The incidence of dementia in an Australian community population: the Sydney Older Persons Study

Measuring dementia incidence within a cohort of 267,153 older Australians using routinely collected linked administrative data

To estimate dementia incidence rates using Australian administrative datasets and compare the characteristics of people identified with dementia across different datasets. This data linkage study used a cohort of 267,153 from the Australian 45 and Up Study. Participants completed a survey in 2006-2009 and subsequent dementia was identified through pharmaceutical claims, hospitalisations, aged care eligibility assessments, care needs at residential aged care entry and death certificates. Age-specific, and age-standardised incidence rates, incidence rate ratios and survival from first dementia diagnosis were estimated. Estimated age-standardised dementia incidence rates using all linked datasets was 16.8 cases per 1000 person years for people aged 65+. Comparing incidence rates to the global published rates suggested 77% of cases were identified but this varied by age with highest coverage among those aged 80-84 years (92%). Incidence rate ratios were inconsistent across datasets for: sex, socio-economic disadvantage, size of support network, marital status, functional limitations and diabetes. Median survival from first dementia diagnosis ranged from 1.80 years in the care needs dataset to 3.74 years in the pharmaceutical claims dataset. Characteristics of people identified with dementia in different administrative datasets reflect the factors that drive interaction with specific services; this may introduce bias in observational studies using a single data-source to identify dementia.

Dementia in the oldest old: Beyond Alzheimer disease

In a Perspective, Aimee Pierce and Claudia Kawas discuss risk factors and pathologies of dementia in the oldest-old.

The Prevalence and Incidence of Dementia Due to Alzheimer's Disease: a Systematic Review and Meta-Analysis

BACKGROUND

Updated information on the epidemiology of dementia due to Alzheimer's disease (AD) is needed to ensure that adequate resources are available to meet current and future healthcare needs. We conducted a systematic review and meta-analysis of the incidence and prevalence of AD.

METHODS

The MEDLINE and EMBASE databases were searched from 1985 to 2012, as well as the reference lists of selected articles. Included articles had to provide an original population-based estimate for the incidence and/or prevalence of AD. Two individuals independently performed abstract and full-text reviews, data extraction and quality assessments. Random-effects models were employed to generate pooled estimates stratified by age, sex, diagnostic criteria, location (i.e., continent) and time (i.e., when the study was done).

RESULTS

Of 16,066 abstracts screened, 707 articles were selected for full-text review. A total of 119 studies met the inclusion criteria. In community settings, the overall point prevalence of dementia due to AD among individuals 60+ was 40.2 per 1000 persons (CI95%: 29.1-55.6), and pooled annual period prevalence was 30.4 per 1000 persons (CI95%: 15.6-59.1). In community settings, the overall pooled annual incidence proportion of dementia due to AD among individuals 60+ was 34.1 per 1000 persons (CI95%: 16.4-70.9), and the incidence rate was 15.8 per 1000 person-years (CI95%: 12.9-19.4). Estimates varied significantly with age, diagnostic criteria used and location (i.e., continent).

CONCLUSIONS

The burden of AD dementia is substantial. Significant gaps in our understanding of its epidemiology were identified, even in a high-income country such as Canada. Future studies should assess the impact of using such newer clinical diagnostic criteria for AD dementia such as those of the National Institute on Aging-Alzheimer's Association and/or incorporate validated biomarkers to confirm the presence of Alzheimer pathology to produce more precise estimates of the global burden of AD.

The Prevalence and Incidence of Dementia: a Systematic Review and Meta-analysis

Introduction

Dementia is a common neurological condition affecting many older individuals that leads to a loss of independence, diminished quality of life, premature mortality, caregiver burden and high levels of healthcare utilization and cost. This is an updated systematic review and meta-analysis of the worldwide prevalence and incidence of dementia.

