Limbic lobe involvement in presenile dementia

Frontotemporal lobar degeneration with TAR DNA-binding protein 43 (TDP-43): its journey of more than 100 years

Frontotemporal lobar degeneration (FTLD) with TDP-43-immunoreactive inclusions (FTLD-TDP) is a neurodegenerative disease associated with clinical, genetic, and neuropathological heterogeneity. An association between TDP-43, FTLD and amyotrophic lateral sclerosis (ALS) was first described in 2006. However, a century before immunohistochemistry existed, atypical dementias displaying behavioral, language and/or pyramidal symptoms and showing non-specific FTLD with superficial cortical neuronal loss, gliosis and spongiosis were often confused with Alzheimer's or Pick's disease. Initially this pathology was termed dementia lacking distinctive histopathology (DLDH), but this was later renamed when ubiquitinated inclusions originally found in ALS were also discovered in (DLDH), thus warranting a recategorization as FTLD-U (ubiquitin). Finally, the ubiquitinated protein was identified as TDP-43, which aggregates in cortical, subcortical, limbic and brainstem neurons and glial cells. The topography and morphology of TDP-43 inclusions associate with specific clinical syndromes and genetic mutations which implies different pathomechanisms that are yet to be discovered; hence, the TDP-43 journey has actually just begun. In this review, we describe how FTLD-TDP was established and defined clinically and neuropathologically throughout the past century.

Mapping Neurodegenerative Disease Onset and Progression

Brain networks have been of long-standing interest to neurodegeneration researchers, including but not limited to investigators focusing on conventional prion diseases, which are known to propagate along neural pathways. Tools for human network mapping, however, remained inadequate, limiting our understanding of human brain network architecture and preventing clinical research applications. Until recently, neuropathological studies were the only viable approach to mapping disease onset and progression in humans but required large autopsy cohorts and laborious methods for whole-brain sectioning and staining. Despite important advantages, postmortem studies cannot address in vivo, physiological, or longitudinal questions and have limited potential to explore early-stage disease except for the most common disorders. Emerging in vivo network-based neuroimaging strategies have begun to address these issues, providing data that complement the neuropathological tradition. Overall, findings to date highlight several fundamental principles of neurodegenerative disease anatomy and pathogenesis, as well as some enduring mysteries. These principles and mysteries provide a road map for future research.

Evaluating Behavior in Mouse Models of the Behavioral Variant of Frontotemporal Dementia: Which Test for Which Symptom?

The behavioral variant of frontotemporal dementia (bvFTD) is a neurodegenerative disease affecting people in their early sixties, characterized by dramatic changes in individual and social behavior. Despite the heterogeneity in the presentation of the clinical symptoms of bvFTD, some characteristic changes can be highlighted. Social disinhibition, changes in food preferences as well as loss of empathy and apathy are commonly described. This is accompanied by a characteristic and dramatic atrophy of the prefrontal cortex with the accumulation of protein aggregates in the neurons in this area. Several causative mutations in different genes have been discovered, allowing the development of transgenic animal models, especially mouse models. In mice, attention has been focused on the histopathological aspects of the pathology, but now studies are taking interest in assessing the behavioral phenotype of FTD models. Finding the right test corresponding to human symptoms is quite challenging, especially since the frontal cortex is much less developed in mice than in humans. Although challenging, the ability to detect relevant prefrontal cortex impairments in mice is crucial for therapeutic approaches. In this review, we aim to present the approaches that have been used to model the behavioral symptoms of FTD and to explore other relevant approaches to assess behavior involving the prefrontal cortex, as well as the deficits associated with FTD.

Atrophy in distinct corticolimbic networks in frontotemporal dementia relates to social impairments measured using the Social Impairment Rating Scale

Patients with frontotemporal dementia (FTD) often exhibit prominent, early and progressive impairments in social behaviour. We developed the Social Impairment Rating Scale (SIRS), rated by a clinician after a structured interview, which grades the types and severity of social behavioural symptoms in seven domains. In 20 FTD patients, we used the SIRS to study the anatomic basis of social impairments. In support of hypotheses generated from a prior study of healthy adults, we found that the relative magnitude of brain atrophy in three partially dissociable corticolimbic networks anchored in the amygdala predicted the severity of distinct social impairments measured using the SIRS. Patients with the greatest atrophy in a mesolimbic, reward-related (affiliation) network exhibited the most severe socioemotional detachment, whereas patients with the greatest atrophy in an interoceptive, pain-related (aversion) network exhibited the most severe lack of social apprehension. Patients with the greatest atrophy in a perceptual network exhibited the most severe lack of awareness or understanding of others' social and emotional behaviour. Our findings underscore observations that FTD is associated with heterogeneous social symptoms that can be understood in a refined manner by measuring impairments in component processes subserved by dissociable neural networks. Furthermore, these findings support the validity of the SIRS as an instrument to measure the social symptoms of patients with FTD. Ultimately, we hope it will be useful as a longitudinal outcome measure in natural history studies and in clinical trials of putative interventions to improve social functioning.

Anterior insula degeneration in frontotemporal dementia

The human anterior insula is anatomically and functionally heterogeneous, containing key nodes within distributed speech-language and viscero-autonomic/social-emotional networks. The frontotemporal dementias selectively target these large-scale systems, leading to at least three distinct clinical syndromes. Examining these disorders, researchers have begun to dissect functions which rely on specific insular nodes and networks. In the behavioral variant of frontotemporal dementia, early-stage frontoinsular degeneration begets progressive "Salience Network" breakdown that leaves patients unable to model the emotional impact of their own actions or inactions. Ongoing studies seek to clarify local microcircuit- and cellular-level factors that confer selective frontoinsular vulnerability. The search for frontotemporal dementia treatments will depend on a rich understanding of insular biology and could help clarify specialized human language, social, and emotional functions.

