Molecular pathology of Alzheimer's disease

Tocotrienol Rich Fraction Supplementation Modulate Brain Hippocampal Gene Expression in APPswe/PS1dE9 Alzheimer's Disease Mouse Model

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by loss of memory and other cognitive abilities. AD is associated with aggregation of amyloid-β (Aβ) deposited in the hippocampal brain region. Our previous work has shown that tocotrienol rich fraction (TRF) supplementation was able to attenuate the blood oxidative status, improve behavior, and reduce fibrillary-type Aβ deposition in the hippocampus of an AD mouse model. In the present study, we investigate the effect of 6 months of TRF supplementation on transcriptome profile in the hippocampus of APPswe/PS1dE9 double transgenic mice. TRF supplementation can alleviate AD conditions by modulating several important genes in AD. Moreover, TRF supplementation attenuated the affected biological process and pathways that were upregulated in the AD mouse model. Our findings indicate that TRF supplementation can modulate hippocampal gene expression as well as biological processes that can potentially delay the progression of AD.

Biological Effects of Tetrahydroxystilbene Glucoside: An Active Component of a Rhizome Extracted from Polygonum multiflorum

Polygonum multiflorum Thunb. (PM), a traditional Chinese medicinal herb, has been widely used in the Orient as a tonic and antiaging agent. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG, C20H22O9, FW = 406.38928) is one of the active components extracted from PM. TSG is an antioxidant agent, which exhibits remarkable antioxidative activities in vivo and in vitro. The antioxidant effect of TSG is achieved by its radical-scavenging effects. TSG can inhibit apoptosis and protect neuronal cells against injury through multifunctional cytoprotective pathways. TSG performs prophylactic and therapeutic activities against Alzheimer's disease, Parkinson's disease, and cerebral ischemia/reperfusion injury. It is also antiatherosclerotic and anti-inflammatory. However, the mechanisms underlying these pharmacological activities are unclear. This study aimed at reviewing experimental studies and describing the effectiveness and possible mechanisms of TSG.

A novel liquid chromatography/mass spectrometry method for determination of neurotransmitters in brain tissue: Application to human tauopathies

Neurotransmitters, small molecules widely distributed in the central nervous system are essential in transmitting electrical signals across neurons via chemical communication. Dysregulation of these chemical signaling molecules is linked to numerous neurological diseases including tauopathies. In this study, a precise and reliable liquid chromatography method was established with tandem mass spectrometry detection for the simultaneous determination of aspartic acid, asparagine, glutamic acid, glutamine, γ-aminobutyric acid, N-acetyl-l-aspartic acid, pyroglutamic acid, acetylcholine and choline in human brain tissue. The method was successfully applied to the analysis of human brain tissues from three different tauopathies; corticobasal degeneration, progressive supranuclear palsy and parkinsonism-dementia complex of Guam. Neurotransmitters were analyzed on ultra-high performance chromatography (UHPLC) using an ethylene bridged hybrid amide column coupled with tandem mass spectrometry (MS/MS). Identification and quantification of neurotransmitters was carried out by ESI+ mass spectrometry detection. We optimized sample preparation to achieve simple and fast extraction of all nine analytes. Our method exhibited an excellent linearity for all analytes (all coefficients of determination >0.99), with inter-day and intra-day precision yielding relative standard deviations 3.2%-11.2% and an accuracy was in range of 92.6%-104.3%. The present study, using the above method, is the first to demonstrate significant alterations of brain neurotransmitters caused by pathological processes in the brain tissues of patient with three different tauopathies.

Alzheimer's disease or Alzheimer's syndrome?: a longitudinal computed tomography neuroradiological follow-up study of 56 cases diagnosed clinically as Alzheimer's disease

BACKGROUND

Some 200 patients, including those with Alzheimer's disease and other types of dementia, stay year-round in Yokohama - Houyuu Hospital. They undergo computed tomography (CT) neuroradiological examination at least once or twice a year. For this study, the accumulative data, including clinical and neuroradiological, were analyzed.