Methods

The MEDLINE and EMBASE databases were searched for relevant studies published between 2000 (1985 for Canadian papers) and July of 2012. Papers selected for full-text review were included in the systematic review if they provided an original population-based estimate for the incidence and/or prevalence of dementia. The reference lists of included articles were also searched for additional studies. Two individuals independently performed abstract and full-text review, data extraction, and quality assessment of the papers. Random-effects models and/or meta-regression were used to generate pooled estimates by age, sex, setting (i.e., community, institution, both), diagnostic criteria utilized, location (i.e., continent) and year of data collection.

Results

Of 16,066 abstracts screened, 707 articles were selected for full-text review. A total of 160 studies met the inclusion criteria. Among individuals 60 and over residing in the community, the pooled point and annual period prevalence estimates of dementia were 48.62 (CI95%: 41.98-56.32) and 69.07 (CI95%: 52.36-91.11) per 1000 persons, respectively. The respective pooled incidence rate (same age and setting) was 17.18 (CI95%: 13.90-21.23) per 1000 person-years, while the annual incidence proportion was 52.85 (CI95%: 33.08-84.42) per 1,000 persons. Increasing participant age was associated with a higher dementia prevalence and incidence. Annual period prevalence was higher in North America than in South America, Europe and Asia (in order of decreasing period prevalence) and higher in institutional compared to community and combined settings. Sex, diagnostic criteria (except for incidence proportion) and year of data collection were not associated with statistically significant different estimates of prevalence or incidence, though estimates were consistently higher for females than males.

Conclusions

Dementia is a common neurological condition in older individuals. Significant gaps in knowledge about its epidemiology were identified, particularly with regard to the incidence of dementia in low- and middle-income countries. Accurate estimates of prevalence and incidence of dementia are needed to plan for the health and social services that will be required to deal with an aging population.

The Koori Growing Old Well Study: investigating aging and dementia in urban Aboriginal Australians

BACKGROUND

Dementia is an emerging health priority in Australian Aboriginal communities, but substantial gaps remain in our understanding of this issue, particularly for the large urban section of the population. In remote Aboriginal communities, high prevalence rates of dementia at relatively young ages have been reported. The current study is investigating aging, cognitive decline, and dementia in older urban/regional Aboriginal Australians.

METHODS

We partnered with five Aboriginal communities across the eastern Australian state of New South Wales, to undertake a census of all Aboriginal men and women aged 60 years and over residing in these communities. This was followed by a survey of the health, well-being, and life history of all consenting participants. Participants were also screened using three cognitive instruments. Those scoring below designated cut-offs, and a 20% random sample of those scoring above (i.e. "normal" range), completed a contact person interview (with a nominated family member) and medical assessment (blind to initial screening results), which formed the basis of "gold standard" clinical consensus determinations of cognitive impairment and dementia.

CONCLUSION

This paper details our protocol for a population-based study in collaboration with local Aboriginal community organizations. The study will provide the first available prevalence rates for dementia and cognitive impairment in a representative sample of urban Aboriginal people, across city and rural communities, where the majority of Aboriginal Australians live. It will also contribute to improved assessment of dementia and cognitive impairment and to the understanding of social determinants of successful aging, of international significance.

Diagnosing dementia in the oldest-old

The "oldest-old" comprise the fastest growing segment of the population in much of the world. Rates of dementia are extremely high in this age group and will present a major public health burden as the numbers of these individuals quadruple by the middle of the century. Studies in this age group are rare and frequently have small numbers of participants. In research studies and the clinic, the diagnosis of dementia and determination of the etiology of the disorder are challenging. In this review, we include some of our experiences in a population-based longitudinal investigation, The 90+ Study. Oldest-old individuals are more likely to suffer from medical comorbidities and have high rates of sensory loss, psychoactive medication usage, frailty and fatigue. Moreover, social and cultural expectations affect the reporting and interpretation of behavioral changes. These and other factors make it difficult to determine the relative contributions of cognitive losses and non-cognitive losses in the development of functional disability. Contributing further to the complexities of diagnosis, current research suggests that dementia in the oldest-old, compared to younger people, is more likely to be related to mixed disease pathologies. Frequent cerebral neuropathologies include Alzheimer's disease neurodegeneration, small and large vessel vascular disease, and hippocampal sclerosis. More research is necessary in the oldest-old to better understand the etiologies of dementia in this age group, and factors that may affect the expression of disease as we age.

