A population-based longitudinal study of cognitive functioning in the menopausal transition

BACKGROUND

No longitudinal studies have tracked cognitive performance through the menopausal transition and thus the impact of the transition on cognition, independent of aging, is not known. The authors hypothesized that a decline in cognitive functioning occurs as women progress through the menopausal transition, independent of age, educational level, family income, ethnicity, and baseline self-perceived health.

METHOD

The authors began a population-based, longitudinal study in January 1996 with yearly follow-up interviews. This report includes follow-up through November 2001. The authors randomly selected African American and white women from a census of two contiguous Chicago communities. After screening for eligibility (age 42 to 52 years, premenopausal or early perimenopausal, no exogenous hormone use in the past 3 months, and no hysterectomy), 868 agreed to participate. Women who became pregnant, had a hysterectomy, or began using hormones were censored from that time onward. This study reports on 803 women for whom cognitive assessments were available. The authors assessed working memory (Digit Span Backward) and perceptual speed (Symbol Digit Modalities Test).

RESULTS

Contrary to the hypothesis, the authors found small but significant increases over time during the premenopausal and perimenopausal phases. This trend was not accounted for by chronological age, education, family income, ethnicity, or baseline self-perceived health.

CONCLUSIONS

Transition through menopause is not accompanied by a decline in working memory and perceptual speed.

Cognitive activity and cognitive decline in a biracial community population

BACKGROUND

Frequent participation in cognitively stimulating activities has been associated with reduced risk of AD in several prospective studies. However, the association of cognitive activity with cognitive decline, the principal manifestation of AD, is not well understood.

METHODS

More than 4,000 older residents of a geographically defined biracial community of Chicago were interviewed at approximately 3-year intervals for an average of 5.3 years. Each interview included administration of four cognitive function tests from which a previously established global measure was derived. At baseline, each person rated frequency of participation in cognitively stimulating activities (e.g., reading a magazine) from which a previously established composite measure of cognitive activity was derived.

RESULTS

Cognitive activity scores ranged from 1 to 5 (mean = 3.14, SD = 0.66), with higher scores indicating more frequent participation. More frequent cognitive activity was associated with reduced cognitive decline during follow-up. In a model that controlled for baseline level of cognition, age, sex, race, and education, a 1-point increase in cognitive activity score was associated with an approximately 19% decrease in annual rate of cognitive decline (p < 0.001). This effect remained when we controlled for depressive symptoms and chronic medical conditions (p < 0.001), and when we excluded persons with evidence of memory impairment at baseline (p < 0.001).

CONCLUSION

Frequent participation in cognitively stimulating activities is associated with reduced cognitive decline in older persons.

Cerebral infarctions and the likelihood of dementia from Alzheimer disease pathology

BACKGROUND

Alzheimer disease (AD) is the most common cause of dementia. The effect of cerebral infarctions on the likelihood of dementia from AD pathology is not well understood.

METHODS

The study included 153 deceased Catholic clergy who participated in the Religious Orders Study. Annual evaluations, including 19 tests of cognitive function, were performed to determine a diagnosis of dementia and level of cognitive abilities proximate to death. At autopsy, neuritic and diffuse plaques and neurofibrillary tangles were counted and combined into a standardized summary measure of AD pathology. Number, volume, side, and distribution of old macroscopic infarctions were recorded. Analyses included logistic and linear regression, adjusting for age, sex, and education.

RESULTS

The AD pathology score ranged from 0 to 2.93 units, and 54 persons had infarctions. There was no relationship between AD pathology and infarctions (r = 0.04, p = 0.56). Each unit of AD pathology increased the odds of dementia by 4.40-fold (95% CI = 2.33 to 8.32), and this was essentially unchanged after accounting for infarctions. The presence of one or more infarctions independently increased the odds of dementia by 2.80-fold (95% CI = 1.26 to 6.21). There was no interaction between AD pathology and infarctions to further increase the likelihood of dementia (p = 0.39). The number, size, and distribution of infarctions added to the odds of dementia but also did not show an interaction with AD pathology. Similar results were found in analyses with global cognitive function and five different cognitive systems.

