The importance of impaired physical health and age in normal cognitive aging

Practice effects in cognitive assessments three years later in non-carriers but not in symptom-free mutation carriers of autosomal-dominant Alzheimer's disease: Exemplifying procedural learning and memory?

Practice effects (PEs) defined as an improvement of performance in cognition due to repeated assessments between sessions are well known in unimpaired individuals, while less is known about impaired cognition and particularly in latent brain disease as autosomal-dominant Alzheimer's disease. The purpose was to evaluate the general (across tests/domains) and domain-specific PE calculated as the annual rate of change (ARC) in relation to years to the estimated disease onset (YECO) and in four groups of AD: asymptomatic mutation carriers (aAD, n = 19), prodromal, i.e., symptomatic mutation carriers, criteria for AD diagnosis not fulfilled (pAD, n = 4) and mutation carriers diagnosed with AD (dAD, n = 6) as well as mutation non-carriers from the AD families serving as a healthy comparison group (HC, n = 35). Cognition was assessed at baseline and follow-up about 3 years later by 12 tests covering six domains. The aAD and HC groups were comparable at baseline in demographic characteristics (age, gender, and education), when they were in their early forties, while the pAD and dAD groups were older and cognitively impaired. The results on mean ARC for the four groups were significantly different, small, positive, and age-insensitive in the HC group, while ARC was negative and declined with time/disease advancement in AD. The differences between HC and aAD groups in mean ARC and domain-specific ARC were not significant, indicating a subtle PE in aAD in the early preclinical stage of AD. In the symptomatic stages of AD, there was no PE probably due to cognitive disease-related progression. PEs were the largest in the verbal domain in both the HC and aAD groups, indicating a relationship with cognitive vulnerability. The group-related difference in mean ARC was predominant in timekeeping tests. To conclude, the practice effect in over 3 years was suggested to be linked to procedural learning and memory.

The APOE ε4 Allele Affects Cognitive Functions Differently in Carriers of APP Mutations Compared to Carriers of PSEN1 Mutations in Autosomal-Dominant Alzheimer's Disease

Mounting evidence shows that the APOE ε4 allele interferes with cognition in sporadic Alzheimer’s disease. Less is known about APOE in autosomal-dominant Alzheimer’s disease (adAD). The present study explored the effects on cognition associated with the gene–gene interactions between the APOE gene and the APP and PSEN1 genes in adAD. This study includes mutation carriers (MC) and non-carriers (NC) from adAD families with mutations in APP (n = 28 and n = 25; MC and NC, respectively) and PSEN1 (n = 12 and n = 15; MC and NC, respectively) that represent the complete spectrum of disease: AD dementia (n = 8) and mild cognitive impairment (MCI, n = 15 and presymptomatic AD, n = 17). NC represented unimpaired normal aging. There was no significant difference in the distribution of APOE ε4 (absence vs. presence) between the APP vs. PSEN1 adAD genes and mutation status (MC vs. NC). However, episodic memory was significantly affected by the interaction between APOE and the APP vs. PSEN1 genes in MC. This was explained by favorable performance in the absence of APOE ε4 in PSEN1 compared to APP MC. Similar trends were seen in other cognitive functions. No significant associations between APOE ε4 and cognitive performance were obtained in NC. In conclusion, cognitive effects of APOE–adAD gene interaction were differentiated between the PSEN1 and APP mutation carriers, indicating epistasis.

Associations between childhood adversities and late-life cognitive function: Potential mechanisms

RATIONALE

Childhood adversity, which is related to negative cognitive consequences, is highly prevalent across the world. Nonetheless, there is still a scarcity of research on late-life cognitive function that accounted for multiple aspects of adverse events as well as the potential mediating mechanism of social context and individual's wellbeing in adulthood.

OBJECTIVE

This study aimed to investigate the relationship between childhood adversities and late-life cognitive function among the middle-aged and older Chinese population and to determine the mediating role of education attainment, marital status, financial status, and self-rated health in adulthood.

METHODS

We used three waves of data from China Health and Retirement Longitudinal Study from 2011 to 2015, which consisted of 23 807 participants aged 45 years and older. Generalized Estimating Equation and Structural Equation Model were applied to examine the association between childhood adversities and cognitive function (mental intactness and episodic memory) and the corresponding potential mechanisms.

RESULTS

Overall, 77.25%, 64.55%, 38.38%, and 15.03% of respondents experienced socioeconomic disadvantage, parental involved trauma, maladaptive parental trauma, and other trauma in childhood, respectively. Multivariate analyses suggest that all four types of childhood adversities were associated with a lower score of mental intactness and the first three were associated with episodic memory. A large proportion of the associations between childhood adversity and cognitive function was mainly mediated by education attainment, self-rated health and marital status in adulthood.

CONCLUSION

There are negative linkages between childhood adversities and cognitive function in the middle-aged and older Chinese population. Such associations were primarily functioning indirectly through adult social context and health conditions.

[18F]THK5317 imaging as a tool for predicting prospective cognitive decline in Alzheimer's disease

