to the no cognitive impairment group, the annual rate of decline was increased more than twofold in mild cognitive impairment (estimate = 0.086, SE = 0.011, p < 0.001) and more than fourfold in AD (estimate = 0.173, SE = 0.020, p < 0.001). Results did not reliably vary by race, sex, or age.

CONCLUSIONS

Alzheimer disease has a devastating impact on cognition, even in its prodromal stages, with comparable effects in African American and white persons.

Diamond-metal contacts: interface barriers and real-time characterization

A review of diamond-metal contacts is presented with reference to reported values of interfacial potential (Schottky) barriers and their dependence on macroscopic and microscopic properties of the diamond surface, the interface and the metal. No simple model can account for the overall spread of p-diamond barriers, although there are, for certain metals, correlations with metal electronegativity, interface chemistry and diamond surface preparation. Detailed studies are presented for a selected contact (Al-p-diamond) using real-time monitoring during metal growth from sub-nanometre to bulk films and subsequent in situ heating to 1000 °C. This contact, prepared in a clean vacuum environment on characterized single-crystal substrates, provides a case study for a combined in situ electrical and spectroscopic investigation using IV measurements for macroscopic diodes and real-time photoelectron spectroscopy for nanoscale metal films. Band bending during growth leads to a rectifying contact with a measured IV barrier height of 1.05 V and an ideality factor of 1.4. A transition from layered to clustered growth of the metal film is revealed in the real-time measurements and this is confirmed by AFM. For the annealed contact, a direct correlation is revealed by real-time photoemission between the onset of interfacial carbide formation and the change from a rectifying to an ohmic contact at 482 °C.

Educational attainment and cognitive decline in old age

BACKGROUND

Level of education is a well-established risk factor for Alzheimer disease but its relation to cognitive decline, the principal clinical manifestation of the disease, is uncertain.

METHODS

More than 6,000 older residents of a community on the south side of Chicago were interviewed at approximately 3-year intervals for up to 14 years. The interview included administration of four brief tests of cognitive function from which a previously established composite measure of global cognition was derived. We estimated the associations of education with baseline level of cognition and rate of cognitive change in a series of mixed-effects models.

RESULTS

In an initial analysis, higher level of education was related to higher level of cognition at baseline, but there was no linear association between education and rate of change in cognitive function. In a subsequent analysis with terms to allow for nonlinearity in education and its relation to cognitive decline, rate of cognitive decline at average or high levels of education was slightly increased during earlier years of follow-up but slightly decreased in later years in comparison to low levels of education. Findings were similar among black and white participants. Cognitive performance improved with repeated test administration, but there was no evidence that retest effects were related to education or attenuated education's association with cognitive change.

CONCLUSIONS

The results suggest that education is robustly associated with level of cognitive function but not with rate of cognitive decline and that the former association primarily accounts for education's correlation with risk of dementia in old age.

Relation of NSAIDs to incident AD, change in cognitive function, and AD pathology

OBJECTIVE

To examine the relation of nonsteroidal anti-inflammatory drugs (NSAIDs) to incident Alzheimer disease (AD), change in cognition, and AD pathology.

METHODS

Participants were 1,019 older Catholic clergy followed up annually for up to 12 years (mean baseline age = 75.0 years, education = 18.1 years, Mini-Mental State Examination score = 28.5), enrolled in the Religious Orders Study, a longitudinal clinical-pathologic study of aging and AD. Clinical evaluations allowed for AD classification and assessment of global cognition and five cognitive domains. NSAIDs were identified by direct medication inspection at baseline and follow-up evaluations. Neuropathologic data were available on 328 deceased participants. AD pathology was summarized as a global measure and as measures of neuritic plaques, diffuse plaques, and neurofibrillary tangles. We used Cox proportional hazards models and mixed models for incident AD and cognitive decline, respectively, and logistic and linear regression for pathologic outcomes, adjusted for age, sex, and education.

