What the study of persons at risk for familial Alzheimer's disease can tell us about the earliest stages of the disorder: a review

Use of the Spanish English Neuropsychological Assessment Scale in older adult Latines and those at risk for autosomal dominant Alzheimer's disease

OBJECTIVE

The Spanish English Neuropsychological Assessment Scale (SENAS) is a cognitive battery with English and Spanish versions for use with persons for whom either language is predominant. Few studies have examined its utility outside the normative sample. The current study examined SENAS performance in samples of older adult Latines and Latines with or at risk for autosomal dominant Alzheimer's disease (ADAD) mutations.

METHOD

The SENAS was administered to 202 older adults from the Los Angeles Latino Eye Study (LALES) and 29 adults with (carriers) or without (non-carriers) mutations causing ADAD. We examined associations between SENAS, age, education, and language (LALES) and between SENAS, estimated years from familial age of dementia diagnosis, education, language, and acculturation (ADAD). Partial correlations were used to examine differences in correlational strength between estimated years from familial age of dementia diagnosis and SENAS scores among ADAD carriers compared to chronological age and SENAS in the LALES sample. Exploratory t-tests were performed to examine SENAS performance differences between ADAD carriers and non-carriers.

RESULTS

In an older adult sample (LALES), increased age correlated with worse verbal delayed recall; English fluency and higher education correlated with better naming and visuospatial subtest performance. Among ADAD carriers, verbal and nonverbal delayed recall and object naming subtest performance worsened as they approached their familial age of dementia diagnosis. English fluency and higher U.S.-acculturation were related to better SENAS performance among carriers and non-carriers. Tests of verbal delayed recall and object naming best distinguished ADAD carriers from their familial non-carrier counterparts.

CONCLUSIONS

Verbal delayed recall and object naming measures appear to be most sensitive to age-related changes in older adult samples and mutation-related changes in distinguishing ADAD carriers from non-carriers. Future research should examine the sensitivity of SENAS in other samples, such as larger samples of symptomatic ADAD carriers and other AD subtypes.

Locus coeruleus integrity is related to tau burden and memory loss in autosomal-dominant Alzheimer's disease

Abnormally phosphorylated tau, an indicator of Alzheimer's disease, accumulates in the first decades of life in the locus coeruleus (LC), the brain's main noradrenaline supply. However, technical challenges in in-vivo assessments have impeded research into the role of the LC in Alzheimer's disease. We studied participants with or known to be at-risk for mutations in genes causing autosomal-dominant Alzheimer's disease (ADAD) with early onset, providing a unique window into the pathogenesis of Alzheimer's largely disentangled from age-related factors. Using high-resolution MRI and tau PET, we found lower rostral LC integrity in symptomatic participants. LC integrity was associated with individual differences in tau burden and memory decline. Post-mortem analyses in a separate set of carriers of the same mutation confirmed substantial neuronal loss in the LC. Our findings link LC degeneration to tau burden and memory in Alzheimer's, and highlight a role of the noradrenergic system in this neurodegenerative disease.

Cerebrospinal Fluid YKL-40 and Neurogranin in Familial Alzheimer's Disease: A Pilot Study

BACKGROUND

YKL-40 and neurogranin are promising additional cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) which reflect different underlying disease mechanisms.

OBJECTIVE

To compare the levels of CSF YKL-40 and neurogranin between asymptomatic carriers of familial AD (FAD) mutations (MC) and non-carriers (NC) from the same families. Another objective was to assess changes in YKL-40 and neurogranin, from the presymptomatic to clinical phase of FAD.

METHODS

YKL-40 and neurogranin, as well as Aβ42, total tau-protein, and phospho-tau, were measured in the CSF of 14 individuals carrying one of three FAD mutations, APPswe (p.KM670/671NL), APParc (p.E693G), and PSEN1 (p.H163Y), as well as in 17 NC from the same families. Five of the MC developed mild cognitive impairment (MCI) during follow-up.

RESULTS

In this pilot study, there was no difference in either CSF YKL-40 or neurogranin when comparing the presymptomatic MC to the NC. YKL-40 correlated positively with expected years to symptom onset and to age in both the MC and the NC, while neurogranin had no correlation to either variable in either of the groups. A subgroup of the participants underwent more than one CSF sampling in which half of the MC developed MCI during follow-up. The longitudinal data showed an increase in YKL-40 levels in the MC as the expected symptom onset approached. Neurogranin remained stable over time in both the MC and the NC.