CONCLUSION

Cerebral infarctions independently contribute to the likelihood of dementia but do not interact with AD pathology to increase the likelihood of dementia beyond their additive effect.

Premorbid proneness to distress and episodic memory impairment in Alzheimer's disease

BACKGROUND

Chronic stress has been associated with impaired episodic memory, but the association of premorbidly experienced distress with memory function in Alzheimer's disease is unknown.

OBJECTIVE

To investigate the link between proneness to distress and Alzheimer's disease.

METHODS

Participants were 363 persons with clinically diagnosed Alzheimer's disease. At baseline, a knowledgeable informant rated each person's premorbid personality (that is, before dementia onset) along five dimensions, one of which was the tendency to experience psychological distress. Participants underwent structured clinical evaluations at baseline and then annually for up to four years. Each evaluation included 17 cognitive tests from which previously established measures of episodic memory, visuoconstruction, repetition, and naming were derived.

RESULTS

In a series of random effects models adjusted for age, sex, and education, premorbid distress proneness was associated with baseline impairment in episodic memory but not with impairment in other cognitive domains, or with change in any cognitive domain. No other trait was related to baseline function or rate of decline in any cognitive domain.

CONCLUSIONS

The results suggest that premorbid proneness to experience psychological distress is related to level of impairment in episodic memory in persons with Alzheimer's disease, but neither distress proneness nor other personality traits are related to disease progression.

Proneness to psychological distress is associated with risk of Alzheimer's disease

BACKGROUND

Chronic stress is associated with hippocampal damage and impaired memory in animals and humans.

OBJECTIVE

To examine this relationship with clinical and pathologic data from the Religious Orders Study.

METHODS

Older Catholic clergy members underwent annual clinical evaluations, which included clinical classification of Alzheimer's disease (AD) and detailed cognitive function testing from which composite measures of global cognition and specific cognitive functions were derived. At the baseline evaluation, participants completed a measure of the tendency to experience psychological distress, a stable personality trait that served as an indicator of susceptibility to negative emotional states across the life span. More than 90% of participants who died underwent a uniform postmortem examination of the brain from which summary measures of AD pathology were derived. The association of distress proneness with incident AD and cognitive decline and with measures of AD pathology was examined in analyses adjusted for selected demographic and clinical variables.

RESULTS

During a mean of 4.9 years of follow-up, 140 persons developed AD. Those high in distress proneness (90th percentile) had twice the risk of developing AD than those low in distress proneness (10th percentile). Distress proneness was related to decline in episodic memory but not in other cognitive domains, with a >10-fold increase in episodic memory decline in those high in distress proneness compared with those low in the trait. Among those who died, however, distress proneness was not related to common measures of AD pathology.

CONCLUSION

Proneness to experience psychological distress is a risk factor for AD, an effect independent of AD pathologic markers such as cortical plaques and tangles.

Depressive symptoms and cognitive decline in a community population of older persons

BACKGROUND

An association between depressive symptoms and cognitive decline has been observed in selected cohorts of older people, but studies of defined populations have had conflicting results.

OBJECTIVE

To test whether the level of depressive symptoms predicted the rate of cognitive decline in a biracial community of older persons.

METHODS

4392 older people (88% of those eligible) from a defined community in Chicago completed two or three structured interviews at approximately three year intervals for an average of 5.3 years. At the baseline interview, the number of depressive symptoms was assessed with a 10 item version of the Center for Epidemiologic Studies Depression scale. Cognitive function was assessed at each interview with four performance tests, from which a previously established measure of global cognition was derived. Random effects models were used to assess change in cognition and its relation to depressive symptoms, controlling for age, sex, race, education, and baseline cognitive function.

RESULTS

Participants reported a median of one depressive symptom at baseline (interquartile range, 0 to 2). For each depressive symptom, the rate of cognitive decline increased by a mean of about 5%. Results were not substantially changed when persons with cognitive impairment at baseline were excluded, or when chronic illness or participation in cognitively stimulating activities was controlled, and the association was not modified by age, sex, race, or education.

CONCLUSIONS

The results suggest that depressive symptoms predict cognitive decline in old age.