Selective functional, regional, and neuronal vulnerability in frontotemporal dementia

PURPOSE OF REVIEW

The molecular neuroscience revolution has begun to rekindle interest in fundamental neuroanatomy. Blending these disciplines may prove critical to our understanding of neurodegenerative diseases, which target specific anatomical systems. Recent research on frontotemporal dementia highlights the potential value of these approaches.

RECENT FINDINGS

The behavioral variant of frontotemporal dementia leads to progressive social-emotional processing deficits accompanied by anterior cingulate and frontal insular degeneration. These sites form a discrete human neural network and feature a class of layer 5b projection neurons, von Economo neurons, found only in large-brained, socially complex mammals. von Economo neurons have been shown to represent an early target in the behavioral variant of frontotemporal dementia but not in Alzheimer's disease.

SUMMARY

Integrative approaches to selective vulnerability may help clarify neurodegenerative disease pathogenesis.

Frontal paralimbic network atrophy in very mild behavioral variant frontotemporal dementia

BACKGROUND

Behavioral variant frontotemporal dementia (bvFTD) strikes hardest at the frontal lobes, but the sites of earliest injury remain unclear.

OBJECTIVE

To determine atrophy patterns in distinct clinical stages of bvFTD, testing the hypothesis that the mildest stage is restricted to frontal paralimbic cortex.

DESIGN

A bvFTD cohort study.

SETTING

University hospital dementia clinic.

PARTICIPANTS

Patients with bvFTD with Clinical Dementia Rating (CDR) scale scores of 0.5 (n = 15), 1 (n = 15), or 2 to 3 (n = 15) age and sex matched to each other and to 45 healthy controls.

MAIN OUTCOME MEASURES

Magnetic resonance voxel-based morphometry estimated gray matter and white matter atrophy at each disease stage compared with controls.

RESULTS

Patients with a CDR score of 0.5 had gray matter loss in frontal paralimbic cortices, but atrophy also involved a network of anterior cortical and subcortical regions. A CDR score of 1 showed more extensive frontal gray matter atrophy and white matter losses in corpus callosum and brainstem. A CDR score of 2 to 3 showed additional posterior insula, hippocampus, and parietal involvement, with white matter atrophy in presumed frontal projection fibers.

CONCLUSIONS

Very mild bvFTD targets a specific subset of frontal and insular regions. More advanced disease affects white matter and posterior gray matter structures densely interconnected with the sites of earliest injury.

Distinct MRI atrophy patterns in autopsy-proven Alzheimer's disease and frontotemporal lobar degeneration

To better define the anatomic distinctions between Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD), we retrospectively applied voxel-based morphometry to the earliest magnetic resonance imaging scans of autopsy-proven AD (N = 11), FTLD (N = 18), and controls (N = 40). Compared with controls, AD patients showed gray matter reductions in posterior temporoparietal and occipital cortex; FTLD patients showed atrophy in medial prefrontal and medial temporal cortex, insula, hippocampus, and amygdala; and patients with both disorders showed atrophy in dorsolateral and orbital prefrontal cortex and lateral temporal cortex (P(FWE-corr) < .05). Compared with FTLD, AD patients had decreased gray matter in posterior parietal and occipital cortex, whereas FTLD patients had selective atrophy in anterior cingulate, frontal insula, subcallosal gyrus, and striatum (P < .001, uncorrected). These findings suggest that AD and FTLD are anatomically distinct, with degeneration of a posterior parietal network in AD and degeneration of a paralimbic fronto-insular-striatal network in FTLD.

On the multivariate nature of brain metabolic impairment in Alzheimer's disease

We used principal component analysis to decompose functional images of patients with AD in orthogonal ensembles of brain regions with maximal metabolic covariance. Three principal components explained 38% of the total variance in a large sample of FDG-PET images obtained in 225 AD patients. One functional ensemble (PC2) included limbic structures from Papez's circuit (medial temporal regions, posterior and anterior cingulate cortex, thalamus); its disruption in AD patients was related to episodic memory impairment. Another principal component (PC1) illustrated major metabolic variance in posterior cerebral cortices, and patients' scores were correlated to instrumental functions (language and visuospatial abilities). PC3 comprised frontal, parietal, temporal and posteromedial (posterior cingulate and precuneus) cortices, and patients' scores were related to executive dysfunction and global cognitive impairment. The three main metabolic covariance networks converged in the posterior cingulate area that showed complex relationships with medial temporal structures within each PC. Individual AD scores were distributed as a continuum along PC axes: an individual combination of scores would determine specific clinical symptoms in each patient.

Early frontotemporal dementia targets neurons unique to apes and humans

OBJECTIVE

Frontotemporal dementia (FTD) is a neurodegenerative disease that erodes uniquely human aspects of social behavior and emotion. The illness features a characteristic pattern of early injury to anterior cingulate and frontoinsular cortex. These regions, though often considered ancient in phylogeny, are the exclusive homes to the von Economo neuron (VEN), a large bipolar projection neuron found only in great apes and humans. Despite progress toward understanding the genetic and molecular bases of FTD, no class of selectively vulnerable neurons has been identified.