CONCLUSION

These findings support a positive correlation between progression from presymptomatic to symptomatic AD and levels of CSF YKL-40, but not neurogranin.

Berberine: A Plant-derived Alkaloid with Therapeutic Potential to Combat Alzheimer's disease

Berberine (a protoberberine isoquinoline alkaloid) has shown promising pharmacological activities, including analgesic, anti-inflammatory, anticancer, antidiabetic, anti-hyperlipidemic, cardioprotective, memory enhancement, antidepressant, antioxidant, anti-nociceptive, antimicrobial, anti- HIV and cholesterol-lowering effects. It is used in the treatment of the neurodegenerative disorder. It has strong evidence to serve as a potent phytoconstituent in the treatment of various neurodegenerative disorders such as AD. It limits the extracellular amyloid plaques and intracellular neurofibrillary tangles. It has also lipid-glucose lowering ability, hence can be used as a protective agent in atherosclerosis and AD. However, more detailed investigations along with safety assessment of berberine are warranted to clarify its role in limiting various risk factors and AD-related pathologies. This review highlights the pharmacological basis to control oxidative stress, neuroinflammation and protective effect of berberine in AD, which will benefit to the biological scientists in understanding and exploring the new vistas of berberine in combating Alzheimer's disease.

Aging related cognitive changes associated with Alzheimer's disease in Down syndrome

OBJECTIVE

Individuals with Down syndrome (DS) have an extremely high genetic risk for Alzheimer's disease (AD), however, the course of cognitive decline associated with progression to dementia is ill-defined. Data-driven methods can estimate long-term trends from cross-sectional data while adjusting for variability in baseline ability, which complicates dementia assessment in those with DS.

METHODS

We applied an event-based model to cognitive test data and informant-rated questionnaire data from 283 adults with DS (the largest study of cognitive functioning in DS to date) to estimate the sequence of cognitive decline and individuals' disease stage.

RESULTS

Decline in tests of memory, sustained attention/motor coordination, and verbal fluency occurred early, demonstrating that AD in DS follows a similar pattern of change to other forms of AD. Later decline was found for informant measures. Using the resulting staging model, we showed that adults with a clinical diagnosis of dementia and those with APOE 3:4 or 4:4 genotype were significantly more likely to be staged later, suggesting that the model is valid.

INTERPRETATION

Our results identify tests of memory and sustained attention may be particularly useful measures to track decline in the preclinical/prodromal stages of AD in DS whereas informant-measures may be useful in later stages (i.e. during conversion into dementia, or postdiagnosis). These results have implications for the selection of outcome measures of treatment trials to delay or prevent cognitive decline due to AD in DS. As clinical diagnoses are generally made late into AD progression, early assessment is essential.

Subjective memory complaints are associated with brain activation supporting successful memory encoding

Subjective memory complaints, the perceived decline in cognitive abilities in the absence of clinical deficits, may precede Alzheimer's disease. Individuals with subjective memory complaints show differential brain activation during memory encoding; however, whether such differences contribute to successful memory formation remains unclear. Here, we investigated how subsequent memory effects, activation which is greater for hits than misses during an encoding task, differed between healthy older adults aged 50 to 85 years with (n = 23) and without (n = 41) memory complaints. Older adults with memory complaints, compared to those without, showed lower subsequent memory effects in the occipital lobe, superior parietal lobe, and posterior cingulate cortex. In addition, older adults with more memory complaints showed a more negative subsequent memory effects in areas of the default mode network, including the posterior cingulate cortex, precuneus, and ventromedial prefrontal cortex. Our findings suggest that for successful memory formation, older adults with subjective memory complaints rely on distinct neural mechanisms which may reflect an overall decreased task-directed attention.