Neonatal chest wall rigidity following the use of remifentanil for cesarean delivery in a patient with autoimmune hepatitis and thrombocytopenia

Remifentanil is a useful adjunct in general anesthesia for high-risk obstetric patients. It provides effective blunting of the rapid hemodynamic changes that may be associated with airway manipulation and surgical stimulation. There have been no previous reports of opioid-related rigidity in the neonate delivered by a parturient receiving intraoperative remifentanil. We present a case of short-lived neonatal rigidity and respiratory depression following remifentanil administration during cesarean section to a parturient with autoimmune hepatitis complicated by cirrhosis, esophageal varices and thrombocytopenia.

Rate of cognitive decline and mortality in Alzheimer’s disease

Background: Alzheimer’s disease (AD) is associated with increased mortality, but survival in those with the disease varies widely. It is uncertain how much of the variation in survival is due to individual differences in rate of disease progression.

Methods: During a 4-year period, 354 persons with AD underwent annual clinical evaluations that included administration of 17 cognitive function tests, from which global and specific measures of cognitive function were derived. A growth curve approach was used to assess individual rates of cognitive decline and proportional hazards models adjusted for age, sex, and education to examine the associations of baseline level of cognition and rate of cognitive decline with mortality.

Results: During the 4-year study period, 242 persons survived and 112 died. At baseline, the global measure of cognition ranged from −1.68 to 1.36 (mean = 0.03, SD = 0.57), with higher scores indicating better function. Baseline level of cognition was not related to mortality (p = 0.12). Global cognition declined an average of 0.56 unit/year, with substantial heterogeneity (SD = 0.41). To determine mortality risk, persons were divided into quartiles based on rate of cognitive decline and survival contrasted in the quartile with the least decline with survival in each remaining quartile, adjusting for baseline level of cognition. Compared with those with the least decline, risk of death was increased more than threefold in the subgroup with mild decline, more than fivefold in those with moderately rapid decline, and more than eightfold in those with the most rapid decline. Similar results were found after controlling for baseline health and disability and in analyses using specific cognitive function measures.

Conclusion: Mortality in AD is strongly associated with rate of cognitive decline.

Education modifies the relation of AD pathology to level of cognitive function in older persons

OBJECTIVE

To test the hypothesis that years of formal education modifies the relation of AD pathology to level of cognitive function.

METHODS

A total of 130 older Catholic clergy participating in the Religious Orders Study underwent annual cognitive function testing and brain autopsy at the time of death. Individual cognitive function tests were z-scored and averaged to yield a global measure of cognitive function and summary measures of five different cognitive abilities. Neuritic and diffuse plaques and neurofibrillary tangles were counted in separate 1 mm(2) areas of maximal density. Counts were converted to standard scores by dividing by their SD, and combined to yield a global AD pathology score and summary scores of each postmortem index. Linear regression was used to examine the relation of education and AD pathology scores to level of cognitive function proximate to death, controlling for age and sex. Subsequent analyses tested the interaction between education and each AD pathology score to determine whether education modified the relation of AD pathology to level of cognitive function. Additional analyses examined these associations on five specific cognitive abilities.

RESULTS

Both years of formal education (regression coefficient = 0.073, p = 0.0001) and the global AD pathology score (regression coefficient = -0.689, p < 0.0001) were related to level of cognitive function. When an interaction term between education and AD pathology was added to the model, the association between a unit of AD pathology and level of cognitive function was 0.088 (p = 0.0078) standard unit less for each year of education than the level predicted from the model without the interaction term. Whereas neuritic plaques, diffuse plaques, and neurofibrillary tangles were all strongly related to cognitive function, education only modified the relation of neuritic plaques (p = 0.002) and diffuse plaques (p = 0.03) to cognition, but not neurofibrillary tangles. In analyses examining five different cognitive abilities, the interaction between education and the neuritic plaque score was strongest for perceptual speed and weakest for episodic memory.

CONCLUSIONS

These data provide strong evidence that the relation between senile plaques and level of cognitive function differs by years of formal education.

Gender, cognitive decline, and risk of AD in older persons

BACKGROUND

Cross-sectional studies suggest gender differences in cognitive function and risk of AD in older persons. However, longitudinal studies comparing change in cognitive function and risk of AD in men and women have had mixed results. The authors investigated gender differences in rate of decline for different cognitive systems and for risk of developing AD.