METHODS

Using unbiased stereology, we quantified anterior cingulate VENs and neighboring Layer 5 neurons in FTD (n = 7), Alzheimer's disease (n = 5), and age-matched nonneurological control subjects (n = 7). Neuronal morphology and immunohistochemical staining patterns provided further information about VEN susceptibility.

RESULTS

FTD was associated with early, severe, and selective VEN losses, including a 74% reduction in VENs per section compared with control subjects. VEN dropout was not attributable to general neuronal loss and was seen across FTD pathological subtypes. Surviving VENs were often dysmorphic, with pathological tau protein accumulation in Pick's disease. In contrast, patients with Alzheimer's disease showed normal VEN counts and morphology despite extensive local neurofibrillary pathology.

INTERPRETATION

VEN loss links FTD to its signature regional pattern. The findings suggest a new framework for understanding how evolution may have rendered the human brain vulnerable to specific forms of degenerative illness.

Changes in frontal lobe activity with cognitive therapy for spider phobia

Patients suffering from spider phobia were studied with measurement of regional cerebral blood flow (rCBF) when they were looking at a video recording of living spiders. Six patients were studied before and after cognitive psychotherapy with successful outcome in all cases. On each occasion rCBF was measured under 3 conditions: during rest, during exposure to a video recording of neutral nature scenery, and finally while the patient watched a recording of living spiders. The patients who managed to control their emotional reactions without panicking during spider exposure before treatment showed an rCBF increase in prefrontal cortex, more pronounced in the right hemisphere. Following successful treatment, these patients showed an rCBF decrease in this region. In contrast, patients who reported panic during the initial spider exposure showed hypoactivity in the frontal cortex at that time, and then showed an increase in prefrontal rCBF in the spider challenge after cognitive therapy. The psychological improvement from cognitive therapy thus appears to be associated with activation of prefrontal cortex that varies closely with the demands for self-regulation of emotional reactivity.

Oral reading in dementia

Reading has been thought to consist of three main processing components: the orthographic, phonological, and semantic lexicons. In traditional psycholinguistic models, these components have been treated independently such that the selective dysfunction of one does not necessarily imply the breakdown of another. Recently, it has been proposed that a word's semantic representation is essential to oral reading such that a disturbance within the semantic lexicon will disrupt processing within the orthographic and/or phonological lexicons. From this view, semantic deterioration should lead to fragmentation of the other systems contributing to reading, resulting in a specific pattern of errors during oral reading. This would include (1) a larger than normal advantage for reading words with regular spelling-to-sound correspondence over words with exception spelling, as well as the production of "regularization errors" when reading exception words; and (2) a smaller than normal difference between reading real words and pronounceable nonwords, or pseudowords (PW's). We found that patients with Semantic Dementia generally conformed to these hypothesized patterns of reading difficulty. Despite the presence of a semantic impairment, however, patients with Alzheimer's Disease, Frontotemporal Dementia, and Progressive Non-Fluent Aphasia did not demonstrate these patterns of reading difficulty. Our findings suggest that not all semantic impairments invariably lead to the disruption of the orthographic and phonological lexicons.

Apolipoprotein E genotype and noncognitive symptoms in Alzheimer's disease

BACKGROUND

The apolipoprotein E (ApoE) epsilon 4 allele confers significant risk for Alzheimer's disease and is associated with a greater amyloid burden in the brain. Future treatments may target molecular mechanisms associated with this allele, and it is important to define any phenotypic characteristics that correspond to this genotype. We sought to clarify the relationship between ApoE status and noncognitive symptoms in Alzheimer's disease patients.

METHODS

Possible and probable Alzheimer's disease patients from a clinical trial (n = 605) were assessed with the 10-item Neuropsychiatric Inventory cross-sectionally prior to treatment, and their ApoE genotype was determined. Among the population studied, the following numbers with specific genotypes were studied: 23-2/3, 17-2/4, 209-3/3, 288-3/4, 68-4/4.

RESULTS

When correlations were controlled for the patient's level of cognitive impairment, there was no relationship between epsilon 4 dose and any of the 10 noncognitive symptoms assessed, including psychosis, mood changes, and personality alterations.

CONCLUSIONS

Among patients with comparable disease severity, the epsilon 4 allele does not confer additional psychiatric morbidity.

Alzheimer's disease and oxidative stress: implications for novel therapeutic approaches

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a deadly outcome. AD is the leading cause of senile dementia and although the pathogenesis of this disorder is not known, various hypotheses have been developed based on experimental data accumulated since the initial description of this disease by Alois Alzheimer about 90 years ago. Most approaches to explain the pathogenesis of AD focus on its two histopathological hallmarks, the amyloid beta protein- (A(beta)-) loaded senile plaques and the neurofibrillary tangles, which consist of the filament protein tau. Various lines of genetic evidence support a central role of A(beta) in the pathogenesis of AD and an increasing number of studies show that oxidation reactions occur in AD and that A(beta) may be one molecular link between oxidative stress and AD-associated neuronal cell death. A(beta) itself can be neurotoxic and can induce oxidative stress in cultivated neurons. A(beta) is, therefore, one player in the concert of oxidative reactions that challenge neurons besides inflammatory reactions which are also associated with the AD pathology. Consequently, antioxidant approaches for the prevention and therapy of AD are of central interest. Experimental as well as clinical data show that lipophilic antioxidants, such as vitamin E and estrogens, are neuroprotective and may help patients suffering from AD. While an additional intensive elucidation of the cellular and molecular events of neuronal cell death in AD will, ultimately, lead to novel drug targets, various antioxidants are already available for a further exploitation of their preventive and therapeutic potential. reserved