Structural neuroimaging in preclinical dementia: From microstructural deficits and grey matter atrophy to macroscale connectomic changes

The last decade has witnessed a proliferation of neuroimaging studies characterising brain changes associated with Alzheimer's disease (AD), where both widespread atrophy and 'signature' brain regions have been implicated. In parallel, a prolonged latency period has been established in AD, with abnormal cerebral changes beginning many years before symptom onset. This raises the possibility of early therapeutic intervention, even before symptoms, when treatments could have the greatest effect on disease-course modification. Two important prerequisites of this endeavour are (1) accurate characterisation or risk stratification and (2) monitoring of progression using neuroimaging outcomes as a surrogate biomarker in those without symptoms but who will develop AD, here referred to as preclinical AD. Structural neuroimaging modalities have been used to identify brain changes related to risk factors for AD, such as familial genetic mutations, risk genes (for example apolipoprotein epsilon-4 allele), and/or family history. In this review, we summarise structural imaging findings in preclinical AD. Overall, the literature suggests early vulnerability in characteristic regions, such as the medial temporal lobe structures and the precuneus, as well as white matter tracts in the fornix, cingulum and corpus callosum. We conclude that while structural markers are promising, more research and validation studies are needed before future secondary prevention trials can adopt structural imaging biomarkers as either stratification or surrogate biomarkers.

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).

The effects of different familial Alzheimer's disease mutations on APP processing in vivo

BACKGROUND

Disturbed amyloid precursor protein (APP) processing is considered to be central to the pathogenesis of Alzheimer's disease (AD). The autosomal dominant form of the disease, familial AD (FAD), may serve as a model for the sporadic form of AD. In FAD the diagnosis of AD is reliable and presymptomatic individuals carrying FAD mutations can give valuable insights into the earliest stages of the disease where therapeutic interventions are thought to be the most effective.

METHODS

In the current cross-sectional study, products of APP processing (e.g., sAPPα, sAPPβ, Aβ38, Aβ40 and Aβ42) were measured in the cerebrospinal fluid (CSF) of individuals carrying one of three FAD mutations, APPswe (p.KM670/671NL), APParc (p.E693G) and PSEN1 (p.H163Y), as well as in non-mutation carriers from the same families.

RESULTS

We observed pathological APP processing in presymptomatic carriers of FAD mutations, with different profiles of APP and Aβ isoforms in the three mutation carrier groups, APPswe (p.KM670/671NL), APParc (p.E693G) and PSEN1 (p.H163Y), except for the well-established decrease in CSF Aβ42 that was found with all mutations.

CONCLUSIONS

These findings add to the current evidence that AD pathophysiology differs between disease-causing mutations and can be monitored in the presymptomatic disease stage by CSF analyses. This may also be important from a therapeutic standpoint, by opening a window to monitor effects of disease-modifying drugs on AD pathophysiology.

Nervous system disorders across the life course in resource-limited settings

The resiliency of the adult nervous system is markedly affected by the environment and the circumstances during infant and child development. As such, adults in resource-limited settings who may have experienced early deprivation are particularly vulnerable to subsequent neurological disorders. Adult populations in countries with relatively recent advances in economic development may still have a higher susceptibility to neurological illness or injury that is reflective of the socioeconomic environment that was present during that population’s infancy and childhood. Brain and peripheral nervous system research conducted over the past decade in resource-limited settings has led to an impressive and growing body of knowledge that informs our understanding of neurological function and dysfunction, independent of geography. Neurological conditions feature prominently in the burgeoning epidemic of non-communicable diseases facing low- and middle-income countries. Neurological research in these countries is needed to address this burden of disease. Although the burden of more prevalent and severe neurological disease poses public health and clinical challenges in settings with limited neurological expertise, the same factors, along with genetic heterogeneity and the relative absence of ingrained clinical care practices, offer circumstances well-suited for the conduct of crucial future research that is globally relevant.

A survey of attitudes toward clinical trials and genetic disclosure in autosomal dominant Alzheimer's disease

INTRODUCTION

Because of its genetic underpinnings and consistent age of onset within families, autosomal dominant Alzheimer's disease (ADAD) provides a unique opportunity to conduct clinical trials of investigational agents as preventative or symptom-delaying treatments. The design of such trials may be complicated by low rates of genetic testing and disclosure among persons at risk of inheriting disease-causing mutations.