Cross-sectional studies have indicated potential for positron emission tomography (PET) in imaging tau pathology in Alzheimer's disease (AD); however, its prognostic utility remains unproven. In a longitudinal, multi-modal, prognostic study of cognitive decline, 20 patients with a clinical biomarker-based diagnosis in the AD spectrum (mild cognitive impairment or dementia and a positive amyloid-beta PET scan) were recruited from the Cognitive Clinic at Karolinska University Hospital. The participants underwent baseline neuropsychological assessment, PET imaging with [¹⁸F]THK5317, [¹¹C]PIB and [¹⁸F]FDG, magnetic resonance imaging, and in a subgroup cerebrospinal fluid (CSF) sampling, with clinical follow-up after a median 48 months (interquartile range = 32:56). In total, 11 patients declined cognitively over time, while 9 remained cognitively stable. The accuracy of baseline [¹⁸F]THK5317 binding in temporal areas was excellent at predicting future cognitive decline (area under the receiver operating curve 0.84-1.00) and the biomarker levels were strongly associated with the rate of cognitive decline (β estimate -33.67 to -31.02, p < 0.05). The predictive accuracy of the other baseline biomarkers was poor (area under the receiver operating curve 0.58-0.77) and their levels were not associated with the rate of cognitive decline (β estimate -4.64 to 15.78, p > 0.05). Baseline [¹⁸F]THK5317 binding and CSF tau levels were more strongly associated with the MMSE score at follow-up than at baseline (p < 0.05). These findings support a temporal dissociation between tau deposition and cognitive impairment, and suggest that [¹⁸F]THK5317 predicts future cognitive decline better than other biomarkers. The use of imaging markers for tau pathology could prove useful for clinical prognostic assessment and screening before inclusion in relevant clinical trials.

Longitudinal cognitive decline in autosomal-dominant Alzheimer's disease varies with mutations in APP and PSEN1 genes

The purpose was to compare longitudinal cognitive changes in APP and PSEN1 gene mutation carriers and noncarriers from four autosomal-dominant Alzheimer's disease (ADAD) families across preclinical and early clinical stages of disease. Carriers (n = 34) with four different mutations (PSEN1_M146V, PSEN1_H163Y, APP_SWE, and APP_ARC) and noncarriers (n = 41) were followed up longitudinally with repeated cognitive assessments starting many years before the expected clinical onset. The relationship between cognition and years to expected clinical onset, education, age, and type of mutation was analyzed using mixed-effects models. Results showed an education-dependent and time-related cognitive decline with linear and quadratic predictors in mutation carriers. Cognitive decline began close to the expected clinical onset and was relatively rapid afterward in PSEN1 mutation carriers, whereas decline was slower and started earlier than 10 years before expected clinical onset in APP mutation carriers. In noncarriers, the decline was minimal across time in accordance with normal aging. These results suggest that phenotypes for onset and rate of cognitive decline vary with PSEN1 and APP genes, suggesting a behavioral heterogeneity in ADAD.

Five-year change scores in old age for six neuropsychological tests and normative data for the Useful Field of View (UFOV) test: The influence of physical health

INTRODUCTION

Neuropsychological assessment of cognitive change over time is often conducted in clinical settings, but whether neuropsychological change scores are influenced by physical health has, as far as we know, not been examined previously.

METHOD

In a sample of 153 older Swedish adults (age range, 72-86 years), we evaluated the influence of common age-related diseases, terminal decline pathology, age, education, and gender, to provide (a) preliminary test-specific regression weights and 90% confidence intervals to assess significant change in performance after five years on tests of visual scanning, mental shifting, visual spatial ability, memory, reaction time, and selective attention, and (b) normative data for the Useful Field of View test (UFOV) from a single testing occasion.

RESULTS

Multiple regression analyses showed that test-retest changes were affected by physical health for mental shifting, visual spatial ability, memory, and reaction time, by age for mental shifting and visual reaction time, by education for visual spatial ability, and by Age × Education for auditory reaction time. Gender did not affect any of the change scores. The overall average of variance explained was 2.5%: up to 8.1% for physical health, 4.4% for age, and 3.6% for education. The UFOV scores were mostly influenced by age, but also by physical health and education.

CONCLUSIONS

The findings indicate that considering the influence of health on normative change scores in old age in addition to demographic factors leads to more accurate predictions of whether true change has occurred.

The association between singing and/or playing a musical instrument and cognitive functions in older adults

OBJECTIVES

Cognitive decline happens to everyone when aging, but to some more than others. Studies with children, adults, and professional musicians suggest that making music could be associated with better cognitive functioning. In older adults however, this association is less well investigated, which is therefore the aim of this study.

METHODS

In this cross-sectional study data from 1101 participants aged 64 and older from the Longitudinal Aging Study Amsterdam were used. Multivariable linear regression analyses were performed to test the association between making music and cognitive functioning and time spent making music and cognitive functioning. ANCOVA analyses were performed to differentiate between participants who made no music, only sang, only played an instrument or both sang and played an instrument in terms of cognitive functioning.

RESULTS

Making music was significantly positively associated with letter fluency, learning and attention/short-term memory. Time spent making music yielded no significant results. The ANCOVA analyses showed higher scores for participants who only played an instrument compared to participants who made no music on learning, working memory and processing speed. For processing speed the instrument only group also had a higher score than participants who only sang.

DISCUSSION

Making music at least once every two weeks and especially playing a musical instrument, is associated with better attention, episodic memory and executive functions. The results suggest that making music might be a potential protective factor for cognitive decline; however, to support this notion a longitudinal study design is needed.

Longitudinal changes of tau PET imaging in relation to hypometabolism in prodromal and Alzheimer's disease dementia

The development of tau-specific positron emission tomography (PET) tracers allows imaging in vivo the regional load of tau pathology in Alzheimer's disease (AD) and other tauopathies. Eighteen patients with baseline investigations enroled in a 17-month follow-up study, including 16 with AD (10 had mild cognitive impairment and a positive amyloid PET scan, that is, prodromal AD, and six had AD dementia) and two with corticobasal syndrome. All patients underwent PET scans with [¹⁸F]THK5317 (tau deposition) and [¹⁸F]FDG (glucose metabolism) at baseline and follow-up, neuropsychological assessment at baseline and follow-up and a scan with [¹¹C]PIB (amyloid-β deposition) at baseline only. At a group level, patients with AD (prodromal or dementia) showed unchanged [¹⁸F]THK5317 retention over time, in contrast to significant decreases in [¹⁸F]FDG uptake in temporoparietal areas. The pattern of changes in [¹⁸F]THK5317 retention was heterogeneous across all patients, with qualitative differences both between the two AD groups (prodromal and dementia) and among individual patients. High [¹⁸F]THK5317 retention was significantly associated over time with low episodic memory encoding scores, while low [¹⁸F]FDG uptake was significantly associated over time with both low global cognition and episodic memory encoding scores. Both patients with corticobasal syndrome had a negative [¹¹C]PIB scan, high [¹⁸F]THK5317 retention with a different regional distribution from that in AD, and a homogeneous pattern of increased [¹⁸F]THK5317 retention in the basal ganglia over time. These findings highlight the heterogeneous propagation of tau pathology among patients with symptomatic AD, in contrast to the homogeneous changes seen in glucose metabolism, which better tracked clinical progression.