RESULTS

Overall, we found no apparent relation of NSAIDs to incident AD (n = 209 cases), change in cognition, or AD pathology. The hazard ratio of incident AD was 1.19 (95% CI 0.87-1.62) comparing those using NSAIDs with those not using NSAIDs at baseline, and 0.84 (95% CI 0.63-1.11) for specific use of aspirin. Findings were similar in analyses in which we considered NSAID use during follow-up. NSAIDs were not related to change in cognition (all p values > 0.14). There was no relation of NSAIDs to global AD pathology or plaques or tangles.

CONCLUSION

These data do not support a strong relation between nonsteroidal anti-inflammatory drugs and Alzheimer disease or cognition. Consistent findings across clinical and pathologic outcomes provide additional confidence in these results.

Statins, incident Alzheimer disease, change in cognitive function, and neuropathology

OBJECTIVE

To examine the relation of statins to incident Alzheimer disease (AD) and change in cognition and neuropathology.

METHODS

Participants were 929 older Catholic clergy (68.7% women, mean baseline age 74.9 years, education 18.2 years, Mini-Mental State Examination 28.5) free of dementia, enrolled in the Religious Orders Study, a longitudinal clinical-pathologic study of AD. All agreed to brain autopsy at time of death and underwent annual structured clinical evaluations, allowing for classification of AD and assessment of cognition (based on 19 neuropsychological tests). Statins were identified by direct medication inspection. Neuropathologic data were available on 262 participants. All macroscopic chronic cerebral infarctions were recorded. A measure of global AD pathology was derived from silver stain, and separate measures of amyloid and tangles were based on immunohistochemistry. We examined the relation of statins to incident AD using Cox proportional hazards, change in cognition using mixed effects models, and pathologic indices using logistic and linear regression.

RESULTS

Statin use at baseline (12.8%) was not associated with incident AD (191 persons, up to 12 follow-up years), change in global cognition, or five separate cognitive domains (all p values > 0.20). Statin use any time prior to death (17.9%) was not related to global AD pathology. Persons taking statins were less likely to have amyloid (p = 0.02). However, among those with amyloid, there was no relation of statins to amyloid load. Statins were not related to tangles or infarction.

CONCLUSIONS

Overall, statins were not related to incident Alzheimer disease (AD) or change in cognition, or continuous measures of AD pathology or infarction.

Body mass index and cognitive decline in a biracial community population

OBJECTIVE

To examine whether a higher body mass index (BMI) in older adults is associated with greater cognitive decline.

METHODS

A longitudinal study was conducted from 1993 to 2003 with an average follow-up of 6.4 years of a biracial community population on the south side of Chicago. Participants were 3,885 community-dwelling adults aged 65 and older who participated in at least two assessments. A composite measure of global cognitive function was used which was derived from the average of standardized scores from four cognitive tests.

RESULTS

There was a significant curvilinear association between BMI and cognitive function scores at baseline for both black (= -0.0014, p = 0.001) and non-black subjects (= -0.0011, p = 0.002). In a mixed model adjusted for age, sex, race, and education, higher BMI was associated with less cognitive decline in both black (= 0.0013, p = 0.009) and non-black subjects (= 0.0021, p = 0.006). Adjusting for comorbid illnesses did not change these findings substantially. However, the associations were much smaller and no longer significant among participants with no cognitive decline at baseline as measured by a Mini-Mental State Examination score of greater than 24.

CONCLUSIONS

The findings suggest that greater body mass index in old age is not predictive of cognitive decline in a cognitively unimpaired community population.

Associations of vegetable and fruit consumption with age-related cognitive change

OBJECTIVE

To examine the association between rates of cognitive change and dietary consumption of fruits and vegetables among older persons.

METHODS

The authors conducted a prospective cohort study of 3,718 participants, aged 65 years and older of the Chicago Health and Aging Project. Participants completed a food frequency questionnaire and were administered at least two of three cognitive assessments at baseline, 3-year, and 6-year follow-ups. Cognitive function was measured using the average z-score of four tests: the East Boston Tests of immediate memory and delayed recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test.