METHODS

Differential diagnoses of Alzheimer's disease were performed in accordance with the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria. The 56 patients (15 men, 41 women) included in this study underwent in-hospital observation on average for 4.4 years (range: 1-10 years). The patients were classified into four groups according to the age of disease onset. The CT findings were summarized for each group and then compared among the groups to determine if there were any differences related to age of onset and, if so, to identify and analyze them.

RESULTS

(1) The duration of deceased cases' total clinical course (in years) compared among the four groups. In general, the degree of dementia was more severe among those with earlier disease onset. (2) In cases admitted within 2 years from onset (n =14), the suspected initiating focus of cortical atrophy occurred in the frontal lobe (n = 6), the temporal lobe (n = 6), or the fronto-temporal lobes (n = 2). (3) Although CT findings generally showed that the more severe cases had earlier onset, serial CT examinations in each case showed widely different pathologies in degree, nature and manner of progression, regardless of group classification. (4) The earliest sites of brain atrophy, sites of its severest involvement within the brain, and neuroradiological development of the cerebral cortex pathology in combination with hemispheric white matter, lateral ventricles, and third ventricles varied among the four groups and between case within each group. Alzheimer's disease could not be subclassified simply by the age of clinical onset.

CONCLUSION

Cases of so-called Alzheimer's disease, as observed through continued clinical follow-up and serial CT examinations, appear so diverse in symptomatology and radiological pathomorphology that it is difficult to consider them a single nosological entity. The pathology of Alzheimer's disease has to be reconsidered in accordance with the variety observed in the sequential development of neuroradiological findings. The pathology must be reconstructed in terms of topographical dimensions and chronological developments. The diagnosis of Alzheimer's disease appears to be not so simple based on any conventional diagnostic operational standards.

Molecular Targets in Alzheimer's Disease: From Pathogenesis to Therapeutics

Alzheimer's disease (AD) is characterized by progressive cognitive decline usually beginning with impairment in the ability to form recent memories. Nonavailability of definitive therapeutic strategy urges developing pharmacological targets based on cell signaling pathways. A great revival of interest in nutraceuticals and adjuvant therapy has been put forward. Tea polyphenols for their multiple health benefits have also attracted the attention of researchers. Tea catechins showed enough potentiality to be used in future as therapeutic targets to provide neuroprotection against AD. This review attempts to present a concise map of different receptor signaling pathways associated with AD with an insight into drug designing based on the proposed signaling pathways, molecular mechanistic details of AD pathogenesis, and a scientific rationale for using tea polyphenols as proposed therapeutic agents in AD.

Is aging part of Alzheimer's disease, or is Alzheimer's disease part of aging?

For 70 years after Alois Alzheimer described a disorder of tangle-and-plaque dementia, Alzheimer's disease was a condition of the relatively young. Definitions of Alzheimer's disease (AD) have, however, changed over the past 30 years and under the revised view AD has truly become an age-related disease. Most now diagnosed with AD are elderly and would not have been diagnosed with AD as originally conceived. Accordingly, younger patients that qualify for a diagnosis of AD under both original and current Alzheimer's disease constructs now represent an exceptionally small percentage of the diagnosed population. The question of whether pathogenesis of the "early" and "late" onset cases is similar enough to qualify as a single disease was previously raised although not conclusively settled. Interestingly, debate on this issue has not kept pace with advancing knowledge about the molecular, biochemical and clinical underpinnings of tangle-and-plaque dementias. Since the question of whether both forms of AD share a common pathogenesis could profoundly impact diagnostic and treatment development efforts, it seems worthwhile to revisit this debate.