Dual tracer tau PET imaging reveals different molecular targets for 11C-THK5351 and 11C-PBB3 in the Alzheimer brain

Purpose

Several tau PET tracers have been developed, but it remains unclear whether they bind to the same molecular target on the heterogeneous tau pathology. In this study we evaluated the binding of two chemically different tau-specific PET tracers (¹¹C-THK5351 and ¹¹C-PBB3) in a head-to-head, in vivo, multimodal design.

Methods

Nine patients with a diagnosis of mild cognitive impairment or probable Alzheimer’s disease and cerebrospinal fluid biomarker evidence supportive of the presence of Alzheimer’s disease brain pathology were recruited after thorough clinical assessment. All patients underwent imaging with the tau-specific PET tracers ¹¹C-THK5351 and ¹¹C-PBB3 on the same day, as well as imaging with the amyloid-beta-specific tracer ¹¹C-AZD2184, a T1-MRI sequence, and neuropsychological assessment.

Results

The load and regional distribution of binding differed between ¹¹C-THK5351 and ¹¹C-PBB3 with no statistically significant regional correlations observed between the tracers. The binding pattern of ¹¹C-PBB3, but not that of ¹¹C-THK5351, in the temporal lobe resembled that of ¹¹C-AZD2184, with strong correlations detected between ¹¹C-PBB3 and ¹¹C-AZD2184 in the temporal and occipital lobes. Global cognition correlated more closely with ¹¹C-THK5351 than with ¹¹C-PBB3 binding. Similarly, cerebrospinal fluid tau measures and entorhinal cortex thickness were more closely correlated with ¹¹C-THK5351 than with ¹¹C-PBB3 binding.

Conclusion

This research suggests different molecular targets for these tracers; while ¹¹C-PBB3 appeared to preferentially bind to tau deposits with a close spatial relationship to amyloid-beta, the binding pattern of ¹¹C-THK5351 fitted the expected distribution of tau pathology in Alzheimer’s disease better and was more closely related to downstream disease markers.

Electronic supplementary material

The online version of this article (10.1007/s00259-018-4012-5) contains supplementary material, which is available to authorized users.

Reduced penetrance of the PSEN1 H163Y autosomal dominant Alzheimer mutation: a 22-year follow-up study

Background

The range of onset ages within some PSEN1 families is wide, and a few cases of reduced penetrance of PSEN1 mutations have been reported. However, published data on reduced penetrance have been limited to clinical histories, often collected retrospectively and lacking biomarker information. We present a case of reduced penetrance of the PSEN1 H163Y mutation in a carrier prospectively followed for 22 years.

Methods

Two brothers (A and B), both carriers of the H163Y mutation, were followed between 1995 and 2017. They underwent repeated clinical evaluations, neuropsychological assessments, and cerebrospinal fluid analyses, as well as brain imaging examinations with structural magnetic resonance, [¹⁸F]fluorodeoxyglucose positron emission tomography, and [¹¹C]Pittsburgh compound B positron emission tomography.

Results

Brother A was followed between 44 and 64 years of age. Cognitive symptoms due to Alzheimer’s disease set in at the age of 54. Gradual worsening of symptoms resulted in admittance to a nursing home owing to dependence on others for all activities of daily living. He showed a curvilinear decline in cognitive function on neuropsychological tests, and changes on magnetic resonance imaging, positron emission tomography, and biomarkers in the cerebrospinal fluid supported a clinical diagnosis of Alzheimer’s disease. Brother A died at the age of 64 and fulfilled the criteria for definitive Alzheimer’s disease according to neuropathological examination results. Brother B was followed between the ages of 43 and 65 and showed no cognitive deterioration on repeated neuropsychological test occasions. In addition, no biomarker evidence of Alzheimer’s disease pathology was detected, either on imaging examinations or in cerebrospinal fluid.

Conclusions

The average (SD) age of symptom onset for PSEN1 H163Y is 51 ± 7 years according to previous studies. However, we present a case of a biomarker-verified reduction in penetrance in a mutation carrier who was still symptom-free at the age of 65. This suggests that other genetic, epigenetic, and/or environmental factors modify the onset age.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0374-y) contains supplementary material, which is available to authorized users.

A Cross-Validation of FDG- and Amyloid-PET Biomarkers in Mild Cognitive Impairment for the Risk Prediction to Dementia due to Alzheimer's Disease in a Clinical Setting