RESULTS

The mean cognitive score at baseline for the analyzed cohort was 0.18 (range: -3.5 to 1.6), and the overall mean change in score per year was a decline of 0.04 standardized units. In mixed effects models adjusted for age, sex, race, and education, compared with the rate of cognitive decline among persons in the lowest quintile of vegetable intake (median of 0.9 servings/day), the rate for persons in the fourth quintile (median, 2.8 servings/day) was slower by 0.019 standardized units per year (p = 0.01), a 40% decrease, and by 0.018 standardized units per year (p = 0.02) for the fifth quintile (median, 4.1 servings/day), or a 38% decrease in rates. The association remained significant (p for linear trend = 0.02) with further control of cardiovascular-related conditions and risk factors. Fruit consumption was not associated with cognitive change.

CONCLUSION

High vegetable but not fruit consumption may be associated with slower rate of cognitive decline with older age.

Mild cognitive impairment is related to Alzheimer disease pathology and cerebral infarctions

OBJECTIVES

To examine the extent to which persons with mild cognitive impairment have intermediate levels of Alzheimer disease (AD) pathology, cerebral infarcts, and Lewy body disease.

METHODS

A total of 180 Catholic clergy participating in the Religious Orders Study underwent annual detailed evaluation and brain autopsy. Blocks of midfrontal, superior temporal, medial temporal lobe, inferior parietal, entorhinal cortex, hippocampus, and substantia nigra were paraffin embedded, and sectioned at 6 mum. Cortical neuritic plaques, diffuse plaques, and neurofibrillary tangles were visualized with Bielschowsky silver stain, and counted and summarized to yield a Braak stage, Consortium to Establish a Registry for Alzheimer's Disease (CERAD) diagnosis, National Institute on Aging (NIA)-Reagan diagnosis, and composite measure of AD pathology. The authors recorded the number and location of all gross chronic cerebral infarctions. Lewy bodies were identified with antibodies to alpha-synuclein. Multiple regression analyses were used to examine the relation of AD pathology and cerebral infarctions to clinical diagnosis proximate to death, controlling for age, sex, and education.

RESULTS

A total of 37 had mild cognitive impairment, 60 did not have cognitive impairment, and 83 had dementia proximate to death. Nearly all persons had at least some AD pathology. Cerebral infarctions were present in 35.2%, and 15.6% had Lewy body disease. Persons with mild cognitive impairment were intermediate in terms of Braak stage and CERAD and NIA-Reagan neuropathologic criteria for AD compared to the other two groups. In multiple regression analyses, persons with mild cognitive impairment had intermediate levels of AD pathology from those without cognitive impairment and those with dementia (test for trend, F = 45.2, p < 0.001). Further, the relation between cognition and AD pathology in persons with mild cognitive impairment did not differ significantly from the relation between cognition and AD pathology in persons with dementia or those without cognitive impairment. Persons with mild cognitive impairment also had intermediate levels of cerebral infarctions (test for trend, p = 0.04). Only 3 (8.1%) persons with mild cognitive impairment had Lewy body disease.

CONCLUSION

These data suggest that mild cognitive impairment may be the earliest clinical manifestation of common age-related neurologic diseases.

Hallucinations, cognitive decline, and death in Alzheimer's disease

The relation of psychotic symptoms to cognitive decline and mortality in Alzheimer's disease (AD) was examined during a mean of 2.2 years in 478 persons selected from clinical settings. Psychotic symptoms were ascertained at baseline and cognition was assessed semiannually with nine tests from which a global measure was formed. In analyses that controlled for age, sex, race, and education, hallucinations (29.6%), especially visual ones, were associated with more rapid global cognitive decline and increased mortality, even after controlling for baseline level of cognition and use of antipsychotic medication, and the association with mortality increased with higher level of education. Delusions and misperceptions were not strongly related to cognitive decline or mortality. The results suggest that hallucinations in Alzheimer's disease, particularly visual ones, are associated with more rapid progression.

Socioeconomic Characteristics of the Community in Childhood and Cognition in Old Age

We examined the relation of early life socioeconomic circumstances to cognition in older residents of a biracial urban community. Participants had brief cognitive testing three times at approximately 3-year intervals. At baseline, information about early life household and county socioeconomic level was collected. In mixed-effects models adjusted for age, sex, race, and education, both early life household and county socioeconomic levels were positively associated with baseline level of cognition but unrelated to cognitive decline. The results suggest that socioeconomic conditions in early life are associated with level of cognitive function in old age but not with rate of cognitive decline.