Single photon emission computed tomography in dementia: relationship of perfusion to cognitive deficits

Sixteen patients with dementia (nine with Alzheimer's disease and seven with multi-infarct dementia) were studied with xenon-133 and hexamethyl-propyleneamine-oxime single photon emission computed tomography (SPECT). Quantification of cerebral blood flow was determined in 16 hemispheric regions of interest. Neuropsychological deficits were assessed with the Mini-Mental State Examination and the Neurobehavior Cognitive Status Examination. Alzheimer's disease patients had symmetric reduction of parietal lobe perfusion; multi-infarct dementia patients had multifocal perfusion deficits. Correlations were demonstrated between cerebral blood flow in the posterior brain regions and performance on tests of language, memory, attention, figure copying, judgment, and similarities. Alzheimer's disease patients exhibited more language impairment than multi-infarct dementia patients. SPECT promises to provide diagnostic information and data relevant to interpretation of neuropsychological deficits.

Physostigmine ameliorates the delusions of Alzheimer's disease

Alzheimer's disease (AD) patients frequently manifest delusions, and the cholinergic deficiency of AD may contribute to this aspect of the psychopathology of the disorder. In a double-blind, crossover study involving two patients, we compared the antidelusional efficacy of physostigmine, an acetylcholinesterase inhibitor, with haloperidol, a widely used neuroleptic agent. Physostigmine ameliorated the delusions and produced fewer side effects. These preliminary observations suggest that the cholinergic deficiency contributes to the occurrence of delusions in AD and cholinergic therapy may have a role in the treatment of the delusional symptoms.

The human entorhinal cortex: normal morphology and lamina-specific pathology in various diseases

The entorhinal territory consists of the entorhinal and transentorhinal regions spreading over the ambient gyrus and anterior portions of the parahippocampal gyrus. The transentorhinal region mediates between the adjoining temporal isocortex laterally and the entorhinal region medially. The entorhinal cortex consists of a molecular layer, followed by an external principal stratum, a cell-sparse lamina dissecans, an internal principal stratum and--within the underlying white matter--a profound cellular layer. The principal strata can each be divided into three layers Pre alpha, beta, gamma, and Pri alpha, beta, gamma. Data obtained from experimental investigations in monkeys reveal that the entorhinal territory serves as a relay station for information from both isocortical association areas and centers of the limbic system. After processing within the entorhinal cortex, this information is transferred to the hippocampal formation via the perforant path. Pathological changes within the entorhinal territory impair this continuous data transfer and contribute to a decline of cognitive functions. Entorhinal involvement associated with impaired cognitive functions is described in cases of Alzheimer's disease, Parkinson's disease, progressive supranuclear palsy, dementia with argyrophilic grains and Huntington's disease.

The distribution of tangles, plaques and related immunohistochemical markers in healthy aging and Alzheimer's disease

Neurofibrillary tangles and senile plaques, together with cells immunoreactive for the Alz-50 antibody (A50-ir cells) or for an antibody against paired helical filaments (PHF-ir cells), and amyloid deposits stained with antibodies against beta-(or A4)-amyloid, have been mapped throughout the ventral forebrains of 25 old people. The cognitive status of each individual was assessed and a "Clinical Dementia Rating" (CDR) assigned, either before death in the Memory and Aging Project of Washington University, or by a postmortem interview, with an appropriate collateral source. The cases studied included 13 nondemented cases (CDR = 0), six very mildly to mildly demented cases (CDR = 0/0.5 to 1) and six more severely demented cases (CDR = 2 to 3). Because even the very mildly demented brains showed substantial pathological change, emphasis was placed on examining the nondemented cases for the earliest changes that could be associated with Alzheimer's disease. Different distributions were found for tangles and plaques. Tangles (and A50-ir and PHF-ir cells) were present in all of the brains examined. In the younger nondemented cases (aged 54 to 63) there were a few affected cells in the anterior olfactory nucleus and the parahippocampal gyrus. In older nondemented cases (aged 73-89) more tangles were found in the same areas, and also in hippocampal field CA1. The very mildly demented cases had many more tangles, but their distribution was similar. Only in the severely demented cases were large numbers of tangles present in the neocortex. In contrast, no plaques (or beta-amyloid immunoreactivity) were found in any of the younger nondemented cases or in four of the eight older nondemented cases. In three older nondemented cases there were a few primitive plaques, which were restricted to localized regions of the neocortex (e.g., a portion of the inferior temporal cortex). In one nondemented case and all of the very mildly to mildly demented cases there were very large numbers of mostly primitive plaques, particularly in the neocortex. With greater severity of dementia there is a shift from primitive to mature plaques. These results were interpreted to imply that the first development of tangles and plaques occurs in different parts of the brain. Tangles appear during aging in the anterior olfactory nucleus, the parahippocampal gyrus and the hippocampus, but are rare in the neocortex except in demented brains. Conversely plaques may develop first in the neocortex. Unlike tangles, plaques are not a consistent feature of aging, at least up to age 80.

Personality alterations in dementia of the Alzheimer type: a three-year follow-up study

Alterations in personality accompany the onset and progression of dementia of the Alzheimer type. Longitudinal investigations of these changes using systematic quantifiable documentation have been infrequent. In this 3-year follow-up study, we report longitudinal observations of changes in personality in dementia of the Alzheimer type. Four response patterns were observed: (1) change at onset with little change as the disease continued, (2) ongoing change as the disorder progressed, (3) no change, and (4) regression of previously more disturbed behaviors. Repeated characterizations of the premorbid personality profile as determined by this inventory were found to be reliable.