METHODS

To better understand the attitudes toward genetic testing and clinical trials of persons at risk for ADAD, we surveyed participants in the Dominantly Inherited Alzheimer's Network (DIAN), a multisite longitudinal study of clinical and biomarker outcomes in ADAD that does not require learning genetic status to participate.

RESULTS

Eighty participants completed a brief anonymous survey by mail or on-line; 40 % reported knowing if they carried a gene mutation, 15 % did not know but expressed a desire to learn their genetic status, and 45 % did not know and did not desire to know their genetic status. Among participants who knew or wished to know their genetic status, 86 % were interested in participating in a clinical trial. Seventy-two percent of participants who did not wish to learn their genetic status reported that they would change their mind, if learning that they carried a mutation gave them the opportunity to participate in a clinical trial. Nearly all participants responded that they would be interested if an open-label extension were offered.

CONCLUSIONS

These results suggest that the availability of clinical trials to prevent ADAD can affect persons' desire to undergo genetic testing and that consideration can be given to performing studies in which such testing is required.

Genetic heterogeneity in Alzheimer disease and implications for treatment strategies

Since the original publication describing the illness in 1907, the genetic understanding of Alzheimer's disease (AD) has advanced such that it is now clear that it is a genetically heterogeneous condition, the subtypes of which may not uniformly respond to a given intervention. It is therefore critical to characterize the clinical and preclinical stages of AD subtypes, including the rare autosomal dominant forms caused by known mutations in the PSEN1, APP, and PSEN2 genes that are being studied in the Dominantly Inherited Alzheimer Network study and its associated secondary prevention trial. Similar efforts are occurring in an extended Colombian family with a PSEN1 mutation, in APOE ε4 homozygotes, and in Down syndrome. Despite commonalities in the mechanisms producing the AD phenotype, there are also differences that reflect specific genetic origins. Treatment modalities should be chosen and trials designed with these differences in mind. Ideally, the varying pathological cascades involved in the different subtypes of AD should be defined so that both areas of overlap and of distinct differences can be taken into account. At the very least, clinical trials should determine the influence of known genetic factors in post hoc analyses.

Dominantly Inherited Alzheimer Network: facilitating research and clinical trials

The Dominantly Inherited Alzheimer Network (DIAN) is an international registry of individuals at risk for developing autosomal dominant Alzheimer's disease (AD). Its primary aims are to investigate the temporal ordering of AD pathophysiological changes that occur in asymptomatic mutation carriers and to identify those markers that herald the transition from cognitive normality to symptomatic AD. DIAN participants undergo longitudinal evaluations, including clinical and cognitive assessments and measurements of molecular and imaging AD biomarkers. This review details the unique attributes of DIAN as a model AD biomarker study and how it provides the infrastructure for innovative research projects, including clinical trials. The recent design and launch of the first anti-amyloid-beta secondary prevention trial in AD, led by the related DIAN Trials Unit, also are discussed.

Perspectives on episodic-like and episodic memory

Episodic memory refers to the conscious recollection of a personal experience that contains information on what has happened and also where and when it happened. Recollection from episodic memory also implies a kind of first-person subjectivity that has been termed autonoetic consciousness. Episodic memory is extremely sensitive to cerebral aging and neurodegenerative diseases. In Alzheimer’s disease deficits in episodic memory function are among the first cognitive symptoms observed. Furthermore, impaired episodic memory function is also observed in a variety of other neuropsychiatric diseases including dissociative disorders, schizophrenia, and Parkinson disease. Unfortunately, it is quite difficult to induce and measure episodic memories in the laboratory and it is even more difficult to measure it in clinical populations. Presently, the tests used to assess episodic memory function do not comply with even down-sized definitions of episodic-like memory as a memory for what happened, where, and when. They also require sophisticated verbal competences and are difficult to apply to patient populations. In this review, we will summarize the progress made in defining behavioral criteria of episodic-like memory in animals (and humans) as well as the perspectives in developing novel tests of human episodic memory which can also account for phenomenological aspects of episodic memory such as autonoetic awareness. We will also define basic behavioral, procedural, and phenomenological criteria which might be helpful for the development of a valid and reliable clinical test of human episodic memory.

New genes and new insights from old genes: update on Alzheimer disease

PURPOSE OF REVIEW

This article discusses the current status of knowledge regarding the genetic basis of Alzheimer disease (AD) with a focus on clinically relevant aspects.