Auditory adaptation is differentially impaired in familial and sporadic Alzheimer's disease

Neurophysiologic measures are particularly sensitive to alterations in attention and arousal. The purpose of this study was to evaluate the auditory adaptation of normal and mildly demented elderly people. We compared the automatic behavior of an auditory evoked potential (N100) in three age-matched groups of elderly subjects, one with familial Alzheimer's disease (AD), one with sporadic AD and one healthy group. All AD subjects corresponded clinically and neuropsychologically with the early stage of dementia. The dynamic range of auditory adaptation is known to be related to age, and normal auditory adaptation for the age was observed in our healthy aged and sporadic AD subjects, whereas the familial AD subjects lacked normal adaptation. The familial AD subjects also showed statistically significantly smaller peak amplitudes and shorter latencies of the N100 throughout the habituation test. This persistent difference in automatic habituation of sensory responses supports the view that different subtypes of AD are differentially affected. The observed differences give an objective measure of the impaired involuntary adaptive functions of neuronal networks involved in auditory processing in subtypes of AD. Since habituation reflects the most primitive stage of learning and short-term memory, altered habituation may predict faster deterioration of clinical status in the familial group of AD subjects.

Differential alterations in muscarinic receptor subtypes in Alzheimer's disease: implications for cholinergic-based therapies

Molecular subtypes of muscarinic receptors (m1-m5) are novel targets for cholinergic replacement therapies in Alzheimer's disease (AD). However, knowledge concerning the relative distribution, abundance and functional status of these receptors in human brain and AD is incomplete. Recent data from our laboratory have demonstrated a defect in the ability of the M1 receptor subtype to form a high affinity agonist-receptor-G protein complex in AD frontal cortex. This defect is manifested by decreased M1 receptor-stimulated GTPgammaS binding and GTPase activity and by a loss in receptor-stimulated phospholipase C activity. Normal levels of G proteins suggest that the aberrant receptor-G protein interaction may result from an altered form of the m1 receptor in AD. The combined use of radioligand binding and receptor-domain specific antibodies has permitted the re-examination of the status of muscarinic receptor subtypes in the human brain. In AD, normal levels of m1 receptor [3H]-pirenzepine binding contrasted with diminished m1 immunoreactivity, further suggesting that there is an altered form of the m1 receptor in the disease. Reduced m2 immunoreactivity was consistent with decreased numbers of m2 binding sites. Increased levels of m4 receptors were observed in both binding and immunoreactivity measurements. These findings suggest one possible explanation for the relative ineffectiveness of cholinergic replacement therapies used to date and suggest potential new directions for development of effective therapeutic strategies for AD.

Reduced neuronal activity and reactivation in Alzheimer's disease

1. Alzheimer's disease is a multifactorial disease in which age and APOE-epsilon 4 are important risk factors. Various mutations and even viral infections such as herpes simplex (Itzhaki et al., 1997) may play an additional role. 2. The neuropathological hallmarks of Alzheimer's disease (AD), i.e. amorphous plaques, neuritic plaques (NPs), pretangles, neurofibrillary tangles (NFT) and cell death are not part of a single pathogenetic cascade but are basically independent phenomena. 3. Pretangles can occur in neurons from which the metabolic rate is not altered. However, in brain areas where classical AD changes, i.e. NPs and NFTs, are present, such as the CA1 area of the hippocampus, the nucleus basalis of Meynert and the tuberomamillary nucleus, a decreased metabolic rate is found. Decreased metabolic rate appears to be an independent phenomenon in Alzheimer's disease. It is not induced by the presence of pretangles, NFT or NPs. 4. Decreased metabolic rate may precede cognitive impairment and is thus an early occurring hallmark of Alzheimer's disease, which, in principle, may be reversible. The observation that the administration of glucose or insulin enhances memory in Alzheimer patients also supports the view that Alzheimer's disease is basically a metabolic disease. Moreover, several observations indicate that activated neurons are better able to withstand aging and AD, a phenomenon paraphrased by us as "use it or lose it". It is, therefore, attractive to direct the development of therapeutic strategies towards restimulation of neuronal metabolic rate in order to improve cognition and other symptoms in Alzheimer's disease. A number of pharmacological and non-pharmacological studies support the concept that activation of the brain indeed has beneficial effects on several aspects of cognition and other central functions.