Assessments of brain glucose metabolism (18F-FDG-PET) and cerebral amyloid burden (11C-PiB-PET) in mild cognitive impairment (MCI) have shown highly variable performances when adopted to predict progression to dementia due to Alzheimer's disease (ADD). This study investigates, in a clinical setting, the separate and combined values of 18F-FDG-PET and 11C-PiB-PET in ADD conversion prediction with optimized data analysis procedures. Respectively, we investigate the accuracy of an optimized SPM analysis for 18F-FDG-PET and of standardized uptake value ratio semiquantification for 11C-PiB-PET in predicting ADD conversion in 30 MCI subjects (age 63.57±7.78 years). Fourteen subjects converted to ADD during the follow-up (median 26.5 months, inter-quartile range 30 months). Receiver operating characteristic analyses showed an area under the curve (AUC) of 0.89 and of 0.81 for, respectively, 18F-FDG-PET and 11C-PiB-PET. 18F-FDG-PET, compared to 11C-PiB-PET, showed higher specificity (1.00 versus 0.62, respectively), but lower sensitivity (0.79 versus 1.00). Combining the biomarkers improved classification accuracy (AUC = 0.96). During the follow-up time, all the MCI subjects positive for both PET biomarkers converted to ADD, whereas all the subjects negative for both remained stable. The difference in survival distributions was confirmed by a log-rank test (p = 0.002). These results indicate a very high accuracy in predicting MCI to ADD conversion of both 18F-FDG-PET and 11C-PiB-PET imaging, the former showing optimal performance based on the SPM optimized parametric assessment. Measures of brain glucose metabolism and amyloid load represent extremely powerful diagnostic and prognostic biomarkers with complementary roles in prodromal dementia phase, particularly when tailored to individual cases in clinical settings.

Amyloid β-associated cognitive decline in the absence of clinical disease progression and systemic illness

Introduction

High levels of amyloid β (Aβ) are associated with cognitive decline in cognitively normal (CN) older adults. This study investigated the nature of cognitive decline in healthy individuals who did not progress to mild cognitive impairment or dementia.

Method

Cognition was measured over 72 months and compared between low (Aβ−) and high (Aβ+) CN older adults (n = 335) who did not progress to mild cognitive impairment or dementia and who remained free of severe or uncontrolled systemic illness.

Results

Compared to the Aβ− group, the Aβ+ group showed no cognitive impairment at baseline but showed substantial decline in verbal learning, episodic memory, and attention over 72 months.

Discussion

Moderate cognitive decline, particularly for learning and memory, was associated with Aβ+ in CN older adults in the absence of clinical disease progression and uncontrolled or serious comorbid illness.

Selective impact of disease on short-term and long-term components of self-reported memory: a population-based HUNT study

BACKGROUND

Subjective memory is commonly considered to be a unidimensional measure. However, theories of performance-based memory suggest that subjective memory could be divided into more than one dimension.

OBJECTIVE

To divide subjective memory into theoretically related components of memory and explore the relationship to disease.

METHODS

In this study, various aspects of self-reported memory were studied with respect to demographics and diseases in the third wave of the HUNT epidemiological study in middle Norway. The study included all individuals 55 years of age or older, who responded to a nine-item questionnaire on subjective memory and questionnaires on health (n=18 633).

RESULTS

A principle component analysis of the memory items resulted in two memory components; the criterion used was an eigenvalue above 1, which accounted for 54% of the total variance. The components were interpreted as long-term memory (LTM; the first component; 43% of the total variance) and short-term memory (STM; the second component; 11% of the total variance). Memory impairment was significantly related to all diseases (except Bechterew's disease), most strongly to brain infarction, heart failure, diabetes, cancer, chronic obstructive pulmonary disease and whiplash. For most diseases, the STM component was more affected than the LTM component; however, in cancer, the opposite pattern was seen.

CONCLUSIONS

Subjective memory impairment as measured in HUNT contained two components, which were differentially associated with diseases.

Predicting Cognitive Decline across Four Decades in Mutation Carriers and Non-carriers in Autosomal-Dominant Alzheimer's Disease

OBJECTIVES

The aim of this study was to investigate cognitive performance including preclinical and clinical disease course in carriers and non-carriers of autosomal-dominant Alzheimer's disease (adAD) in relation to multiple predictors, that is, linear and non-linear estimates of years to expected clinical onset of disease, years of education and age.

METHODS

Participants from five families with early-onset autosomal-dominant mutations (Swedish and Arctic APP, PSEN1 M146V, H163Y, and I143T) included 35 carriers (28 without dementia and 7 with) and 44 non-carriers. All participants underwent a comprehensive clinical evaluation, including neuropsychological assessment at the Memory Clinic, Karolinska University Hospital at Huddinge, Stockholm, Sweden. The time span of disease course covered four decades of the preclinical and clinical stages of dementia. Neuropsychological tests were used to assess premorbid and current global cognition, verbal and visuospatial functions, short-term and episodic memory, attention, and executive function.

RESULTS

In carriers, the time-related curvilinear trajectory of cognitive function across disease stages was best fitted to a formulae with three predictors: years to expected clinical onset (linear and curvilinear components), and years of education. In non-carriers, the change was minimal and best predicted by two predictors: education and age. The trajectories for carriers and non-carriers began to diverge approximately 10 years before the expected clinical onset in episodic memory, executive function, and visuospatial function.

CONCLUSIONS

The curvilinear trajectory of cognitive functions across disease stages was mimicked by three predictors in carriers. In episodic memory, executive and visuospatial functions, the point of diverging trajectories occurred approximately 10 years ahead of the clinical onset compared to non-carriers. (JINS, 2017, 23, 195-203).

Imaging in-vivo tau pathology in Alzheimer's disease with THK5317 PET in a multimodal paradigm

Purpose

The aim of this study was to explore the cerebral distribution of the tau-specific PET tracer [¹⁸F]THK5317 (also known as (S)-[¹⁸F]THK5117) retention in different stages of Alzheimer’s disease; and study any associations with markers of hypometabolism and amyloid-beta deposition.

Methods

Thirty-three individuals were enrolled, including nine patients with Alzheimer’s disease dementia, thirteen with mild cognitive impairment (MCI), two with non-Alzheimer’s disease dementia, and nine healthy controls (five young and four elderly). In a multi-tracer PET design [¹⁸F]THK5317, [¹¹C] Pittsburgh compound B ([¹¹C]PIB), and [¹⁸F]FDG were used to assess tau pathology, amyloid-beta deposition and cerebral glucose metabolism, respectively. The MCI patients were further divided into MCI [¹¹C]PIB-positive (n = 11) and MCI [¹¹C]PIB-negative (n = 2) groups.