Monosymptomatic delusions of parasitosis associated with ischemic cerebrovascular disease

Monosymptomatic delusion of infestation (parasitosis) occur in idiopathic psychoses but have rarely been observed in patients with neurologic or systemic illnesses. A patient was observed in whom the delusion occurred in the presence of demonstrable cerebrovascular disease. The delusional symptoms were contralateral to the principal site of ischemic injury. Delusions of infestation may reflect an acquired neurologic or metabolic disorder, and medical and neurologic evaluation should be pursued in elderly patients presenting with this syndrome.

Psychometric characteristics in patients with frontal lobe degeneration of non-Alzheimer type

Twenty patients, selected from a longitudinal study of patients with presenile and senile dementia, underwent psychometric assessment including semi-structured observations of behaviour in the test situation and examination for dysphasia. The patients were chosen on the basis of post-mortem investigation and showed frontal lobe degeneration (FLD) of non-Alzheimer type in 16 cases and Pick's disease in four cases. The patients are described with reference to cognition, language function, behaviour and emotional reactions in the test situation. The test results were analyzed and compared with psychometric results from other groups of demented patients, above all with Alzheimer's disease. The cognitive dysfunction was less severe in patients with onset of dementia below the age of 56 years as compared to patients with later onset, i.e., 56 years or older. Dysfunction of expressive speech was the most consistent finding in the patients with frontal lobe degeneration, while receptive speech functions were relatively less frequently affected.

Dementia of frontal lobe type

A significant proportion of patients with presenile dementia due to primary cerebral atrophy do not have Alzheimer's disease. One form of non-Alzheimer dementia may be designated as dementia of frontal lobe type (DFT), on the basis of a characteristic neuropsychological picture suggestive of frontal lobe disorder, confirmed by findings on single photon emission tomography. The case histories of seven patients exemplify the disorder: a presentation of social misconduct and personality change, unconcern and disinhibition, in the presence of physical well-being and few neurological signs. Assessment revealed economic and concrete speech with verbal stereotypes, variable memory impairment, and marked abnormalities on tasks sensitive to frontal lobe function. Visuo-spatial disorder was invariably absent. Comparisons of DFT and Alzheimer patients revealed qualitative differences in clinical presentation, neurological signs, profile of psychological disability, electroencephalography, single photon emission tomography and demography. DFT, which may represent forms of Pick's disease, may be more common than is often recognised.

Axonal and transneuronal transport in the transmission of neurological disease: potential role in system degenerations, including Alzheimer's disease

Neurons depend upon the processes of axonal and transneuronal transport for intra- and intercellular communication and trophic support. Experimental studies in the last decade have elucidated the mechanisms underlying these processes, and provided evidence for their role in the spread of viral and toxic diseases through the nervous system. Recent advances in neuroanatomy, and in the pathological study of certain degenerative conditions, such as Alzheimer's disease, suggest that the same principles may underlie the anatomical specificity of cell loss in a variety of system degenerations. In Alzheimer's disease, as well as in olivo-ponto-cerebellar atrophy, progressive supranuclear palsy, amyotrophic lateral sclerosis, primary autonomic failure of the Shy-Drager type, and other system degenerations, the main feature that marks the affected populations of neurons is their anatomical interconnectivity. We consider here the possibility that, in these conditions, the processes of axonal and transneuronal transport may subserve the transmission from neuron to neuron of a toxic or infectious agent, or alternatively that the diseases may result from the failure of normal transport of a trophic agent. This hypothesis not only provides a unifying framework in which to view a variety of seemingly disparate conditions, but also suggests certain approaches to identifying the causative agents.

Frontal lobe degeneration of non-Alzheimer type. II. Clinical picture and differential diagnosis

In a longitudinal prospective study of dementia, 158 patients were investigated post mortem. Sixteen patients were classified as frontal lobe dementia (FLD) of non-Alzheimer type and four cases as Pick's disease. Positive heredity for dementia was reported in 50% of these cases compared to 30% in a reference group of patients with Alzheimer's disease (AD). The typical clinical picture in FLD and Pick's disease was that of a slowly progressive dementia, at an early stage dominated by personality change, lack of insight, disinhibition, and later on stereotypy and increased apathy. There was also a progressive dynamic aphasia ending in mutism and amimia. Memory and spatial functions were comparatively spared. Disinhibition, oral/dietary hyperactivity, and echolalia were more consistently found in Pick's disease compared to FLD. The differential diagnosis against AD, cerebrovascular dementia, and other degenerative dementias and against affective disorders and psychotic reactions are discussed.

The progression of personality changes in senile dementia of the Alzheimer's type

Passive, agitated, and self-centered behavioral changes were noted on initial evaluation in two-thirds, one-third, and one-third, respectively, of subjects with mild senile dementia of the Alzheimer's type (SDAT). Over a 50-month follow-up period, the percentage of patients who exhibited agitated and self-centered behaviors doubled. The percentage of subjects who demonstrated all three behavioral changes increased from 11% at entry to the study (mild SDAT) to over 50% when the dementia had reached a severe stage. The presence of personality changes at a mild stage of dementia did not predispose subjects to more rapid progression to a more advanced stage of illness.