METHODS

Participants were from the Religious Orders Study, a longitudinal, clinical-pathologic study of aging and AD in older Catholic nuns, priests, and brothers. Longitudinal data were available from 577 older women and 271 older men, who completed an average of 5.8 annual evaluations with more than 95% follow-up participation in survivors. The evaluations included 21 neuropsychological tests, from which summary measures of global cognitive function and 5 functional domains were formed, and clinical classification of AD.

RESULTS

Random effects models were used to analyze change in cognitive function, and proportional hazards models were used to assess risk of incident AD. On average, men and women declined in all abilities during the 8-year period but did not differ in annual rates of change in analyses that controlled for age, education, and initial level of cognitive function. Risk of incident AD did not differ between men and women. Furthermore, results were unchanged after controlling for possession of the apolipoprotein-epsilon4 allele. Duration of estrogen use was related to rate of global cognitive decline and visuospatial abilities in women but did not influence comparisons between men and women in cognitive decline.

CONCLUSIONS

The results suggest that patterns of cognitive decline and incidence of AD are similar in older men and women.

Terminal decline in cognitive function

BACKGROUND

Impending death is thought to be associated with age-related cognitive decline, but this association has not been well studied.

METHODS

Participants were 763 older Roman Catholic nuns, priests, and brothers without dementia at baseline. They completed an average of 5.6 annual evaluations (range 2 to 9), with >95% follow-up participation in survivors. Each evaluation included administration of 19 cognitive function tests from which previously established measures of global cognition (mean = 0.108, SD = 0.502) and specific cognitive functions were derived. In a series of change point random effects models, the average point before death when rate of cognitive decline changed was identified, and rates of cognitive decline before and after the optimal change point were estimated, controlling for the effects of age, sex, and education.

RESULTS

There were 122 deaths during the observation period. Those who died had lower global cognitive function at baseline than survivors (by 0.103 unit; p = 0.03), and beginning about 43 months before death, their annual rate of global cognitive decline sharply accelerated from an annual loss of 0.026 to 0.173 unit, a more than sixfold increase. Results were comparable in analyses that controlled for baseline health and disability. Terminal cognitive decline was evident in nearly all of those who died, but at highly variable rates. Remarkably little cognitive decline was evident in survivors. Decline in episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability also greatly increased about 3 to 6 years prior to death.

CONCLUSION

On average, cognitive decline sharply accelerates in the last years of life.

Relation of cerebral infarctions to dementia and cognitive function in older persons

BACKGROUND

Cerebral infarctions are common in older persons but their relationship with dementia and cognitive function remains controversial.

METHODS

Participants were 164 older Catholic nuns, priests, and brothers who underwent annual clinical evaluation and brain autopsy at death. The authors quantified number and volume of old cerebral infarctions on postmortem examination and determined the association with dementia and cognitive function proximate to death. Analyses controlled for age, sex, and education.

RESULTS

A total of 58 (35.4%) subjects had cerebral infarctions: 29 had one infarction and 29 had multiple infarctions. In logistic regression analyses, infarctions increased the odds of dementia twofold (OR 2.12; 95% CI 1.06 to 4.25). The odds of dementia increased by 2.67-fold for multiple infarctions (95% CI 1.08 to 6.61), whereas the odds of dementia with single infarctions increased by 69% (95% CI 0.70 to 4.09). In linear regression analyses, there was a trend for multiple infarctions to be associated with lower global cognitive scores (-0.44 standard units, p = 0.057). Multiple infarctions were related to perceptual speed, visuospatial skills, and working memory, but not to episodic or semantic memory. The authors found similar results with infarction volume. In secondary analyses, only infarctions that were clinically evident during life were associated with dementia and cognitive function.

CONCLUSION

Cerebral infarctions are associated with a twofold increase in odds of dementia. Odds are higher in persons with multiple, large, or clinically evident infarctions. In addition, cerebral infarctions do not affect all cognitive systems equally, showing the strongest association with perceptual speed and the weakest with episodic memory.