Results

Test-retest variability for [¹⁸F]THK5317-PET was very low (1.17–3.81 %), as shown by retesting five patients. The patients with prodromal (MCI [¹¹C]PIB-positive) and dementia-stage Alzheimer’s disease had significantly higher [¹⁸F]THK5317 retention than healthy controls (p = 0.002 and p = 0.001, respectively) in areas exceeding limbic regions, and their discrimination from this control group (using the area under the curve) was >98 %. Focal negative correlations between [¹⁸F]THK5317 retention and [¹⁸F]FDG uptake were observed mainly in the frontal cortex, and focal positive correlations were found between [¹⁸F]THK5317 and [¹¹C]PIB retentions isocortically. One patient with corticobasal degeneration syndrome and one with progressive supranuclear palsy showed no [¹¹C]PIB but high [¹⁸F]THK5317 retentions with a different regional distribution from that in Alzheimer’s disease patients.

Conclusions

The tau-specific PET tracer [¹⁸F]THK5317 images in vivo the expected regional distribution of tau pathology. This distribution contrasts with the different patterns of hypometabolism and amyloid-beta deposition.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-016-3363-z) contains supplementary material, which is available to authorized users.

Early astrocytosis in autosomal dominant Alzheimer's disease measured in vivo by multi-tracer positron emission tomography

Studying autosomal dominant Alzheimer's disease (ADAD), caused by gene mutations yielding nearly complete penetrance and a distinct age of symptom onset, allows investigation of presymptomatic pathological processes that can identify a therapeutic window for disease-modifying therapies. Astrocyte activation may occur in presymptomatic Alzheimer's disease (AD) because reactive astrocytes surround β-amyloid (Aβ) plaques in autopsy brain tissue. Positron emission tomography was performed to investigate fibrillar Aβ, astrocytosis and cerebral glucose metabolism with the radiotracers (11)C-Pittsburgh compound-B (PIB), (11)C-deuterium-L-deprenyl (DED) and (18)F-fluorodeoxyglucose (FDG) respectively in presymptomatic and symptomatic ADAD participants (n = 21), patients with mild cognitive impairment (n = 11) and sporadic AD (n = 7). Multivariate analysis using the combined data from all radiotracers clearly separated the different groups along the first and second principal components according to increased PIB retention/decreased FDG uptake (component 1) and increased DED binding (component 2). Presymptomatic ADAD mutation carriers showed significantly higher PIB retention than non-carriers in all brain regions except the hippocampus. DED binding was highest in presymptomatic ADAD mutation carriers. This suggests that non-fibrillar Aβ or early stage plaque depostion might interact with inflammatory responses indicating astrocytosis as an early contributory driving force in AD pathology. The novelty of this finding will be investigated in longitudinal follow-up studies.

Examining age-related shared variance between face cognition, vision, and self-reported physical health: a test of the common cause hypothesis for social cognition

The shared decline in cognitive abilities, sensory functions (e.g., vision and hearing), and physical health with increasing age is well documented with some research attributing this shared age-related decline to a single common cause (e.g., aging brain). We evaluate the extent to which the common cause hypothesis predicts associations between vision and physical health with social cognition abilities specifically face perception and face memory. Based on a sample of 443 adults (17–88 years old), we test a series of structural equation models, including Multiple Indicator Multiple Cause (MIMIC) models, and estimate the extent to which vision and self-reported physical health are related to face perception and face memory through a common factor, before and after controlling for their fluid cognitive component and the linear effects of age. Results suggest significant shared variance amongst these constructs, with a common factor explaining some, but not all, of the shared age-related variance. Also, we found that the relations of face perception, but not face memory, with vision and physical health could be completely explained by fluid cognition. Overall, results suggest that a single common cause explains most, but not all age-related shared variance with domain specific aging mechanisms evident.

The Association of Leisure Activities in Middle Adulthood with Cognitive Performance in Old Age: The Moderating Role of Educational Level

BACKGROUND

One of the fundamental challenges for gerontological research is how to maintain and promote intact cognitive functioning in old age. Previous research revealed that high educational level, good health status, and an active lifestyle during adulthood seem to be protective against cognitive impairment in old age. However, up to now, a detailed examination of the interaction of these relations based on a broader variety of activities and considering past and current activities is missing.

OBJECTIVE

The present study set out to extend the literature by investigating in more detail the interactions of educational level and health status with a broad variety of past and current leisure activities in their association with cognitive functioning in a large sample of older adults with a wide age range.

METHODS

A total of 2,812 older adults (aged 65-101 years) served as the sample for the present study. A test on verbal abilities and one on processing speed were applied. In addition, individuals were retrospectively interviewed regarding their educational level, current general health status, and 18 leisure activities (in terms of currently performed activities and those that had been carried out at the age of 45 years).

RESULTS

Regressions indicated that engaging in more current activities and in more activities at the age of 45 years (both analyzed as an overall activity measure) was related to better cognitive performance in old age (r values up to 0.39, p values <0.001). These associations were more pronounced in individuals with a low (compared to a high) educational level.

CONCLUSION

Present results suggest that an active lifestyle during middle adulthood may be related to better cognitive functioning in old age, particularly in individuals with a low educational level. These findings are discussed with respect to models of cognitive aging.