RECENT FINDINGS

The genetic architecture of AD is complex, as it includes multiple susceptibility genes and likely nongenetic factors. Rare but highly penetrant autosomal dominant mutations explain a small minority of the cases but have allowed tremendous advances in understanding disease pathogenesis. The identification of a strong genetic risk factor, APOE, reshaped the field and introduced the notion of genetic risk for AD. More recently, large-scale genome-wide association studies are adding to the picture a number of common variants with very small effect sizes. Large-scale resequencing studies are expected to identify additional risk factors, including rare susceptibility variants and structural variation.

SUMMARY

Genetic assessment is currently of limited utility in clinical practice because of the low frequency (Mendelian mutations) or small effect size (common risk factors) of the currently known susceptibility genes. However, genetic studies are identifying with confidence a number of novel risk genes, and this will further our understanding of disease biology and possibly the identification of therapeutic targets.

Comparison of clinical characteristics between familial and non-familial early onset Alzheimer's disease

Although familial Alzheimer's disease (FAD) is an early onset AD (EAD), most patients with EAD do not have a familial disorder. Recent guidelines recommend testing for genes causing FAD only in those EAD patients with two first-degree relatives. However, some patients with FAD may lack a known family history or other indications for suspecting FAD but might nonetheless be carriers of FAD mutations. The study was aimed to identify clinical features that distinguish FAD from non-familial EAD (NF-EAD). A retrospective review of a university-based cohort of 32 FAD patients with PSEN1-related AD and 81 with NF-EAD was conducted. The PSEN1 patients, compared to the NF-EAD patients, had an earlier age of disease onset (41.8 ± 5.2 vs. 55.9 ± 4.8 years) and, at initial assessment, a longer disease duration (5.1 ± 3.4 vs. 3.3 ± 2.6 years) and lower MMSE scores (10.74 ± 8.0 vs. 20.95 ± 5.8). Patients with NF-EAD were more likely to present with non-memory deficits, particularly visuospatial symptoms, than were FAD patients. When age, disease duration, and MMSE scores were controlled in a logistical regression model, FAD patients were more likely to have significant headaches, myoclonus, gait abnormality, and pseudobulbar affect than those with NF-EAD. In addition to a much younger age of onset, FAD patients with PSEN1 mutations differed from those with NF-EAD by a history of headaches and pseudobulbar affect, as well as myoclonus and gait abnormality on examination. These may represent differences in pathophysiology between FAD and NF-EAD and in some contexts such findings should lead to genetic counseling and appropriate recommendations for genetic testing for FAD.

Plasma signaling proteins in persons at genetic risk for Alzheimer disease: influence of APOE genotype

OBJECTIVE

To study the effect of familial Alzheimer disease (FAD) mutations and APOE genotype on plasma signaling protein levels.

DESIGN

Cross-sectional comparison of plasma levels of 77 proteins measured using multiplex immune assays.

SETTING

A tertiary referral dementia research center.

PARTICIPANTS

Thirty-three persons from families harboring PSEN1 or APP mutations, aged 19 to 59 years.

MAIN OUTCOME MEASURES

Protein levels were compared between FAD mutation carriers (MCs) and noncarriers (NCs) and among APOE genotype groups, using multiple linear regression models.

RESULTS

Twenty-one participants were FAD MCs and 12 were NCs. Six had the APOE ε2/3, 6 had the ε3/4, and 21 had the ε3/3 genotype. Levels of 17 proteins differed among APOE genotype groups, and there were significant interactions between age and APOE genotype for 12 proteins. Plasma levels of apolipoprotein E and superoxide dismutase 1 were highest in the ε2 carriers, lowest in ε4 carriers, and intermediate in the ε3 carriers. Levels of multiple interleukins showed the opposite pattern and, among the ε4 carriers, demonstrated significant negative correlations with age. Although there were no significant differences between FAD MCs and NCs, there were interactions between mutation status and APOE genotype for 13 proteins.

CONCLUSIONS

We found different patterns of inflammatory markers in young and middle-aged persons among APOE genotype groups. The APOE ε4 carriers had the lowest levels of apolipoprotein E. Young ε4 carriers have increased inflammatory markers that diminish with age. We demonstrated altered inflammatory responses in young and middle adulthood in ε4 carriers that may relate to AD risk later in life.