Decade of the brain: neurological advances

In the last half century, neurological developments have been phenomenal and have escalated in this decade of the brain. Many infective disorders have been conquered, but AIDS has posed new challenges. Neuropharmacology has transformed the management of parkinsonism and epilepsy. New imaging techniques such as CT, NMR, PET and ultrasonic scanning have presented us with remarkable images of the nervous system in health and disease. Steroids control many autoimmune disorders; beta-interferon and other new drugs have begun to influence multiple sclerosis. Intensive care has saved many of those with head injury or acute neurological disorders, and we have greatly improved methods of rehabilitation. There are still many incurable neurological disorders but none are untreatable. Today's discovery in basic science brings tomorrow's improvement in patient care, as is clearly shown by molecular genetics. Some neurological and neuromuscular diseases in which the causal gene or genes have been located and characterised and in which the missing or abnormal gene product has been identified will be mentioned, as well as the prospects of carrier detection, antenatal diagnosis and gene therapy.

Longitudinal SPECT study in Alzheimer's disease: relation to apolipoprotein E polymorphism

OBJECTIVES

In mild Alzheimer's disease, SPECT imaging of regional cerebral blood flow has highlighted deficits in the posterior association cortex, and later in the disease process, the deficit spreads to involve the frontal cortex. The sigma4 allele of apolipoprotein E is a risk factor for Alzheimer's disease. The effect of apolipoprotein E polymorphism on cerebral perfusion was studied. The hypothesis was that those patients with Alzheimer's disease who carry the sigma4 allele would have more severe cerebral hypoperfusion.

METHODS

Thirty one patients with Alzheimer's disease and eight age and sex matched control subjects were examined in a three year longitudinal study. Patients with Alzheimer's disease were divided into subgroups according to their number of sigma4 alleles. Regional cerebral blood flow ratios referred to the cerebellum were examined by 99mTc-HMPAO SPECT. Apolipoprotein E genotypes were determined by digestion of polymerase chain reaction products with the restriction enzyme Hha1.

RESULTS

All patients with Alzheimer's disease had bilateral temporoparietal hypoperfusion compared with control subjects. The two sigma4 allele subgroups had the lowest ratios at the baseline assessment in the parietal and occipital cortices, and at the follow up in the temporal, parietal, and occipital cortices. They had the highest reduction in percentage terms in the temporal and occipital cortices compared with the other subgroups. However, the global clinical severity did not differ at the baseline or follow up examinations between the subgroups.

CONCLUSION

Apolipoprotein E polymorphism is involved in the pathogenesis and heterogeneity of Alzheimer's disease as the most severe cerebral hypoperfusion was found in the sigma4 allele subgroups. This might have implications for therapeutic approaches in Alzheimer's disease.

Pathology of familial Alzheimer's disease with Lewy bodies

The neuropathological findings of three cases from two pedigrees with early onset familial Alzheimer's disease (FAD) are reported. Affected members of the first family, including cases 1 and 2 reported here, are known to have 717 valine to isoleucine mutation of the amyloid precursor protein (APP) gene, while the genetic background of the disease has not been clarified yet in the second family. In all three cases, in addition to the classical histological findings associated with Alzheimer's disease (AD), both nigral and cortical Lewy bodies (LBs) occurred. The association of LBs with AD type pathology, which may be observed in both sporadic and familial AD, raises important nosological issues. These include a possible overlap between AD and other neurodegenerative conditions presenting primarily with LBs. In this respect the clinically and neuropathologically distinct disease entity described under the terms of "senile dementia of the Lewy body type" and "Lewy body variant of AD" may be especially important. The occurrence of LBs in association with severe AD-type histological changes in sporadic and especially in some familial AD cases indicate that these inclusions may be another expression of the altered cytoskeleton in AD.

Chromosome 14 familial Alzheimer's disease: the clinical and neuropathological characteristics of a family with a leucine-->serine (L250S) substitution at codon 250 of the presenilin 1 gene

BACKGROUND

Seven affected members are described from a kindred with autosomal dominant familial Alzheimer's disease associated with a novel mutation in the presenilin 1 (PS1) gene on chromosome 14 that results in a leucine to serine substitution at codon 250 (L250S).

METHOD

Clinical information on the pedigree was collected directly from family members including affected members and their carers and also from hospital records.