Degree of abnormality is associated with rate of change in measures of beta-amyloid, glucose metabolism and cognition in an autopsy-verified Alzheimer's disease case

The degree of abnormality and rate of change in cognitive functions, positron emission tomography Pittsburg compound B (PET PIB), and fluorodeoxyglucose (FDG) measures were studied for 8 years in an autopsy-confirmed Alzheimer's disease (AD) patient, who died 61 years old (Mini-Mental State Examination (MMSE) score 7). At first encounter with medical care, the patient was very mildly demented (MMSE score 27). She had four cognitive assessments and two examinations with PET PIB and FDG in 23 bilateral brain regions. The onset of cognitive decline was retrospectively estimated to have started in the early forties. The degree of impairment was inversely related to the rate of decline. A similar relationship was seen between the rate of change and the level of abnormality in both PIB and FDG. To conclude, rate of change in cognition, PIB, and FDG was associated with the degree of abnormality.

BioAge: toward a multi-determined, mechanistic account of cognitive aging

The search for reliable early indicators of age-related cognitive decline represents a critical avenue for progress in aging research. Chronological age is a commonly used developmental index; however, it offers little insight into the mechanisms underlying cognitive decline. In contrast, biological age (BioAge), reflecting the vitality of essential biological systems, represents a promising operationalization of developmental time. Current BioAge models have successfully predicted age-related cognitive deficits. Research on aging-related cognitive function indicates that the interaction of multiple risk and protective factors across the human lifespan confers individual risk for late-life cognitive decline, implicating a multi-causal explanation. In this review, we explore current BioAge models, describe three broad yet pathologically relevant biological processes linked to cognitive decline, and propose a novel operationalization of BioAge accounting for both moderating and causal mechanisms of cognitive decline and dementia. We argue that a multivariate and mechanistic BioAge approach will lead to a greater understanding of disease pathology as well as more accurate prediction and early identification of late-life cognitive decline.

Astrocytosis measured by ¹¹C-deprenyl PET correlates with decrease in gray matter density in the parahippocampus of prodromal Alzheimer's patients

PURPOSE

The Alzheimer's disease (AD) pathology is characterized by fibrillar amyloid deposits and neurofibrillary tangles, as well as the activation of astrocytosis, microglia activation, atrophy, dysfunctional synapse, and cognitive impairments. The aim of this study was to test the hypothesis that astrocytosis is correlated with reduced gray matter density in prodromal AD.

METHODS

Twenty patients with AD or mild cognitive impairment (MCI) underwent multi-tracer positron emission tomography (PET) studies with (11)C-Pittsburgh compound B ((11)C-PIB), (18) F-Fluorodeoxyglucose ((18) F-FDG), and (11)C-deuterium-L-deprenyl ((11)C-DED) PET imaging, as well as magnetic resonance imaging (MRI) scanning, cerebrospinal fluid (CSF) biomarker analysis, and neuropsychological assessments. The parahippocampus was selected as a region of interest, and each value was calculated for four different imaging modalities. Correlation analysis was applied between DED slope values and gray matter (GM) densities by MRI. To further explore possible relationships, correlation analyses were performed between the different variables, including the CSF biomarker.

RESULTS

A significant negative correlation was obtained between DED slope values and GM density in the parahippocampus in PIB-positive (PIB + ve) MCI patients (p = 0.025) (prodromal AD). Furthermore, in exploratory analyses, a positive correlation was observed between PIB-PET retention and DED binding in AD patients (p = 0.014), and a negative correlation was observed between PIB retention and CSF Aβ42 levels in MCI patients (p = 0.021), while the GM density and CSF total tau levels were negatively correlated in both PIB + ve MCI (p = 0.002) and MCI patients (p = 0.001). No significant correlation was observed with FDG-PET and with any of the other PET, MRI, or CSF biomarkers.

CONCLUSIONS

High astrocytosis levels in the parahippocampus of PIB + ve MCI (prodromal AD) patients suggest an early preclinical influence on cellular tissue loss. The lack of correlation between astrocytosis and CSF tau levels, and a positive correlation between astrocytosis and fibrillar amyloid deposition in clinical demented AD together indicate that parahippocampal astrocytosis might have some causality within the amyloid pathology.

The effect of age on fluid intelligence is fully mediated by physical health

The present study investigated the extent to which the effect of age on cognitive ability is predicted by individual differences in physical health. The sample consisted of 118 volunteer subjects who were healthy and ranging in age from 26 to 91. The examinations included a clinical investigation, magnetic resonance imaging (MRI) brain neuroimaging, and a comprehensive neuropsychological assessment. The effect of age on fluid IQ with and without visual spatial praxis and on crystallized IQ was tested whether being fully-, partially- or non-mediated by physical health. Structural equation analyses showed that the best and most parsimonious fit to the data was provided by models that were fully mediated for fluid IQ without praxis, non-mediated for crystallized IQ and partially mediated for fluid IQ with praxis. The diseases of the circulatory and nervous systems were the major mediators. It was concluded from the pattern of findings that the effect of age on fluid intelligence is fully mediated by physical health, while crystallized intelligence is non-mediated and visual spatial praxis is partially mediated, influenced mainly by direct effects of age. Our findings imply that improving health by acting against the common age-related circulatory- and nervous system diseases and risk factors will oppose the decline in fluid intelligence with age.

Evidence for astrocytosis in prodromal Alzheimer disease provided by 11C-deuterium-L-deprenyl: a multitracer PET paradigm combining 11C-Pittsburgh compound B and 18F-FDG

Astrocytes colocalize with fibrillar amyloid-β (Aβ) plaques in postmortem Alzheimer disease (AD) brain tissue. It is therefore of great interest to develop a PET tracer for visualizing astrocytes in vivo, enabling the study of the regional distribution of both astrocytes and fibrillar Aβ. A multitracer PET investigation was conducted for patients with mild cognitive impairment (MCI), patients with mild AD, and healthy controls using (11)C-deuterium-L-deprenyl ((11)C-DED) to measure monoamine oxidase B located in astrocytes. Along with (11)C-DED PET, (11)C-Pittsburgh compound B ((11)C-PIB; fibrillar Aβ deposition), (18)F-FDG (glucose metabolism), T1 MRI, cerebrospinal fluid, and neuropsychologic data were acquired from the patients.