Object recognition as a measure of memory in 1-2 years old transgenic minipigs carrying the APPsw mutation for Alzheimer's disease

Alzheimer's disease (AD) is a disabling, fatal disease, where animal models potentially can enable investigation of aetiology and treatment. The first litter of Göttingen minipigs carrying a mutation for human AD was born in 2007, showing transgene expression. In human AD patients, memory impairment is the most striking and consistent feature. The aim of the present study was to examine effects of the APPsw transgene on memory of AD minipigs compared with non-transgenic controls at two ages (1-2 years) using the spontaneous object recognition test (SORT), which is based on behavioural discrimination of familiar and novel objects. No significant difference between AD minipigs and controls was found when comparing object recognition as a measure of memory. The minipigs did explore the novel object significantly more than the familiar, indicating the expected recognition of the familiar object. Two different inter-phase intervals were used (IPI: 10-40 min). For both ages, object recognition was evident using 10 min IPI. When using 40 min IPI, object recognition was evident only at age 1 year. Comparing memory of a relatively small group of AD minipigs and controls at two rather young ages using the SORT, we were not able to show memory impairment in APPsw carrying minipigs. Being an age-dependent disease, the transgene is expected to cause AD-like symptoms in this porcine model, and the SORT should be repeated at older ages.

Cerebrospinal fluid biomarkers and proximity to diagnosis in preclinical familial Alzheimer's disease

BACKGROUND/AIMS

Biological markers of utility in tracking Alzheimer's disease (AD) during the presymptomatic prodromal phase are important for prevention studies. Changes in cerebrospinal fluid (CSF) levels of 42-amino-acid β-amyloid (Aβ(42)), total tau protein (t-tau) and phosphorylated tau at residue 181 (p-tau(181)) during this state are incompletely characterized.

METHODS

We measured CSF markers in 13 carriers of familial AD (FAD) mutations that are fully penetrant for causing AD (PSEN1 and APP) and in 5 non-mutation-carrying family members.

RESULTS

Even among the entirely presymptomatic mutation carriers (n = 9), Aβ(42) was diminished (388.7 vs. 618.4 pg/ml, p = 0.004), and t-tau (138.5 vs. 50.5 pg/ml, p = 0.002) and p-tau(181) (71.7 vs. 24.6 pg/ml, p = 0.003) were elevated. There was a negative correlation between Aβ(42) levels and age relative to the family-specific age of dementia diagnosis.

CONCLUSIONS

Our data are consistent with a decline in CSF Aβ(42) levels occurring at least 20 years prior to clinical dementia in FAD.

Propositional density and apolipoprotein E genotype among persons at risk for familial Alzheimer's disease

BACKGROUND/AIMS

A relationship between decreased propositional density (p-density) in young adulthood and future risk for Alzheimer's disease (AD) has been postulated, but multiple interpretations of the nature of this relationship are possible. This study explored the relationship between familial AD (FAD) mutation status, apolipoprotein E (APOE) genotype, and p-density.

METHODS

Thirty-five non-demented persons at risk for FAD mutations were recruited. Subjects wrote brief biographical essays from which p-density, the ratio of the number of unique ideas to the number of words in the text, was calculated. mixed-effects regression models were used to examine the relationship of p-density and fad mutation status and apoe genotype.

RESULTS

FAD mutation status was not significantly associated with p-density. However, results from both models indicated that the presence of the APOE ε4 allele was significantly associated with p-density (p < 0.0001), with APOE ε4 carriers having lower p-density than non-carriers.

CONCLUSIONS

Our results are consistent with an influence of APOE status on p-density in young adulthood that is independent of the AD risk per se and suggest the previous finding of increased risk for the development of AD in persons with decreased p-density may be related to APOE genotype.