Behavioral changes in patients with mild senile dementia of the Alzheimer's type

Behavioral changes in 44 subjects with well-characterized mild senile dementia of the Alzheimer's type (SDAT) and 16 subjects with only questionable SDAT were compared to a control group of 58 subjects. Answers to both open-ended questions and personality items from the Blessed Dementia Scale were examined. Seventeen items were classified into seven categories by factor analysis and then further categorized into four clinically useful groups: passive, agitated, self-centered, and suspicious. Over 75% of subjects with mild SDAT had behavioral changes compared to 10% of controls. Passive symptoms were the most common, occurring in two-thirds of mild SDAT subjects. Agitated and self-centered symptoms were also common, occurring half as frequently as passive symptoms. Passive symptoms occurred alone in 25% of those with mild SDAT, whereas passive symptoms, together with agitated and/or self-centered symptoms, were present in 11-16% of subjects with mild SDAT. Agitated or self-centered symptoms rarely occurred alone. Characterizing the behavioral symptoms of SDAT is important for their clinical implications and for an approach to understanding brain-behavioral relationships.

Intravenous physostigmine treatment of Alzheimer's disease evaluated by psychometric testing, regional cerebral blood flow (rCBF) measurement, and EEG

Ten patients with Alzheimer's disease were treated with intravenous infusion of physostigmine for 2 h. The acute effects on cognitive function, regional cerebral blood flow, and EEG were compared to placebo (isotonic glucose) using a double-blind cross-over design. Physostigmine causes a limited improvement of psychomotor performance and EEG and an increase of blood flow in the most severely affected cortical areas, predominantly in an early phase of Alzheimer's disease.

Dementia in movement disorders

Of all the movement disorders, Huntington's disease has been most consistently associated with dementia, while it is only over the last decade that intellectual cognitive decline have been recognized as common features of Parkinson's disease. It is now known that the pathology in these two conditions reflects differential involvement of the striatum. The Huntington lesion is primarily in the caudate, while the Parkinson lesion preferentially affects the putamen. Both conditions have more diffuse pathology, and dementia may also occur in a wide range of other extrapyramidal diseases, such as progressive supranuclear palsy, the parkinsonism-dementia complex of Guam, and certain spinocerebellar degenerations. Clinicopathological correlations will be reviewed in these disorders of primarily subcortical pathology, and comparisons will be made with Alzheimer's disease, a disorder of predominantly cortical pathology.

Neuropsychological syndromes in presenile dementia due to cerebral atrophy

In a prospective study of 24 patients with presenile dementia associated with cerebral atrophy, clinical and psychological characteristics of patients' disorder were examined in relation to pathological and chemical findings obtained from tissue analysis following cerebral biopsy. The histological features of Alzheimer's disease were found in 75% of cases, but not in 25%. Distinctive patterns of neuropsychological breakdown emerged allowing clinical grouping of patients. While clinical patterns were helpful in differentiating Alzheimer's disease from non-Alzheimer's disease, there was not an absolute concordance between clinical and patho-chemical groupings. The findings, which support the notion that the "cerebral atrophies" represent a heterogeneous group of conditions, have relevance for the clinical diagnosis of presenile dementia.

On the pathogenesis and therapy of dementia of the Alzheimer type: some neuropathological, biochemical, genetic and pharmacotherapeutic considerations

The extensive literature on dementia of Alzheimer type (DAT) testifies to the enormous progress achieved in the clinical and biochemical delineation of this disease. Newly developed laboratory and imaging techniques are also being applied to the diagnosis of DAT. Nevertheless, unequivoval diagnosis still relies primarily on morphological data from biopsy or autopsy. An overview is presented of major morphological changes occurring at different levels of organization in the central nervous system (CNS) in DAT. Currently formulated etiopathogenic hypotheses of DAT are reviewed and discussed in the context of morphological alterations. Some of the recombinant DNA methods, that are currently available for gene analysis, are described. Some approaches for studying Alzheimer specific genes using the above methods have been suggested. Finally, a critical overview of the current pharmacotherapeutic armamentarium used in DAT and senile dementia is presented. The efficacy, side effects, and the main mechanisms of action of the two categories of drug therapy -supposed etiopathogenic and symptomatic- are presented.

Dementia of the Alzheimer type. An inventory of diagnostic clinical features

An Inventory presenting characteristics useful in the clinical identification of dementia of the Alzheimer type (DAT) is presented. The Inventory includes aphasia, amnesia, abnormal cognition and visuospatial skills, inappropriate lack of concern, and normal motor functions. In a retrospective study of 50 consecutive dementia patients, the DAT Inventory correctly identified 100% of DAT subjects and 94% of non-DAT cases. Utilization of positive criteria can aid in the identification of DAT and can facilitate recognition of treatable illnesses masquerading as DAT.

Brain changes in dementia of Alzheimer's type relevant to new imaging diagnostic methods

The aim of the article is to correlate grey and white matter changes and their topography to the results of modern methods for brain imaging such as CT, rCBF, PET, SPECT and NMR in Alzheimer's type of dementia. The findings are based on the study of a large material investigated thoroughly patho-anatomically. The findings are correlated with psychiatric and neurophysiologic follow-up studies. The degenerative grey matter process shows a regionally varying accent according to a pattern which is consistent and typical for the disease. This corresponds to metabolic changes on rCBF, PET and SPECT and thereby becomes of diagnostic value. This pattern is largely symmetric. Metabolic asymmetries have however been reported on PET scans. In this context individual variations of the topographic degenerative brain pattern and normal anatomical brain asymmetries are of interest. The white matter however also frequently shows changes, in particular loss of myelin and axons and a mild gliosis, slight in 1/3 of the cases and severe in an additional 1/3. These changes cause a decrease of density in the centrum semiovale correlating to lipid depletion. They may also influence the ventricular shape and size, of interest in CT or NMR studies. Also here variations in ventricular shape, normal and such due to pathological processes unrelated to the Alzheimer disease, may cause confusion, regarding degree of atrophy and even type of brain process. Such factors should be considered in the interpretation of non-invasive brain studies.