Apolipoprotein E epsilon4 allele, AD pathology, and the clinical expression of Alzheimer's disease

OBJECTIVE

To test the hypothesis that the APOE epsilon4 allele is associated with the clinical manifestations of AD through an association with the pathologic hallmarks of disease.

METHODS

Participants were older Catholic nuns, priests, and brothers who agreed to annual neurologic and neuropsychological evaluation for AD and other common neurologic conditions and brain autopsy at the time of death. There were 77 persons without dementia and 51 with probable AD; 38 participants had one or more epsilon4 alleles.

RESULTS

In logistic regression analyses, controlling for age, sex, and education, the epsilon4 allele was strongly associated with the likelihood of clinical AD (odds = 3.46, 95% CI = 1.44 to 8.33). However, controlling for the effect of AD pathology, the association of the epsilon allele with clinical AD was reduced by >50% and was no longer significant (odds = 1.58, 95% CI = 0.56 to 4.43). Similarly, in linear regression analyses, controlling for age, sex, and education, the epsilon4 allele was strongly associated with level of cognitive function proximate to death (regression coefficient = -0.477, p = 0.005). However, after controlling for the effect of AD pathology, the association of the epsilon4 allele with level of cognition was reduced by >80% and was no longer significant (regression coefficient = -0.093). Similar results were found in analyses using separate measures of neuritic plaques, diffuse plaques, and neurofibrillary tangles, and in analyses of five different cognitive systems (episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability).

CONCLUSIONS

The APOE epsilon4 allele appears to be associated with the clinical manifestations of AD through an association with the pathologic hallmarks of AD rather than another mechanism.

Cognitive activity and incident AD in a population-based sample of older persons

BACKGROUND

Participation in cognitively stimulating activities is hypothesized to be associated with risk of AD, but knowledge about this association is limited.

METHODS

A biracial community in Chicago was censused, persons aged 65 years and older were asked to participate in an interview, and 6,158 of 7,826 (79%) eligible persons did so. As part of the interview, persons rated current frequency of participation in seven cognitive activities (e.g., reading a newspaper) and nine physical activities (e.g., walking for exercise) from which composite measures of cognitive and physical activity frequency were derived. Four years later, 1,249 of those judged free of AD were sampled for a detailed clinical evaluation of incident disease and 842 (74% of those eligible) participated.

RESULTS

The composite measure of cognitive activity ranged from 1.28 to 4.71 (mean 3.30; SD 0.59), with higher scores indicating more frequent activity. A total of 139 persons met National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD on clinical evaluation. In a logistic regression model adjusted for age, education, sex, race, and possession of the APOE epsilon4 allele, a one-point increase in cognitive activity score was associated with a 64% reduction in risk of incident AD (OR 0.36; 95% CI 0.20 to 0.65). By contrast, weekly hours of physical activity (mean 3.5; SD 5.1) was not related to disease risk (OR 1.04; 95% CI 0.98 to 1.10). Education was associated with risk of AD and a similar trend was present for occupation, but these effects were substantially reduced when cognitive activity was added to the model.

CONCLUSION

Frequency of participation in cognitively stimulating activities appears to be associated with risk of AD and may partially explain the association of educational and occupational attainment with disease risk.

The apolipoprotein E epsilon 2 allele and decline in episodic memory

OBJECTIVES

The apolipoprotein E (apoE) epsilon 4 allele is related to decline in multiple cognitive domains, especially episodic memory, but the effect of the epsilon 2 allele on change in different forms of cognitive function has been difficult to establish.

METHODS

Participants are from the Religious Orders Study. At baseline, they were at least 65 years old and free of clinical evidence of dementia. For up to eight years, they underwent annual clinical evaluations that included detailed cognitive function assessment from which previously established summary measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability were derived. Growth curve models were used to assess change in each measure and its relation to apoE genotype, controlling for age, sex, education, and baseline level of cognition. Follow up data were available in 669 persons (98% of those eligible). We treated those with the epsilon 3/3 genotype as the reference group (n=425), which was contrasted with epsilon 2 ( epsilon 2/2, epsilon 2/3; n=86), and epsilon 4 ( epsilon 3/4, epsilon 4/4; n=158) subgroups.