RESULTS

Detailed clinical information was available on five members. All had an early age at onset with a median age of 52 (95% confidence interval (95% CI) 49.4-54.9). Age at onset varied between 49 and 56 years, with duration of illness varying between six years and 15 years. Myoclonus, depression, and psychosis were features of this pedigree; seizures were not reported.

CONCLUSIONS

PS1 L250S familial Alzheimer's disease is an early onset form of Alzheimer's disease with clinical features similar to other reported familial Alzheimer's disease pedigrees, except that seizures were absent.

Potential role of muscarinic agonists in Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder and a leading cause of death among the elderly. Recent advances in our understanding of the neurobiology of AD have provided scientific groundwork for the development of potentially more effective and less toxic treatment strategies for the disease. Some of the neuropathological hallmarks of AD include early and extensive degeneration of cortically projecting cholinergic neurons in the basal forebrain, and a reduced number of muscarinic acetylcholine receptors. Of note, neocortical muscarinic receptors of the M1 subtype are relatively preserved in the brains of patients with AD, whereas the presynaptic receptors, which are of the M2 subtype, are reduced in number. Therefore, activation of relatively intact postsynaptic mechanisms by muscarinic M1 receptor-specific agonists could theoretically be more efficacious in the treatment of AD compared with agents (e.g. acetylcholinesterase inhibitors) that predominantly act on dysfunctional presynaptic terminals. The administration of muscarinic agonists can demonstrably enhance cognition and significantly improve some of the disturbing behaviours in patients with AD. Recent advances in our knowledge of the molecular biology of muscarinic receptors, together with a better understanding of signal transduction pathways in AD, are likely to result in the development of receptor-specific muscarinic agonists that are more efficacious and less toxic. Moreover, preliminary evidence concerning the effects of muscarinic agonists on the processing of amyloid precursor protein and the formation of neurofibrillary tangles suggests that these agents might favourably alter the pathobiology of AD.

Increased S100beta in the cerebrospinal fluid of patients with frontotemporal dementia

Levels of S100beta, a calcium-binding protein found in astrocytes, were measured using a sandwich ELISA in the cerebrospinal fluid (CSF) of patients with frontotemporal dementia and Alzheimer's disease and compared with controls. Mean CSF S100beta concentrations were significantly raised in patients with frontotemporal dementia when compared with healthy controls (0.49 +/- 0.28 vs. 0.22 +/- 0.08 ng/ml, P < 0.001). There was no correlation between age at disease onset, disease severity or length of illness. The increased concentration of CSF S100beta seen in frontotemporal dementia may reflect the marked astrocytosis seen in this condition.

Progressive dementia and leucoencephalopathy as the initial presentation of late onset hereditary cystatin-C amyloidosis. Clinicopathological presentation of two cases

Hereditary Cystatin-C Amyloidosis (HCCA) is a genetic disorder in Icelandic families in which a defective cystatin-C amyloid protein is deposited in the walls of small and middle sized arteries. Cerebral vessels are most affected, resulting in recurrent cerebral hemorrhages and infarctions, usually with onset of clinical symptoms in the twenties or thirties and a rapidly deteriorating clinical course. The disease can be diagnosed by a skin biopsy in symptomatic patients. We report two patients (father and daughter) who did not have a known family history of the disorder and presented late in life with a progressive dementia, associated with cerebral hemorrhages in the younger patient. Cerebral MRI and CT scans of this patient showed extensive leukoencephalopathic changes. Brain tissue samples from both patients showed immunohistochemical reaction to cystatin-C in small and medium-sized cerebral arteries and extensive cortical and white matter microinfarctions. The amyloid changes were less severe in the older patient and a colocation of beta-amyloid protein and cystatin-C was observed in addition to neurofibrillary tangles and senile plaques. Subcortical and cortical infarctions were also observed. HCCA may present late in life with progressive dementia as the only clinical manifestation, reflecting a multi-infarct syndrome secondary to the amyloidosis. A coexpression of cystatin-C and beta protein may occur as in other cerebral amyloid disorders, probably as age-specific changes.