Change in body mass index and risk of incident Alzheimer disease

OBJECTIVE

To examine the association of change in body mass index (BMI) with risk of Alzheimer disease (AD).

METHODS

Nine hundred eighteen older Catholic clergy participating in the Religious Orders Study without dementia at baseline were studied. Outcome measures were the clinical diagnosis of AD and change in cognitive function.

RESULTS

During a mean follow-up of 5.5 years, 151 persons developed AD. BMI averaged 27.4 at baseline and declined in about half the participants. In a proportional hazards model adjusted for age, sex, and education, each 1-unit less of BMI at baseline was associated with about a 5% increase in the risk of AD (hazard ratio = 0.944; 95% CI = 0.908 to 0.981), and each 1-unit annual decline in BMI (about the 10th percentile) was associated with about a 35% increase in the risk of AD compared with a person experiencing no change in BMI (about the 50th percentile) (hazard ratio = 0.730; 95% CI = 0.625 to 0.852). The results were similar after controlling for chronic diseases and excluding persons who developed AD during the first 4 years of observation. Random effects models showed that the rate of cognitive decline increased by about 8% for each 1-unit less of BMI at baseline and declined an additional 40%/year in persons losing 1 unit of BMI/year compared with those with no change in BMI.

CONCLUSION

Declining body mass index (BMI) is associated with increased risk of incident Alzheimer disease (AD). Loss of BMI may reflect pathologic processes that contribute to the subsequent development of AD.

Social resources and cognitive decline in a population of older African Americans and whites

OBJECTIVE

To examine the relation of social resources and cognitive decline in older adults.

METHODS

Data are from the Chicago Health and Aging Project, an epidemiologic study of risk factors for Alzheimer disease (AD) and other common conditions in a geographically defined population of older persons. The sample consisted of 6,102 non-Hispanic African Americans (61.2%) and whites, aged > or = 65, who underwent up to three interviews during an average of 5.3 years of follow-up. Each interview included administration of four cognitive function tests from which a composite measure of cognition was formed. Social networks were based on the number of children, relatives, and friends seen at least once a month. Social engagement was measured with four items related to social and productive activity.

RESULTS

Higher number of social networks and level of social engagement were positively correlated with initial level of cognitive function (networks estimate = 0.003, engagement estimate = 0.060, both p < 0.001). Both resources were also associated with a reduced rate of cognitive decline. A high (90th percentile) number of networks reduced the rate of decline by 39% compared to a low level (10th percentile), and high social engagement reduced decline by 91%. These relations remained after controlling for socioeconomic status, cognitive activity, physical activity, depressive symptoms, and chronic medical conditions.

CONCLUSIONS

Greater social resources, as defined by social networks and social engagement, are associated with reduced cognitive decline in old age.

The apolipoprotein E epsilon4 allele increases the odds of chronic cerebral infarction [corrected] detected at autopsy in older persons

BACKGROUND AND PURPOSE

Studies investigating the relation of the apolipoprotein E (apoE) epsilon4 allele to clinical stroke and to vascular changes on magnetic resonance imaging have been conflicting. Little data are available regarding the relation of apoE epsilon4 to cerebral infarctions documented on postmortem examination.

METHODS

We studied the apoE epsilon4 allele in 214 deceased members of the Religious Orders Study, a longitudinal clinical-pathologic study of aging and Alzheimer disease. The apoE genotype was determined using DNA from lymphocytes. Brains were removed a median of 5 hours (interquartile range, 5.5) after death. At postmortem examination, age, location, and size of macroscopic chronic cerebral infarctions were recorded from 1-cm coronal slabs after paraformaldehyde fixation. We also examined 20-microm paraffin-embedded sections of midfrontal and calcarine cortex for amyloid angiopathy on a scale of 1 to 4.