RESULTS

Rate of episodic memory change in the three subgroups significantly differed, with an average annual increase of 0.016 units in the epsilon 2 subgroup and annual decreases of 0.022 units in those with epsilon 3/3 and of 0.073 units in the epsilon 4 subgroup. The epsilon 2 subgroup did not differ from those with epsilon 3/3 in rate of decline in other cognitive systems. The epsilon 4 subgroup declined more rapidly than those with epsilon 3/3 in semantic memory and perceptual speed but not in working memory or visuospatial ability.

CONCLUSION

Possession of one or more apoE epsilon 2 alleles is associated with reduced decline in episodic memory in older persons.

Depressive symptoms, cognitive decline, and risk of AD in older persons

BACKGROUND

Cross-sectional and retrospective case-control studies suggest an association of depression symptoms with cognitive impairment and AD, but there have been few prospective studies and their results have been inconsistent.

METHODS

Participants are Catholic clergy members who were aged > or =65 years and who did not have clinical evidence of AD. During a 7-year period, they underwent annual clinical evaluations that included clinical classification of AD and detailed cognitive function testing from which global and specific measures of cognition were derived. Number of depressive symptoms was assessed at baseline with a modified, 10-item Center for Epidemiologic Studies Depression Scale (CES-D). The association of CES-D score with incident AD, using proportional hazards models, and cognitive decline, using random effects models, was examined.

RESULTS

At baseline, participants reported an average of about one depressive symptom on the CES-D scale (range, 0 to 8). During the 7 years of follow-up, 108 persons developed AD. In analyses that controlled for selected demographic and clinical variables including baseline level of cognitive function, CES-D score was associated with both risk of AD and rate of cognitive decline. For each depressive symptom, risk of developing AD increased by an average of 19%, and annual decline on a global cognitive measure increased by an average of 24%.

CONCLUSIONS

The results raise the possibility that depressive symptoms in older persons may be associated with risk of developing AD.

Natural history of mild cognitive impairment in older persons

BACKGROUND

Cognitive abilities of older persons range from normal, to mild cognitive impairment, to dementia. Few large longitudinal studies have compared the natural history of mild cognitive impairment with similar persons without cognitive impairment.

METHODS

Participants were older Catholic clergy without dementia, 211 with mild cognitive impairment and 587 without cognitive impairment, who underwent annual clinical evaluation for AD and an assessment of different cognitive abilities. Cognitive performance tests were summarized to yield a composite measure of global cognitive function and separate summary measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability. The authors compared the risk of death, risk of incident AD, and rates of change in global cognition and different cognitive domains among persons with mild cognitive impairment to those without cognitive impairment. All models controlled for age, sex, and education.

RESULTS

On average, persons with mild cognitive impairment had significantly lower scores at baseline in all cognitive domains. Over an average of 4.5 years of follow-up, 30% of persons with mild cognitive impairment died, a rate 1.7 times higher than those without cognitive impairment (95% CI, 1.2 to 2.5). In addition, 64 (34%) persons with mild cognitive impairment developed AD, a rate 3.1 times higher than those without cognitive impairment (95% CI, 2.1 to 4.5). Finally, persons with mild cognitive impairment declined significantly faster on measures of episodic memory, semantic memory, and perceptual speed, but not on measures of working memory or visuospatial ability, as compared with persons without cognitive impairment.

CONCLUSIONS

Mild cognitive impairment is associated with an increased risk of death and incident AD, and a greater rate of decline in selected cognitive abilities.

Progression of gait disorder and rigidity and risk of death in older persons

BACKGROUND

Bradykinesia, gait disturbance, rigidity, and tremor are common motor signs in old age. All of these signs are associated with increased morbidity and mortality, but the extent to which they are progressive is unknown.

METHODS

Study participants were 787 older Catholic clergy members without clinically diagnosed PD, related conditions, or dementia at baseline. They were evaluated annually for up to 7 years, with >95% follow-up participation by survivors. Evaluations included administration of a modified version of the motor portion of the Unified PD Rating Scale (UPDRS), from which previously established measures of the global UPDRS and four specific motor signs were derived. Scores represent the percent of the total possible UPDRS score obtained.