Patterns of neuropsychological impairment in dementia of the Alzheimer type and multi-infarct dementia

Patterns of performance on 22 neuropsychological tests were examined in 58 patients with presumed dementia of the Alzheimer type (DAT) and 58 patients with presumed multi-infarct dementia (MID). Few differences between patterns of performance in DAT and MID were found when overall level of performance was taken into account. Within the DAT group, there were some age-related differences in performance that in themselves might support other studies suggesting clinical and neuropathological differences between subtypes of DAT that are related in part to the age at which the condition occurs. However, similar age-related patterns were found in the MID group and the DAT and MID groups did not differ significantly in this respect. Considerable inter-individual variability in pattern of performance was apparent within each group. A proportion of patients were re-assessed 10 months after initial assessment: the extent of decline over time was not predictable from patients' characteristics or test performances at initial assessment. 'De-differentiation' in patterns of impairment, over time or with increasing severity of impairment, was not observed.

Protein folding, nucleation phenomena and delayed neurodegeneration in Alzheimer's disease

This hypothesis attempts to explain how Alzheimer's disease can be both sporadic and autosomal dominant with catastrophic neurodegeneration occurring after decades of normal function. The production of A beta peptide, the subunit of amyloid plaques, from the ubiquitous amyloid precursor protein is discussed. Conformational changes are argued to be crucial to the formation of these amyloid plaques and to their neurotoxicity. Parallels are drawn with prion disease where similarly a normal cellular protein becomes pathogenic once a conformational change is induced. Post-mitotic neurons in the brain are susceptible to this destructive process which is initiated by nucleation phenomena and is then self propagating. An understanding of the conformational changes involved in plaque formation may open new therapeutic avenues in Alzheimer's disease.

Familial dementia with swollen achromatic neurons and corticobasal inclusion bodies: a clinical and pathological study

Clinical, pathological and molecular genetic data are presented in two families in which 15 individuals have developed a progressive dementia. Clinical details are available in 10 individuals, neuropathological data in 2. Affected individuals presented between the ages of 43 and 59 years with personality change or memory loss. All individuals developed a progressive dementia with features of frontal lobe dysfunction. Affected individuals commonly developed additional features which included dysphasia, parkinsonism, limb clumsiness and disequilibrium. Duration to death was between 3 and 13 years. Pathological examination of one individual from each family revealed a combination of features not previously described in a familial dementia. Macroscopic examination revealed lobar atrophy. Microscopy revealed neuronal loss and gliosis with swollen achromatic neurons in the cortex and corticobasal inclusion bodies in the substantia nigra. On clinical assessment these families have many features of Pick's disease but pathological examination reveals features more suggestive of corticobasal degeneration.

Regional cerebral blood flow measured by 99mTc-HMPAO SPECT differs in subgroups of Alzheimer's disease

Alzheimer's disease (AD) is a heterogeneous entity. Identifying AD subtypes might have impact in patients' response to different treatment strategies. We designed a study to examine regional cerebral blood flow (rCBF) in AD subtypes. To identify AD subtypes, we performed a cluster analysis including performance on memory, language, visuospatial, praxic, and executive functions. The rCBF measured by 99mTc-HMPAO SPECT was referred to the cerebellum. We examined 35 patients fulfilling the NINCDS-ADRDA criteria of probable AD and 13 age and sex-matched healthy cognitively intact controls. AD patients were at the early stage of the disease, their mean Mini-Mental Status (MMS) score (S.D.) was 22.5 (3.6). The cluster analysis revealed two AD subgroups: AD1 (N = 12) and AD2 (N = 23). The subgroups did not differ in age, sex, or global clinical severity as assessed by MMS and Brief Cognitive Rating Scale (BCRS). Both subgroups had equally impaired memory. The AD2 group was inferior to the AD1 group on verbal, visuospatial, praxic, and executive functions. The AD1 group showed reduced rCBF ratios in the temporal and parietal cortices and the amygdala compared to controls. The AD2 group differed from controls in the rCBF ratios of frontal, temporal, parietal, occipital, basal ganglia, and amygdaloid regions bilateral and from AD1 in the rCBF ratios of frontal and temporal cortices. In AD patients, the rCBF ratios did not correlate with MMS or BCRS scores. In contrast, several significant correlations were found between decreases rCBF ratios and impairment of memory and other cognitive functions. In conclusion, a cluster analysis on neuropsychological test performance identified two AD subgroups that differed on the neuropsychological profile and on the rCBF in spite of similar global clinical severity.