RESULTS

Subjects included 96 males and 118 females with a mean age at death of 86 years (SD, 7). Sixty-five subjects (30.4%) had at least 1 apoE epsilon4 allele and 76 (35.5%) exhibited cerebral infarctions. More than 74% of the subjects exhibited amyloid angiopathy with a mean score of 1.4+/-1.2. After controlling for age and sex, apoE epsilon4 increased the odds of cerebral infarction by 2.3-fold (95% CI, 1.2 to 4.2). apoE epsilon4 increased the odds of cortical 3.2-fold (95% CI, 1.3 to 7.7) and subcortical infarctions 2.3-fold (95% CI, 1.2 to 4.5). The effect was unchanged after accounting for amyloid angiopathy.

CONCLUSIONS

apoE epsilon4 increases the odds of chronic cerebral infarction detected at autopsy in older persons.

Proneness to psychological distress and risk of Alzheimer disease in a biracial community

Persons without dementia residing in a biracial community completed a brief scale of proneness to psychological distress, and 1,064 were subsequently examined for incident Alzheimer disease (AD) 3 to 6 years later. In analyses controlling for selected demographic and clinical variables, persons prone to distress were 2.4 times more likely to develop AD than persons not distress prone. This effect was substantially stronger in white persons compared to African Americans.

Education and the course of cognitive decline in Alzheimer disease

OBJECTIVE

To test the hypothesis that higher level of education is related to more rapid cognitive decline in Alzheimer disease (AD).

METHODS

Participants are older persons with clinically diagnosed AD recruited from health care facilities in the Chicago area. At 6-month intervals for up to 4 years, they underwent uniform structured clinical evaluations that included administration of nine cognitive performance tests from which a composite measure of global cognition was derived. Analyses are based on 494 persons with follow-up data (89.3% of those eligible). In mixed models that allowed for linear and nonlinear decline, the authors first accounted for the effects of age on cognition and then tested the relation of education to rate of cognitive decline.

RESULTS

Global cognitive decline had linear and nonlinear components, resulting in a gradually accelerating course of decline. Age was related to linear but not nonlinear decline, with more rapid decline observed in younger compared with older persons. Higher educational level was related to more rapid global cognitive decline, as hypothesized, with education related to the nonlinear but not the linear component of decline.

CONCLUSION

Higher educational attainment is associated with a slightly accelerated rate of cognitive decline in Alzheimer disease.

Diabetes mellitus and progression of rigidity and gait disturbance in older persons

BACKGROUND

Parkinsonian-like signs, including rigidity, gait disturbance, and bradykinesia, are common and progressive in old age and are associated with morbidity and mortality. Few risk factors for these signs have been identified. Diabetes mellitus, also a common chronic condition in old age and known to be associated with physical and neurologic disability, may be associated with parkinsonian-like signs.

OBJECTIVE

To examine the relation of diabetes to four parkinsonian-like signs.

METHODS

Participants were 822 older Catholic clergymen and women who were without clinically diagnosed Parkinson disease or dementia at baseline. For up to 9 years, they had uniform annual evaluations, which included a modified version of the motor portion of the Unified Parkinson's Disease Rating Scale, from which previously established measures of four specific parkinsonian-like signs were derived. Participants were evaluated for the presence of diabetes, based on direct medication inspection and history.

RESULTS

Diabetes was present in 128 (15.6%) participants. In random effects models controlling for age, sex, and education, diabetes was associated with worsening rigidity (p < 0.01) and gait (p < 0.05), over an average of 5.6 years of follow-up, but not with change in bradykinesia or tremor. The presence of stroke did not substantially affect the association of diabetes with rigidity but reduced the association of diabetes with gait to a trend (p = 0.08).

CONCLUSION

Diabetes may be a previously unrecognized risk factor for progression of parkinsonian-like signs in older persons.

Depressive symptoms, clinical AD, and cortical plaques and tangles in older persons

BACKGROUND

Depressive symptoms in old age have been associated with risk of Alzheimer disease (AD), but it is uncertain whether they are an independent risk factor for disease or an early clinical sign of its underlying pathology.