The recognition of facial expressions of emotion in Alzheimer's disease: a review of findings

OBJECTIVE

To provide a selective review of the literature on the recognition of facial expressions of emotion in Alzheimer's disease (AD), to evaluate whether these patients show variation in their ability to recognise different emotions and whether any such impairments are instead because of a general decline in cognition.

METHODS

A narrative review based on relevant articles identified from PubMed and PsycInfo searches from 1987 to 2007 using keywords 'Alzheimer's', 'facial expression recognition', 'dementia' and 'emotion processing'.

CONCLUSION

Although the literature is as yet limited, with several methodological inconsistencies, AD patients show poorer recognition of facial expressions, with particular difficulty with sad expressions. It is unclear whether poorer performance reflects the general cognitive decline and/or verbal or spatial deficits associated with AD or whether the deficits reflect specific neuropathology. This under-represented field of study may help to extend our understanding of social functioning in AD. Future work requires more detailed analyses of ancillary cognitive measures, more ecologically valid facial displays of emotion and a reference situation that more closely approximates an actual social interaction.

Incidence of dementia and associated risk factors in Japan: The Osaki-Tajiri Project

The incidence of dementia and risk factors has not been fully investigated in Japan. Following a prevalence study in 1998, we investigated the incidence and associated factors in the same population in 2003 and 2005. Randomly selected 771 residents in Tajiri were targeted. The final participants included 204 (65.2%) healthy older adults (Clinical Dementia Rating, CDR 0) and 335 (73.1%) people with questionable dementia (CDR 0.5). We analyzed the incidence of dementia and dementing diseases, and possible risk factors. The risk factors included demographics, lifestyle-related factors, vascular risk factors, cognitive functions, and MRI findings. Overall, 3.9% of the CDR 0 and 37.0% of the CDR 0.5 participants developed dementia during the 5-year period, whereas 40.2% of the CDR 0.5 participants developed dementia during the 7-year period. Older adults had a higher incidence. Higher CDR Box scores had a higher incidence. Of the dementing diseases, 60.8% of participants developed Alzheimer' disease (AD), followed by vascular dementia (VaD), 17.9%. Logistic regression analyses showed that age, MMSE, cognitive functions such as recent memory, and generalized atrophy were significant predictors of progression to AD. Similarly, predictive factors for progression to VaD were age, MMSE, cognitive functions such as frontal function, and white matter lesions and cerebrovascular diseases. A comprehensive system including CDR, cognitive tests, and MRI, is recommended in community-based health policy planning.

Hippocampal size and dementia in stroke patients: the Sydney stroke study

BACKGROUND

Hippocampal atrophy is an early feature of Alzheimer's disease (AD) but it has also been reported in vascular dementia (VaD). It is uncertain whether hippocampal size can help differentiate the two disorders.

METHODS

We assessed 90 stroke/TIA patients 3-6 months after the event, and 75 control subjects, with neuropsychological tests, medical and psychiatric examination and brain MRI scans. A diagnosis of VaD, vascular mild cognitive impairment (VaMCI) or no cognitive impairment (NCI) was reached by consensus on agreed criteria. T1-weighted MRI was used to obtain total intracranial volume (TICV), gray and white matter volume, CSF volume, hippocampus and amygdala volumes, and T2-weighted scans for white matter hyperintensity (WMH) ratings.

RESULTS

Stroke/TIA patients had more white matter hyperintensities (WMHs), larger ventricle-to-brain ratios and smaller amygdalae than controls, but hippocampus size and gray and white matter volumes were not different. WMHs and amygdala but not hippocampal volume distinguished stroke/TIA patients with VaD and VaMCI and without NCI and amygdala volumes. Right hippocampus volume significantly correlated with new visual learning.