Deficits in cerebral glucose metabolism demonstrated by positron emission tomography in individuals at risk of familial Alzheimer's disease

In order to establish whether positron emission tomography (PET) can identify metabolic changes in Alzheimer's disease at a presymptomatic stage, we have examined 24 asymptomatic at risk individuals from families with Alzheimer's disease. A significant reduction in global cerebral metabolic rate for glucose was found when compared with 16 age-matched controls. There was also a focal, parieto-temporal deficit similar to, although less extensive than, that found in 18 symptomatic individuals from familial Alzheimer's disease (FAD) pedigrees. Follow up of this cohort will establish whether these metabolic changes relate to a presymptomatic stage of the disease.

Catastrophe, chaos and Alzheimer's disease. The F E Williams Lecture

A model can be developed for familial APP mutation Alzheimer's disease to explain why a patient who is cognitively normal until middle age experiences a catastrophic amyloid deposition, which is to some extent mirrored in the clinical deterioration due to a subtle shift in A beta metabolism. However, the analysis of young onset dementia hardly constitutes the study of 'the suffering and infirmities of old age' which F E Williams' bequest is intended to promote. It remains to be seen whether the models relevant to APP mutation FAD can be applied to Alzheimer's disease of old age, or indeed other degenerative diseases of later life. Such models, however, do provide an alternative to the view that Alzheimer's disease is an incremental process virtually indistinguishable from old age itself. With an incremental linear process, treatment is akin to a war of attention. By contrast, with a catastrophic process the difference between a normal elderly person and a patient with incipient Alzheimer's disease at the start may be minimal, perhaps only a few molecules of extended A beta peptide, but they diverge very rapidly. If treatment can be directed at the metabolic events at the onset then there is a real opportunity for optimism. If ultimately successful, prevention rather than delay becomes a realistic goal, echoing Duc de La Rochefoucauld's desire 'to die as young as possible as late as possible'.

The earliest cognitive change in a person with familial Alzheimer's disease: presymptomatic neuropsychological features in a pedigree with familial Alzheimer's disease confirmed at necropsy

Comprehensive, longitudinal neuropsychological assessments are reported in a person "at risk" from autosomal dominant, necropsy confirmed familial Alzheimer's disease. The first assessment showed a moderately selective verbal memory deficit in the context of mild general intellectual impairment. Subsequent testing showed the progressive deterioration of visual memory and a mild decline of perceptual and spatial skills. Language and literacy skills, however, remained comparatively intact. The neuropsychological profiles obtained at each assessment are presented in profile maps. These permit direct longitudinal comparison of cognitive function, and may serve in the comparison of different potential cases of familial Alzheimer's disease. This case sought medical attention for memory difficulties 26 months after the first neuropsychological assessment. These results mark the first cognitive manifestations in a pedigree with familial Alzheimer's disease which, in this case, were seen presymptomatically. The findings are discussed in relation to neuropsychological studies of affected cases, and in terms of their reflecting the heterogeneous nature of familial Alzheimer's disease.

Lewy bodies in the brain of two members of a family with the 717 (Val to Ile) mutation of the amyloid precursor protein gene

A second member of the original family with the valine to isoleucine substitution at codon 717 of the amyloid precursor protein died after the clinical diagnosis of Alzheimer's disease had been made in life. Neuropathological examination of the brain revealed not only severe Alzheimer type pathology, with senile plaques and neurofibrillary tangles, but also Lewy bodies both in the cortex and brainstem. Lewy bodies also occurred in our first case, thus showing striking similarities in these two members of the same family. The possibility exists that the occurrence of Lewy bodies may not be coincidental, but could be genetically determined: the same genetic abnormality which determines the deposition of beta A4 protein, thus triggering of a chain of events leading to Alzheimer's disease, may result in, or predispose to Lewy body formation.