METHODS

(11)C-DED PET was performed in MCI patients (n = 8; mean age ± SD, 62.6 ± 7.5 y; mean Mini Mental State Examination, 27.5 ± 2.1), AD patients (n = 7; mean age, 65.1 ± 6.3 y; mean Mini Mental State Examination, 24.4 ± 5.7), and healthy age-matched controls (n = 14; mean age, 64.7 ± 3.6 y). A modified reference Patlak model, with cerebellar gray matter as a reference, was chosen for kinetic analysis of the (11)C-DED data. (11)C-DED data from 20 to 60 min were analyzed using a digital brain atlas. Mean regional (18)F-FDG uptake and (11)C-PIB retention were calculated for each patient, with cerebellar gray matter as a reference.

RESULTS

ANOVA analysis of the regional (11)C-DED binding data revealed a significant group effect in the bilateral frontal and bilateral parietal cortices related to increased binding in the MCI patients. All patients, except 3 with MCI, showed high (11)C-PIB retention. Increased (11)C-DED binding in most cortical and subcortical regions was observed in MCI (11)C-PIB+ patients relative to controls, MCI (11)C-PIB (negative) patients, and AD patients. No regional correlations were found between the 3 PET tracers.

CONCLUSION

Increased (11)C-DED binding throughout the brain of the MCI (11)C-PIB+ patients potentially suggests that astrocytosis is an early phenomenon in AD development.

Influence of multimorbidity on cognition in a normal aging population: a 12-year follow-up in the Maastricht Aging Study

OBJECTIVE

The prevalence of multimorbidity has risen considerably because of the increase in longevity and the rapidly growing number of older individuals. Today, only little is known about the influence of multimorbidity on cognition in a normal healthy aging population. The primary aim of the present study was to investigate the effect of multimorbidity on cognition over a 12-year period in an adult population with a large age range.

METHODS

Data were collected as part of the Maastricht Aging Study (MAAS), a prospective study into the determinants of cognitive aging. Eligible MAAS participants (N = 1763), 24-81 years older, were recruited from the Registration Network Family Practices (RNH) which enabled the use of medical records. The association between 96 chronic diseases, grouped into 23 disease clusters, and cognition on baseline, at 6 and 12 years of follow-up, were analyzed. Cognitive performance was measured in two main domains: verbal memory and psychomotor speed. A multilevel statistical analysis, a method that respects the hierarchical data structure, was used.

RESULTS

Multiple disease clusters were associated with cognition during a 12-year follow-up period in a healthy adult population. The disease combination malignancies and movement disorders multimorbidity also appeared to significantly affect cognition.

CONCLUSIONS

The current results indicate that a variety of medical conditions adversely affects cognition. However, these effects appear to be small in a normal healthy aging population.

Positron emission tomography imaging and clinical progression in relation to molecular pathology in the first Pittsburgh Compound B positron emission tomography patient with Alzheimer's disease

The accumulation of β-amyloid in the brain is an early event in Alzheimer’s disease. This study presents the first patient with Alzheimer’s disease who underwent positron emission tomography imaging with the amyloid tracer, Pittsburgh Compound B to visualize fibrillar β-amyloid in the brain. Here we relate the clinical progression, amyloid and functional brain positron emission tomography imaging with molecular neuropathological alterations at autopsy to gain new insight into the relationship between β-amyloid accumulation, inflammatory processes and the cholinergic neurotransmitter system in Alzheimer’s disease brain. The patient underwent positron emission tomography studies with ¹⁸F-fluorodeoxyglucose three times (at ages 53, 56 and 58 years) and twice with Pittsburgh Compound B (at ages 56 and 58 years), prior to death at 61 years of age. The patient showed a pronounced decline in cerebral glucose metabolism and cognition during disease progression, while Pittsburgh Compound B retention remained high and stable at follow-up. Neuropathological examination of the brain at autopsy confirmed the clinical diagnosis of pure Alzheimer’s disease. A comprehensive neuropathological investigation was performed in nine brain regions to measure the regional distribution of β-amyloid, neurofibrillary tangles and the levels of binding of ³H-nicotine and ¹²⁵I-α-bungarotoxin to neuronal nicotinic acetylcholine receptor subtypes, ³H-L-deprenyl to activated astrocytes and ³H-PK11195 to microglia, as well as butyrylcholinesterase activity. Regional in vivo¹¹C-Pittsburgh Compound B-positron emission tomography retention positively correlated with ³H-Pittsburgh Compound B binding, total insoluble β-amyloid, and β-amyloid plaque distribution, but not with the number of neurofibrillary tangles measured at autopsy. There was a negative correlation between regional fibrillar β-amyloid and levels of ³H-nicotine binding. In addition, a positive correlation was found between regional ¹¹C-Pittsburgh Compound B positron emission tomography retention and ³H-Pittsburgh Compound B binding with the number of glial fibrillary acidic protein immunoreactive cells, but not with ³H-L-deprenyl and ³H-PK-11195 binding. In summary, high ¹¹C-Pittsburgh Compound B positron emission tomography retention significantly correlates with both fibrillar β-amyloid and losses of neuronal nicotinic acetylcholine receptor subtypes at autopsy, suggesting a closer involvement of β-amyloid pathology with neuronal nicotinic acetylcholine receptor subtypes than with inflammatory processes.