CONCLUSIONS

Stroke/TIA patients and patients with post-stroke VaMCI or mild VaD do not have hippocampal atrophy. The amygdala is smaller in stroke/TIA patients, especially in those with cognitive impairment, and this may be accounted for by white matter lesions. The hippocampus volume relates to episodic memory, especially right hippocampus and new visual learning. A longitudinal study of these subjects will determine whether hippocampal atrophy is a late development in VaD.

Substantia nigra echomorphology in the healthy very old: Correlation with motor slowing

Transcranial sonography reveals an increase in echogenicity in the substantia nigra of patients with idiopathic Parkinson's disease. Marked hyperechogenicity has also been described in 9% of the healthy population and is associated with subtle clinical or functional neuroimaging findings suggestive of changes in nigrostriatal function. It has therefore been hypothesised that a hyperechogenic substantia nigra represents an early stage of nigral degeneration or a predisposition for Parkinson's disease. In the present study, we correlated sonographic findings with motor and cognitive deficits in a group of healthy, very elderly subjects. Marked and moderately increased substantia nigra echogenicity was present in 25% and 21% of our healthy, very elderly subjects, respectively, and correlated strongly with the presence of extrapyramidal symptoms in the absence of cognitive deficits. The high incidence of substantia nigra hyperechogenicity measured in our very elderly subjects compared with previous TCS studies suggests that the prevalence of this feature increases with age and is consistent with the higher prevalence of Parkinson's disease in advanced age, as well as the increased frequency of extrapyramidal symptoms. Our results indicate that this simple technique can be used to identify and quantify brain changes associated with subtle motor dysfunction in the very elderly.

Impact of neuroprotection on incidence of Alzheimer's disease

Converging evidence suggests that high levels of education and intellectual activity increase the cognitive reserve and reduce the risk of dementia. However, little is known about the impact that different neuroprotective strategies may have on the incidence of Alzheimer's disease. Using a simple mathematical regression model, it is shown here that age-specific counts of basic cognitive units (surrogate of neurons or synapses) in the normal population can be estimated from Alzheimer's incidence rates. Hence, the model can be used to test the effect of neuroprotection on Alzheimer's incidence. It was found that the number of basic cognitive units decreases with age, but levels off in older people. There were no gender differences after correcting for survival. The model shows that even modest neuroprotective effects on basic cognitive units can lead to dramatic reductions in the number of Alzheimer's cases. Most remarkably, a 5% increase in the cognitive reserve would prevent one third of Alzheimer's cases. These results suggest that public health policies aimed at increasing the cognitive reserve in the general population (e.g., implementing higher levels of education) are likely the most effective strategy for preventing Alzheimer's disease.

Predicting memory performance in normal ageing using different measures of hippocampal size

A number of different methods have been employed to correct hippocampal volumes for individual variation in head size. Researchers have previously used qualitative visual inspection to gauge hippocampal atrophy. The purpose of this study was to determine the best measure(s) of hippocampal size for predicting memory functioning in 102 community-dwelling individuals over 80 years of age. Hippocampal size was estimated using magnetic resonance imaging (MRI) volumetry and qualitative visual assessment. Right and left hippocampal volumes were adjusted by three different estimates of head size: total intracranial volume (TICV), whole-brain volume including ventricles (WB+V) and a more refined measure of whole-brain volume with ventricles extracted (WB). We compared the relative efficacy of these three volumetric adjustment methods and visual ratings of hippocampal size in predicting memory performance using linear regression. All four measures of hippocampal size were significant predictors of memory performance. TICV-adjusted volumes performed most poorly in accounting for variance in memory scores. Hippocampal volumes adjusted by either measure of whole-brain volume performed equally well, although qualitative visual ratings of the hippocampus were at least as effective as the volumetric measures in predicting memory performance in community-dwelling individuals in the ninth or tenth decade of life.