Multiple biochemical deficits in both gray and white matter of Alzheimer brains

A biochemical investigation of 21 brains from patients with dementia of Alzheimer type (AD/SDAT) and 22 brains from controls was made. In the normal brains 5-hydroxytryptamine (5-HT), noradrenaline (NA) and dopamine (DA) were reduced with age while their metabolites were not reduced. In the brains from the Alzheimer patients the examination of gray matter (caudate nucleus and hippocampus) showed a significant reduced activity of choline-acetyl transferase (CAT) and a reduction of acetylcholinesterase (AChE) that bordered significance in the hippocampus. In the brains from the Alzheimer patients a disturbance was found in the 5-HT system in the form of reduced levels of 5-HT and 5-hydroxyindolacetic acid (5-HIAA). The catecholamine systems were also disturbed but to a less extent. In the 5-HT and DA systems the active amines as well as the metabolites were reduced in the brains from patients with AD/SDAT indicating not only a possible neuronal loss but also an incapacity of the remaining neurons to compensate for the loss by an increased turnover. The lipid content was slightly reduced in gray matter of the demented brains. In white matter there was a more severe reduction of the lipids and in this tissue also the cerebrosides and sulfatides were reduced. It is concluded that in brains from patients with AD/SDAT there are multiple biochemical deficits in gray as well as in white matter. The changes in white matter may be of pathogenetic importance in subgroups of AD/SDAT.

On diagnosis of dementia: psychometric investigation and clinical psychiatric evaluation in relation to verified diagnosis

Patients with early as well as manifest dementia were studied in a longitudinal way with psychometric and psychiatric methods. Tests such as vocabulary, attention test, block design test, verbal and spatial memory tests, reaction time test and examination for aphasia were used as well as a qualitative analysis of behaviour and personality. The differential diagnosis of Alzheimer's disease, Pick's disease and other dementias with fronto-temporal degeneration and multi-infarct dementia was based on diagnostic rating scales. Differences in cognitive profiles, qualities of behaviour and scores on combinations of psychiatric rating scales were identified for pathoanatomically verified cases with Alzheimer's disease, fronto-temporal degeneration and multi-infarct dementia.

Anatomical correlates of the distribution of the pathological changes in the neocortex in Alzheimer disease

The numbers and distribution of the neurofibrillary tangles and neuritic plaques have been determined in several areas of the neocortex in brains affected by various degrees of severity of Alzheimer disease. The homotypical cortex of the "association" areas of the temporal, parietal, and frontal lobes are severely involved, whereas the motor, somatic sensory, and primary visual areas are virtually unaffected. The neurofibrillary tangles are mainly in the supra- and infragranular layers, particularly in layers III and V. In all areas except area 18 in the occipital lobe, there are approximately twice as many tangles in layer V as in layer III. The tangles are arranged in definite clusters, and those in the supra- and infragranular layers are in register. The neuritic plaques occur in all layers but predominantly affect layers II and III and do not show clustering. These data on the severity of the pathological involvement in different areas of the neocortex and the laminar distribution and the clustering of the tangles support the suggestion that the pathological changes in Alzheimer disease affect regions that are interconnected by well-defined groups of connections and that the disease process may extend along the connecting fibers. The invariable and severe involvement of the olfactory areas of the brain in this disease is in striking contrast to the minimal changes in the somatic sensory and primary visual areas and raises the possibility that the olfactory pathway may be initially involved.

The neuropathology of amnesia

Relations between brain damage and memory disturbance are outlined with emphasis on the so-called amnesic syndrome. Following a brief introduction into forms of memory and memory failures, the basic causes of brain damaage (with relevance to amnestic failures) are described. Thereafter, the two best-known forms of brain damage-amnesia relations are reviewed: the consequences of damage to medial temporal lobe structures and to diencephalic regions. For the cases with medial temporal lobe damage, evidence is reported in greater detail for H.M., who has been examined more than any other amnesic patient for more than 30 years now, as a considerable amount of literature has accumulated on his behavior in diverse situations. Other cases with more or less circumscribed damage to medial temporal lobe structures are reviewed so as to outline criteria for or against the hypothesis that there are regions within the medial temporal lobe whose damage might be critical for the amnesic syndrome. Two cases of diencephalic amnesia are summarized in particular (cases of Mair et al., 1979) as they have received extensive neuropsychological and neuropathological investigation. Other cases with, for example, Korsakoff's disease are reviewed, as well as cases with diencephalic, or combined mesencephalic-diencephalic damage without nutritional causes. A third group of patients with massive, but still selective amnesic disturbances are then described: cases of basal forebrain damage, followed by descriptions of Alzheimer's disease which has similarities in the underlying neuropathology. This leads over to cases with more generalized intellectual deteriorations (dementia), which may have developed on the basis of primarily cortical damage or damage principally to basal ganglia structures. After reviewing cases with mainly material-specific memory failures--usually as a consequence of restricted neocortical damage--a separate section follows on patients in whom retrograde amnesia is the prominent symptom. The contribution of animal models of human amnesia is critically reviewed and discrepancies are analyzed between human and animal memory disturbances. This section emphasizes the value of investigating inter-dependencies between brain structures by pointing out that relations between memory disturbances and brain damage may be more complicated than apparent from a simple structure-function assignment. This aspect is further followed up in the conclusions.