METHODS

A group of 130 older Catholic nuns, priests, and brothers underwent detailed annual clinical evaluations and brain autopsy at death. The evaluations included administration of a modified 10-item Center for Epidemiologic Studies Depression Scale (CES-D) and 19 cognitive performance tests and clinical classification of dementia and AD. On postmortem examination, neuritic plaques, diffuse plaques, and neurofibrillary tangles in tissue samples from four cortical regions were counted, and a previously established composite measure of cortical plaque and tangle density (range 0 to 2.98) was derived. All analyses were adjusted for age, sex, and education.

RESULTS

Participants reported a mean 1.5 depressive symptoms (SD 1.6) on the CES-D scale averaged across evaluations. In a logistic regression model, the odds of clinically diagnosed AD proximate to death increased by 1.33 (95% CI 1.01 to 1.76) for each depressive symptom and by 8.41 (95% CI 3.49 to 20.26) for each unit on the composite measure of pathology. In subsequent analyses, depressive symptoms were not related to level of pathology and did not modify the relation of pathology to clinical AD. In a series of linear regression models that controlled for pathology, depressive symptoms were related to level of cognitive function proximate to death and did not modify the association of pathology with cognition.

CONCLUSION

The association of depressive symptoms with clinical AD and cognitive impairment appears to be independent of cortical plaques and tangles.

Dietary fat intake and 6-year cognitive change in an older biracial community population

OBJECTIVE

To examine whether consumption of different types of fat is associated with age-related change in cognition.

METHODS

The authors related fat consumption to 6-year change in cognitive function among 2,560 participants of the Chicago Health and Aging Project, ages 65 and older, with no history of heart attack, stroke, or diabetes at baseline. Fat intake was measured by food frequency questionnaire. Cognitive function was measured at baseline and 3-year and 6-year follow-ups, using the average z score of four cognitive tests: the East Boston Tests of Immediate and Delayed Recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test.

RESULTS

In separate mixed models adjusted for demographic and cardiovascular risk factors and intakes of antioxidant nutrients and other dietary fats, higher intakes of saturated fat (p for trend = 0.04) and trans-unsaturated fat (p for trend = 0.07) were linearly associated with greater decline in cognitive score over 6 years. These associations became stronger in analyses that eliminated persons whose fat intake changed in recent years or whose baseline cognitive scores were in the lowest 15%. Inverse associations with cognitive decline were observed in these latter restricted analyses for high intake of monounsaturated fat and a high ratio of polyunsaturated to saturated fat intake. Intakes of total fat, vegetable and animal fats, and cholesterol were not associated with cognitive change.

CONCLUSION

A diet high in saturated or trans-unsaturated fat or low in nonhydrogenated unsaturated fats may be associated with cognitive decline among older persons.

Enhancement in the absorption of water and electrolytes from rat intestine byHemidesmus indicus R. Br. root(water extract)

Hemidesmus indicus root in the form of suspension in water (10 mg/ml) containing 15.5 mM NaCl, 3 mM KCl and 12 mM glucose, when injected into the ligated jejunal sac (1 ml/sac) of rat, increased the absorption of water, Na(+) and K(+) (but not glucose) from the sac. This bioactivity was present in the water extract (5 or 10 mg/sac) of the root and not in the hexane extract. In contrast, the ethanol extract decreased the absorption of water and electrolytes from the jejunal sac. The effect of water extract was not affected by heat at 100 degrees C for 30 min. Intraperitoneal administration of the water extract (50 to 200 mg/kg) was devoid of any significant effect on the jejunal absorption. Neither the root suspension nor the water extract (125-500 mg/kg) showed any significant anti-ulcer and diuretic activities in rats. The intestinal motility was also not influenced by the root (water extract) when tested in mice. The present study indicates that H. indicus root powder or its water extract can be incorporated in oral rehydrating salt solution (ORS) for increasing its anti-diarrhoeal efficacy.

Influence of behavioral symptoms on rates of institutionalization for persons with Alzheimer's disease

BACKGROUND

Recent studies indicate that behavioral symptoms may play a key role in decisions to institutionalize persons with Alzheimer's disease (AD), but the specific types of behavior that contribute to this increased risk have not been reliably identified. The relationship between behavioral symptoms and time to institutionalization was evaluated in a 4-year longitudinal study.