Management of agitation, aggression, and psychosis associated with dementia: a pooled analysis including three randomized, placebo-controlled double-blind trials in nursing home residents treated with risperidone

This analysis used pooled data from three randomized, placebo-controlled trials that examined the efficacy and safety of risperidone for the treatment of agitation, aggression, and psychosis associated with dementia in elderly nursing home residents to assess the risk-benefit of the use of risperidone in this population. The efficacy data (risperidone n=722, placebo n=428) were obtained from the Cohen-Mansfield agitation inventory (CMAI) and behavioral pathology in Alzheimer's disease (BEHAVE-AD) total and subscales. Additionally, clinical global impression (CGI) assessments were performed. Subgroup analyses were performed by type of dementia, severity of dementia, presence or absence of somnolence as an adverse event, and presence or absence of psychosis at baseline. Safety assessments included evaluation of treatment emergent adverse events, Extrapyramidal Symptom Rating Scale, ECG and vital signs, and Mini-Mental State Examination (MMSE). The mean dose of risperidone at end point was 1.0 mg/day (0.02 S.E.). The observed mean change at end point was significantly higher for risperidone than for placebo on CMAI total score (-11.8 versus -6.4, respectively; p<0.001), total aggression score (-5.0 versus -1.8, respectively; p<0.001), BEHAVE-AD total score (-6.1 and -3.6, respectively; p<0.001), and psychotic symptoms score (-2.1 and -1.3, respectively; p=0.003). The main treatment effects of risperidone were similar in all subgroup analyses. Additionally, risperidone-treated patients scored significantly better than placebo-treated patients on the CGI scales at end point. The incidence of treatment-emergent adverse events was comparable between risperidone (84.3%) and placebo (83.9%). More patients discontinued due to adverse events in the risperidone-treated group (17.2%) than in the placebo group (11.2%). Differences in adverse event incidences between placebo and risperidone were observed for extrapyramidal symptoms (EPS), mild somnolence and the less common cerebrovascular adverse events (CAE). Risperidone induced neither orthostatic, nor anticholinergic side effects nor falls nor cognitive decline. Of all atypical antipsychotics, risperidone has the largest database of double-blind controlled trials to support its efficacy and safety in the treatment of agitation, aggression, and psychosis associated with dementia. At the recommended doses, risperidone displayed a favorable risk-benefit profile. Risperidone was well tolerated with respect to EPS, somnolence, and anticholinergic side effects in this elderly population. In view of the risk for CAEs, risperidone, should be targeted towards the treatment of those patients in whom psychotic and behavioral symptoms of dementia are prominent and associated with significant distress, functional impairment or danger to the patient.

Guardianship and financial management legislation: what doctors in aged care need to know

Demographic and epidemiological changes have resulted in increasing numbers of elderly people, and in increasing numbers of elderly people suffering from various degrees of cognitive impairment, including dementia. It is well recognized that the presence of cognitive impairment may impact upon an older person's decision-making capacity, which has, in turn, been associated with increased acknowledgement of the need for greater accessibility to methods by which substitute decision-makers are appointed. To this end, legislation has been enacted throughout Australia to enable the appointment of substitute decision-makers in the form of guardians and financial managers. Medical practitioners are the largest group of health professional whose opinion is sought when appointments are being considered. Despite the significance of the legislation to the evaluation of elderly people with impaired cognition, many health professionals remain unaware of the provisions of the legislation and are unclear about what information will be required. The aims of this review are first, to provide health professionals with the legal context within which their evaluations of disability and capacity take place, by way of a review of the relevant guardianship and financial management legislation in each of the states and territories of Australia; and second, to discuss how these provisions relate to existing clinical practice, with suggested guidelines for the capacity assessment. The focus and quality of information that health professionals provide will be enhanced by them having a greater understanding of their role within the wider legal context by placing in their hands knowledge of the provisions of the relevant legislation.

Incidence of Dementia in a Rural Community in Spain: The Girona Cohort Study

BACKGROUND

Information on dementia incidence in Spanish populations is still scarce, and there is a dearth of prospective studies.

OBJECTIVE

To estimate the incidence rates of dementia, Alzheimer's disease (AD) and vascular dementia (VaD) in a population cohort aged 75 and over in a rural area in Spain.