RESULTS

At baseline, the global UPDRS score ranged from 0 to 36.3 (mean +/- SD, 7.3 +/- 6.4). It increased by an average of 0.69 unit per year during follow-up, with more rapid progression in older persons, but there was wide variability with no progression in 21% of subjects and annual increases of up to 8.23 units in the remaining 79%. Of 129 persons who died, 106 had follow-up UPDRS data. In a proportional hazards model, risk of death was associated with both the level of the global UPDRS score at baseline and the annual rate of progression (both p < 0.001). Overall, risk of death in subjects who had some worsening of the global UPDRS score was 2.93 times the rate among those without progression (95% CI, 1.32-6.50). Gait disorder/postural reflex impairment and rigidity worsened, but bradykinesia and tremor did not. Risk of death was associated with worsening of gait/posture but not with the other signs.

CONCLUSION

Gait disorder and rigidity, as assessed with the modified UPDRS, are usually progressive in old age. Both the severity of the gait disorder and its rate of progression are strongly associated with risk of death.

The effects of magnesium sulphate and EDTA in the hypercholesterolaemic rabbit

Numerous clinical reports suggest the beneficial effects of chelation therapy for the treatment of atherosclerosis. However, the results of these studies are inconclusive and controversial. The purpose of this present study was to examine the prophylactic and therapeutic effects of chelation liquid (CHL) in experimental atherosclerosis. Twenty New Zealand white rabbits were fed a 1% cholesterol-supplemented diet for 45 days. In the prophylactic phase of the study subcutaneous 300 mg EDTA + 500 mg magnesium sulphate (MgSO4) injections (five rabbits) and isotonic saline (five rabbits) were given to test and control groups, respectively, along with cholesterol rich diet. The CHL treatment ameliorated the rise of serum cholesterol and serum triglyceride concentrations, lowered serum calcium concentrations and reduced the aortic atheroma. In the therapeutic phase of the experiment the cholesterol diet was stopped and the remaining 10 animals were returned to normal diet. Five of these rabbits were given CHL injections and other five animals were given isotonic saline injections for 121 days. Although the level of cholesterol and triglyceride were not significantly different in the two groups, the serum calcium concentration and the percentage of the area of flate aortic specimen occupied by atheroma were significantly lower in the CHL treated rabbits as compared to controls. It is concluded that CHL injections have a definite prophylactic effect on atherogenesis in the cholesterol-fed rabbit, and may have some therapeutic value in the regression phase. Further confirmatory studies are suggested.

Mixed leishmanial infections in Rhombomys opimus: a key to the persistence of Leishmania major from one transmission season to the next

An important feature of the foci of zoonotic cutaneous leishmaniasis (ZCL) in Turkmenistan and Uzbekistan is a 6-10-month break in transmission when Leishmania parasites persist in great gerbils (Rhombomys opimus)--the main host for three species (L. major, L. turanica and L. gerbilli). Almost all (95%) of the laboratory-maintained R. opimus experimentally infected with L. major cured their infections within 6 months, a situation which, if mirrored in field conditions, cannot provide reliable persistence of the infection to the next transmission season. However, infections with L. turanica alone persisted for a mean of 15 months, and mixed infections of L. major and L. turanica persisted even longer (mean = 25 months), parasites of both species remaining detectable in the skin for at least 18 months. Isoenzyme identification of 664 isolates obtained from wild-caught R. opimus, and of 58 cloned strains developed from them, showed that L. turanica, which is non-pathogenic for humans, tends to predominate in the gerbils from all types of natural ZCL foci, including those which are hyper-endemic; in June, L. turanica may be present in 80%-100% of the R. opimus in the foci. In contrast, infections with L. major alone occur far less commonly, and are especially hard to find at the beginning of the transmission season. However, 5%-25% of great gerbils in these foci are each infected with a mixture of L. major and L. turanica. In hyper- and meso-endemic foci, the proportion of L. major within mixed infections of Leishmania increases significantly towards the end of transmission season (August-September). It would appear, therefore, that mixed L. major/L. turanica infections in R. opimus promote the persistence of L. major between transmission seasons.