METHOD

A total of 410 persons with the clinical diagnosis of AD completed annual clinical evaluations to assess cognitive impairment, functional limitations, delusions, hallucinations, depressive symptoms and physical aggression. Participation rates among survivors exceeded 90% for four follow-up evaluations with complete ascertainment of mortality and institutionalization. Time to institutionalization was evaluated using proportional hazards regression models in relation to time-varying clinical features.

RESULTS

In multivariate models, adjusted for demographic and social variables, four clinical features emerged as the predominant predictors of institutionalization: cognitive impairment level, physical aggression, hallucinations and depressive symptoms. These associations were virtually unchanged in analyses controlling for mortality.

CONCLUSIONS

Specific behavioral symptoms are important independent risk factors for institutionalization in persons with AD. Because behavioral symptoms are susceptible to therapy, efforts to modify or prevent these symptoms deserve careful consideration as a means to delay institutionalization for persons with this disease.

Dietary niacin and the risk of incident Alzheimer's disease and of cognitive decline

BACKGROUND

Dementia can be caused by severe niacin insufficiency, but it is unknown whether variation in intake of niacin in the usual diet is linked to neurodegenerative decline. We examined whether dietary intake of niacin was associated with incident Alzheimer's disease (AD) and cognitive decline in a large, prospective study.

METHODS

This study was conducted in 1993-2002 in a geographically defined Chicago community of 6158 residents aged 65 years and older. Nutrient intake was determined by food frequency questionnaire. Four cognitive tests were administered to all study participants at 3 year intervals in a 6 year follow up. A total of 3718 participants had dietary data and at least two cognitive assessments for analyses of cognitive change over a median 5.5 years. Clinical evaluations were performed on a stratified random sample of 815 participants initially unaffected by AD, and 131 participants were diagnosed with 4 year incident AD by standardised criteria.

RESULTS

Energy adjusted niacin intake had a protective effect on development of AD and cognitive decline. In a logistic regression model, relative risks (95% confidence intervals) for incident AD from lowest to highest quintiles of total niacin intake were: 1.0 (referent) 0.3 (0.1 to 0.6), 0.3 (0.1 to 0.7), 0.6 (0.3 to 1.3), and 0.3 (0.1 to 0.7) adjusted for age, sex, race, education, and ApoE e4 status. Niacin intake from foods was also inversely associated with AD (p for linear trend = 0.002 in the adjusted model). In an adjusted random effects model, higher food intake of niacin was associated with a slower annual rate of cognitive decline, by 0.019 standardised units (SU) per natural log increase in intake (mg) (p = 0.05). Stronger associations were observed in analyses that excluded participants with a history of cardiovascular disease (beta = 0.028 SU/year; p = 0.008), those with low baseline cognitive scores (beta = 0.023 SU/year; p = 0.02), or those with fewer than 12 years' education (beta = 0.035 SU/year; p = 0.002)

CONCLUSION

Dietary niacin may protect against AD and age related cognitive decline.

Blood pressure and late-life cognitive function change: A biracial longitudinal population study

OBJECTIVE

To examine the relation of blood pressure (BP) to subsequent decline in cognitive function among persons age 65 or over.

METHODS

All persons age 65 or over in a geographically defined community were invited to participate in a longitudinal study of problems of the elderly. Interviews were conducted in the participants' homes and included two BP measures and four tests of cognitive function. Follow-up interviews 3 and 6 years after baseline repeated the cognitive function tests. These analyses included 4,284 individuals who had baseline and at least one follow-up measure of cognitive function. The average of z scores of the individual cognitive function tests was used as a global measure of cognitive function.

RESULTS

In random effects analyses controlling for age, sex, education, and race, there was no significant linear association of either systolic or diastolic BP with 6-year change in global cognitive function score. There was no significant curvilinear association with systolic BP. In tests for a curvilinear association with diastolic BP, there was a suggestion of increased decline among those with low or high diastolic BP (p = 0.03 for the quadratic diastolic term). At baseline, 50% of participants took some type of medication affecting BP.

CONCLUSION

In this community population where BP treatment was common, there was no association of either high systolic or high diastolic BP at the beginning of the observation interval with 6-year cognitive decline.