METHODS

A prospective population cohort study over a 5-year period in 8 rural villages in the province of Girona. The baseline study in 1990 identified 200 prevalent cases of dementia. The dementia-free cohort included 1,260 persons aged 75 and over. This was the sample used for the incidence study. We rescreened and selectively reexamined this group in 1995 using a two-phase procedure consisting of a screening interview at home using the MMSE. Diagnoses of dementia, AD and VaD were established using the Cambridge Examination for Mental Disorders of the Elderly for surviving participants. For deceased participants, we used the Retrospective Collateral Dementia Interview to establish a diagnosis of dementia and AD according to DSM-III-R diagnostic criteria.

RESULTS

Information was obtained for 91% of the subjects at risk; 122 incident cases of dementia were identified. Incidence rates per 1,000 person-years at risk were 23.2 (95% CI = 19.1-27.3) for dementia, 10.8 (95% CI = 7.8-13.7) for AD and 9.5 (95% CI = 6.7-12.1) for VaD. All dementia subtypes showed an age-dependent pattern. Females had a relative risk of 1.8 (95% CI = 1.0-3.4) to develop AD. The inclusion of deceased cases with manifestations of dementia increased the rate of dementia incidence in 7.1 cases/1,000 person-years at risk.

CONCLUSION

Incidence rates were similar to those reported by other cohort studies. All dementia subtypes increased with age, but incidence rates did not increase exponentially in the oldest old. Females were at increased risk for AD. The inclusion of information about dementia symptoms from relatives of deceased participants was useful in order to avoid underestimation of the dementia incidence rates. Underestimation of the incidence rates was more important in those aged 75-84 years.

Hippocampal size and memory function in the ninth and tenth decades of life: the Sydney Older Persons Study

OBJECTIVES

The purpose of this study was to define magnetic resonance imaging (MRI) correlates of normal brain ageing, with the specific objective of investigating whether the size of the hippocampus is selectively correlated with age related memory performance in non-demented individuals in their ninth and tenth decades of life.

METHODS

Hippocampal size was estimated using MRI based volumetry and qualitative visual assessment in 102 community dwelling individuals aged between 81 and 94 years. Participants were evaluated on a variety of clinical and experimental instruments, including a comprehensive neuropsychological test battery. All participants underwent neurological examination, an extensive medical history was obtained, and an informant confirmed details of each participant's functional ability.

RESULTS

Both visual and volumetric hippocampal measures were identified as robust predictors of memory performance, even when the influence of age related illnesses and sociodemographic variables was accounted for. When the sample was reduced to include the most cognitively healthy participants who were rated by an informant as showing no evidence of cognitive decline, the left hippocampal measures remained significant predictors of delayed retention of verbal material.

CONCLUSIONS

These findings suggest that hippocampal volumes are selectively correlated with memory functioning in both normal and successful ageing.

Are MRI white matter lesions clinically significant in the 'old-old'? Evidence from the Sydney Older Persons Study

BACKGROUND

The number of individuals aged over 80 years is the fastest increasing group in developed countries. White matter lesions (WML) observed on magnetic resonance imaging (MRI) have uncertain clinical significance, particularly in the old.

OBJECTIVES

To determine the prevalence of periventricular and deep WML in survivors of an original cohort of randomly selected elderly community dwellers, and to examine their associations with clinical markers of vascular and extrapyramidal disorders of ageing, as well as quantitative cognitive measures.

METHODS

Brain MRI, lifestyle interview, cognitive testing and medical examination were administered to 122 participants from the Sydney Older Persons Study 6-year review (mean age: 85.5 years). Apolipoprotein E (ApoE) genotype was also established. Presence and severity of periventricular and deep WML were ascertained using semi-quantitative rating methods and their relations to the cognitive and clinical variables investigated.

RESULTS

Periventricular WML were present in all participants in similar severity for all three regions sampled. In contrast, a gradient of severity was observed for the deep WML: most severe in the parietal region, followed by the frontal and occipital regions, and least severe in the temporal region. Associations with gender or with the ApoE epsilon4 allele were non-significant. WML were inconsistently associated with age and cognitive functioning or with the clinical markers of dementia. No frontal specificity emerged. Examination of individual lesion types did not change the general pattern of associations. Supporting evidence for a threshold effect was observed on some measures.