II. Cognitive performance of middle-aged female rats is influenced by capacity to metabolize progesterone in the prefrontal cortex and hippocampus

Cognitive decline can occur with aging; however, some individuals experience less cognitive decline than do others. Secretion of ovarian hormones is reduced post-menopause and may contribute to cognitive function. The extent to which hormonal effects may be parsed out from other age-related factors to influence cognition is of interest. Middle-aged (12-month-old) female rats that were retired breeders were categorized as maintaining or declining reproductive function based upon their estrous cyclicity (regular 4-5 day cycles), fertility (> 60 % successful pregnancy), and fecundity (>10 pups/litter). Performance in object recognition, Y-maze, water maze, inhibitory avoidance, and contextual-cued fear conditioning was evaluated. Estradiol, progesterone (P(4)), dihydroprogesterone, and 5α-pregnan-3α-ol-20-one (3α,5α-THP) were assessed in medial prefrontal cortex (mPFC) and hippocampus; corticosterone was assessed in plasma. Rats maintaining reproductive function performed significantly better on the object recognition, Y-maze, water maze, inhibitory avoidance, and cued fear conditioning tasks than did rats with declining reproductive function. Steroid concentrations varied greatly within groups. Higher levels of P(4) in mPFC and hippocampus were associated with better Y-maze performance. In mPFC, higher levels of P(4) were associated with poorer inhibitory avoidance performance; greater levels of 3α,5α-THP were associated with better object memory. Neither estradiol nor corticosterone levels significantly contributed to cognitive performance. Thus, the capacity for cortico-limbic P(4) utilization may influence cognitive performance in aging.

Dynamic changes in PET amyloid and FDG imaging at different stages of Alzheimer's disease

In this study 5 patients with mild cognitive impairment (MCI) and 9 Alzheimer's disease (AD) patients underwent respectively 3- and 5-year follow-up positron emission tomography (PET) studies with N-methyl [(11)C] 2-(4-methylaminophenyl)-6-hydroxy-benzothiazole ((11)C-PIB) and (18)F-fluorodeoxyglucose ((18)F-FDG) to understand the time courses in AD disease processes. Significant increase in PIB retention as well as decrease in regional cerebral metabolic rate of glucose (rCMRglc) was observed at group level in the MCI patients while no significant change was observed in cognitive function. At group level the AD patients showed unchanged high PIB retention at 5-year follow-up compared with baseline. At the individual level, increased, stable, and decreased PIB retention were observed while disease progression was reflected in significant decrease in rCMRglc and cognition. In conclusion, after a long-term follow-up with PET, we observed an increase in fibrillar amyloid load in MCI patients followed by more stable level in clinical AD patients. The rCMRglc starts to decline in MCI patients and became more pronounced in clinical stage which related to continuous decline in cognition.

Glucose metabolism and PIB binding in carriers of a His163Tyr presenilin 1 mutation

Six young related pre-symptomatic carriers of a His163Tyr mutation in the presenilin 1 gene who will develop early onset familial Alzheimer's disease (eoFAD), and a control group of 23 non-carriers underwent (18)F-fluorodeoxyglucose positron emission tomography (FDG PET). The mutation carriers were followed-up after 2 years. Multivariate analysis showed clear separation of carriers from non-carriers on both occasions, with the right thalamus being the region contributing most to group differentiation. Statistical parametric mapping (SPM) revealed in the carriers non-significantly lower thalamic cerebral glucose metabolism (CMRglc) at baseline and significantly decreased CMRglc in the right thalamus at follow-up. One mutation carrier was followed-up with FDG PET 10 years after baseline and showed reductions in cognition and CMRglc in the posterior cingulate and the frontal cortex. This subject was diagnosed with AD 1 year later and assessed with an additional FDG as well as an (11)C-PIB PET scan 12 years after baseline. Global cortical CMRglc and cognition were distinctly decreased. PIB binding was comparable with sporadic AD patterns but showing slightly higher striatal levels.

Estimation of premorbid cognitive function based on word knowledge: The Swedish Lexical Decision Test (SLDT)

In clinical neuropsychology, the present status of a patient is evaluated in relation to the assumed premorbid status. However, in Sweden, existing methods to assess premorbid status are far from optimal. In the present study, the design and evaluation of a Swedish Lexical Decision Test (SLDT) for premorbid global cognitive function (i.e., premorbid intelligence) is described. The design was based on the empirical finding that, in general adult population, word knowledge is strongly associated with measures of global cognitive functioning. Linear stepwise regression analysis demonstrated that SLDT findings accounted for 48% of the variance of global cognitive function as assessed by the Full Scale Intelligence Quotient (FSIQ) from the Wechsler Adult Intelligence Scale Revised (WAIS-R). Demographic variables alone accounted for 31% and a combination of SLDT results and demographics accounted for 60%. Psychometric properties are presented using data from 109 healthy individuals stratified according to age, gender, and level of education. In addition, a case of Alzheimer's disease is presented to illustrate the relationship between SLDT performance and cognitive function. Finally, the theoretical foundation for the relationship between word knowledge and global cognitive function is discussed.

PET imaging of amyloid deposition in patients with mild cognitive impairment

It is of great clinical value to identify subjects at a high risk of developing AD. We previously found that the amyloid positron emission tomography (PET) tracer PIB showed a robust difference in retention in the brain between AD patients and healthy controls (HC). Twenty-one patients diagnosed with MCI (mean age 63.3+/-7.8 (S.D.) years) underwent PET studies with (11)C-PIB, and (18)F-fluoro-deoxy-glucose (FDG) to measure cerebral glucose metabolism, as well as assessment of cognitive function and CSF sampling. Reference group data from 27 AD patients and 6 healthy controls, respectively, were used for comparison. The mean cortical PIB retention for the MCI patients was intermediate compared to HC and AD. Seven MCI patients that later at clinical follow-up converted to AD (8.1+/-6.0 (S.D.) months) showed significant higher PIB retention compared to non-converting MCI patients and HC, respectively (ps<0.01). The PIB retention in MCI converters was comparable to AD patients (p>0.01). Correlations were observed in the MCI patients between PIB retention and CSF Abeta(1-42), total Tau and episodic memory, respectively.