Brain activation disturbance for target detection in patients with mild cognitive impairment: an fMRI study

Functional brain imaging in mild cognitive impairment (MCI) reveals differences in activation of task-relevant brain areas between patients and age-matched healthy controls. However, some studies reported hyperactivation and others hypoactivation in MCI compared with controls. The inconsistencies may be explained by compensatory mechanisms due to high complexity of the applied tasks. The oddball task is a simple paradigm that is known to activate a widespread network in the brain, involving attentional and monitoring mechanisms. In the present study, we examined amnestic or amnestic multidomain MCI patients (n = 12) and healthy controls (n = 13) in an auditory oddball task. Participants had to respond to infrequent targets and inhibit response to infrequent novel-nontarget stimuli. Lower stimulus related activation was found in MCI patients compared with healthy controls in parts of the middle temporal gyrus, the temporal pole, regions along the superior temporal sulcus, in the left cuneus, the left supramarginal gyrus, the anterior cingulated cortex and in the left inferior and middle frontal gyrus. Activation for oddball stimuli is assumed to reflect an automatic reflexive engagement of many brain regions in response to potentially important changes in the environment as well as cognitive control to monitor responses. The mechanisms of attention and cognitive control may be severely impaired in MCI and thus, underlie the cognitive deficits of this clinical group.

The Cambridge Semantic Memory Test Battery: detection of semantic deficits in semantic dementia and Alzheimer's disease

The aims of this study were (a) to explore the utility of, and make more widely available, an updated and extended version of the Cambridge Semantic Memory test battery, and (b) to use this battery in conjunction with other tests to characterise the profile of several different forms of progressive cognitive impairment: semantic dementia (SD, n = 15), mild cognitive impairment (MCI, n = 7), established Alzheimer's disease (AD) (n = 8), all in comparison to normal controls (n = 45). The semantic battery is useful in a variety of ways for exploring the nature of semantic deficits; on its own, however, it does not provide sensitive differentiation between patients with AD and SD. An assessment including measures of episodic memory and visuospatial abilities as well as the semantic battery is recommended for good characterisation of the cognitive profiles associated with SD and AD.

Current therapeutic targets for the treatment of Alzheimer's disease

Alzheimer's disease is a progressive neurodegenerative disease for which no cure exists. There is a substantial need for new therapies that offer improved symptomatic benefit and disease-slowing capabilities. In recent decades there has been substantial progress in understanding the molecular and cellular changes associated with Alzheimer's disease pathology. This has resulted in identification of a large number of new drug targets. These targets include, but are not limited to, therapies that aim to prevent production of or remove the amyloid-beta protein that accumulates in neuritic plaques; to prevent the hyperphosphorylation and aggregation into paired helical filaments of the microtubule-associated protein tau; and to keep neurons alive and functioning normally in the face of these pathologic challenges. We provide a review of these targets for drug development.

Increased prevalence of significant recurrent headache in preclinical familial Alzheimer's disease mutation carriers

BACKGROUND/AIMS

A previous study found a high prevalence of headaches in persons with familial Alzheimer's disease (FAD) due to a PSEN1 mutation. In our study we compared the prevalence of headaches between nondemented FAD mutation carriers (MCs) and non-mutation-carrying controls (NCs).

METHODS

A headache questionnaire that assessed the prevalence of significant headaches and diagnosis of migraine and aura by ICHD-2 criteria was administered to 27 individuals at risk for FAD. Frequency of significant headaches, migraine, and aura were compared between MCs and NCs by chi(2) or Fisher's exact tests.

RESULTS

Twenty-three subjects were at risk for PSEN1 mutations and 4 for an APP substitution. The majority of subjects were female (23/27). MCs were more likely to report significant recurrent headache than NCs (67 vs. 25%, p = 0.031). Forty percent of MCs had headaches that met criteria for migraine whereas 17% of NCs met such criteria. The tendency for a higher prevalence of headaches in MCs held for different PSEN1 and APP mutations but was not significant unless all families were combined.

CONCLUSIONS

In this population, headache was more common in nondemented FAD MCs than NCs. Possible mechanisms for this include cerebral inflammation, aberrant processing of Notch3, or disrupted intracellular calcium regulation.

Children of persons with Alzheimer disease: what does the future hold?

Children of persons with Alzheimer disease (AD), as a group, face an increased risk of developing AD. Many of them, throughout their adult lives, seek input on how to reduce their chances of one day suffering their parent's fate. We examine the state of knowledge with respect to risk and protective factors for AD and recommend a research agenda with special emphasis on AD offspring.