CONCLUSIONS

WML are extremely common in elderly, non-demented individuals. Unlike in younger individuals, MRI abnormalities may not be evidence of a current pathological process and their importance may change with advancing age.

Defining the role of the caregiver in Alzheimer's disease treatment

The day-to-day responsibility of caring for a person with dementia often exacts a toll upon the caregiver, which may be manifested psychologically, physically, socially and financially. The last decade has witnessed the advent of drug availability for the treatment of Alzheimer's disease, specifically the cholinesterase inhibitors. Caregivers are integral to the initiation, administration and monitoring of treatment. In particular, they provide substitute informed consent when patients are no longer competent to do so. While there is evidence that cholinesterase inhibitors may reduce caregiver burden and time spent assisting patients, there are also burdens associated with being the person responsible for administering medication. Caregivers are key to research into the use of medications for Alzheimer's disease. They have roles in recruitment and consent and monitoring response and adverse effects. Increasingly, caregivers themselves are recognised as legitimate targets for evaluating the efficacy of new pharmacological agents for Alzheimer's disease (as benefits have been demonstrated for them). Caregivers have responsibilities regarding the drug treatment of patients with Alzheimer's disease, and require information about the medications so that they can have realistic expectations. Doctors need to work in partnership with caregivers and patients when prescribing drugs for Alzheimer's disease.

Vascular risk factors, cognition and dementia incidence over 6 years in the Sydney Older Persons Study

The specific contributions of factors associated with an increased risk of stroke to cognitive decline and vascular dementia in elderly people remain somewhat unclear. We investigated the prevalence of vascular risk factors (RFs) and their role on the incidence of dementia, cognitive decline and death over a 6-year period in a sample of 377 non-demented community dwellers aged 75 years and over at the time of study entry. Presence and history of vascular RFs and cognitive decline over 6 years were ascertained using direct interviews, medical and cognitive examinations. Hypertension and history of heart disease were very common affecting about 50% of the participants. At 6 years, 114 (30%) participants had died, and 63 (16.7%) met diagnostic criteria for dementia. Hypertension was significantly associated with a greater cognitive decline but not with dementia. Smoking and stroke diagnosis showed a significant positive association with death. Reported hypercholesterolaemia was found to be associated with a protective effect for the development of dementia, for cognitive decline and for death over the 6-year period. All other associations were non-significant. Figures of dementia incidence are similar to previous studies in contrast to the lack of anticipated effects of the vascular RFs. The results indicate that in very old participants, the impact of vascular RFs changes with time and may no longer contribute to the development of dementia and cognitive decline.

Normal aging and executive functions in "old-old" community dwellers: poor performance is not an inevitable outcome

BACKGROUND

Studies on normal aging and cognitive functioning commonly describe early and more pronounced age-related changes in executive functions (EFs) compared to other cognitive abilities. Two of the three most common neurodegenerative disorders associated with aging (vascular dementia [VaD] and extrapyramidal [EP]-related dementia) show executive dysfunctions in their clinical presentation; and these cognitive deficits are not uncommon in the third one: Alzheimer's disease (AD).

METHODS

Nine EF tests (yielding 12 measures) were administered to 123 randomly selected community dwellers, aged 81 years and over, with the view to determine the effect of age on performance. Markers of AD, VaD, and EP-related dementia, as well as sociodemographic and psychological variables, were selected and their contribution to EF performance was investigated.

RESULTS

Multiple linear regression analyses revealed the greatest contribution to EF scores from the markers of AD and estimated IQ but not from the markers of VaD and EP-related dementia or from age.

CONCLUSIONS

These findings suggest that chronological age acts as a proxy variable mediating the impact of other factors such as subclinical signs of neurodegenerative disorders and that it has little independent contribution to make. They also indicate the importance of cognitive abilities supported by posterior cortical circuits in EF problem resolution. This study demonstrates that cognitive decline is not an ineluctable process that is associated with "normal" aging but rather represents, in many cases, a byproduct of neurodegenerative disorders, albeit themselves highly age-related.