Alzheimer's disease and senile dementia: biochemical characteristics and aspects of treatment

Alzheimer's disease (AD) and senile dementia (SD) are often classified together, but there are genetic, biochemical, neuropathological and clinical arguments for separating them. The well-known Alzheimer lesions in the brains of patients with AD and SD are described, as is the loss of neurons in the locus coeruleus. White matter changes in brains from patients with dementia are discussed and related to AD and SD. Biochemical changes in brains of patients with AD and SD include reduced activity of acetylcholinesterase (AChE) and choline-acetyltransferase (CAT), indicating reduced activity in the acetylcholinergic system. There is also, however, reduced activity in the dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) system. The active amines are decreased while the end metabolites are decreased to a lesser extent or normal. The levels of the active amines are thought to reflect the number of neurons, while the levels of end metabolites reflect the rate of turnover in the system. 3-Methoxy-4-hydroxyphenylglycol (MHPG) is increased to levels above normal, which may indicate an increased rate of turnover in the NA system. Monoamine oxidase B (MAO-B), which is increased in advanced age, is further increased in patients with AD and SD. It is assumed that this enzyme is localized in extraneuronal tissue, and therefore the increase may reflect a gliosis. In brains from patients with AD and SD neuropeptides are also studied. Only somatostatin and substance P, however, seem to be reduced, indicating selective damage to the neuropeptides. The biochemical changes can be given pathogenetic importance.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of dementia patients by a WAIS profile related to central cholinergic deficiencies

Sixty-two patients were classified as having Alzheimer-type dementia (AD) or multi-infarct dementia (MID) on the basis of clinical criteria. Protocols from the Wechsler Adult Intelligence Scale (WAIS) were scored according to a formula reported by Fuld to reflect the effects of scopolamine administration in young adults. The formula correctly classified 13 of 23 AD patients and 37 of 39 MID patients. The formula was similar to Wechsler's deterioration quotient, which produced a greater number of false positives. The formula did not appear to be biased by age, sex, or severity of impairments. Results suggest that the neuropsychological investigation of AD which emphasizes the deficiencies in cholinergic neurotransmission may be a fruitful avenue of further investigation.

Biochemical changes in dementia disorders of Alzheimer type (AD/SDAT)

In postmortem investigations of patients with dementia of Alzheimer type (AD/SDAT) (n = 14) the brain weight was significantly reduced when compared to controls (n = 16). In four AD/SDAT-brain parts investigated the concentrations of 5-hydroxy-tryptamine and noradrenaline were significantly reduced while 3-methoxy-4-hydroxyphenylglycol was significantly increased. In the caudate nucleus of the AD/SDAT-brains the concentrations of dopamine and homovanillic acid were significantly reduced. The activity of monoamine oxidase B was increased suggesting a proliferation of extra neuronal tissue in the AD/SDAT-brains. The activity of choline acetyl transferase was reduced in the four brain parts investigated, showing a general reduction in the acetylcholine system in the AD/SDAT-brains. The ganglioside concentration was significantly reduced suggesting a reduced density of nerve endings in the demented brains. The AD/SDAT-group was according to rating scales severely demented. Patients with an early onset of the dementia disease were more severely intellectually reduced and had more pronounced biochemical disturbances than those with a late onset of the dementia.

Thalamic mediodorsal nucleus and memory: a critical evaluation of studies in animals and man

Following a general description of the anatomical organization of the thalamic mediodorsal nucleus (MD) of animals and man, the involvement of this nucleus in the processing of memory related information has been evaluated by reviewing stimulation, electrophysiological, and lesion studies in animals, and by reviewing research on induced lesions, degenerative changes and vascular damage of MD in humans. Neither the results from animal experiments nor those from studies on humans provide clear-cut evidence for a specific, memory related role of MD. However, the findings here presented do support the theory that MD is one of several, possible memory related relay stations. While therapeutically induced and circumscribed lesions of MD rarely result in long-lasting memory deficits, pathological processes in MD are more likely to be followed by severe memory disturbances if one or more particular structures in addition to MD are included in the lesioned regions. Consequently, it is emphasized that only the disruption of more than one site along memory related pathways will result in severe and enduring memory deficits. To account for apparent inter-species differences in the involvement of MD in memory related processes, it has been argued that MD and its principal cortical target region might basically be involved in arousal and emotional processes, but that for primates and especially for man the phylogenetically young parvocellular sector of MD and its cortical projection region, the dorsolateral prefrontal cortex, are furthermore involved in memory functions, which are modulated by emotional factors via the rest of MD and the prefrontal cortex.

Differential diagnosis of presenile dementia on clinical grounds

Fifty-seven patients were studied for differential diagnosis between dementias. Three rating-scales were used for identification of Alzheimer's disease (AD), Pick's disease (PD) and multi-infarct dementia (MID). Their validity was tested against verified diagnoses in 28 patients. The rating-scale of ischemic score consisting of 13 items such as abrupt onset, stepwise progression, fluctuating course, history of strokes and neurological symptoms and signs, identifies patients with MID. This can also be achieved by the two rating-scales for diagnosis of AD (12 items) and PD (9 items), which, however, can also be used for the differentiation between these two dementias. The rating-scale for diagnosis of AD contains clinical features such as early spatial disorientation, apraxia, aphasia, agnosia, logoclonia and increased muscular tension. The rating-scale for PD contains i.a. early loss of insight, early signs of disinhibition, echolalia, mutism and amimia. The results show that the differentiation between the major types of presenile dementia can be achieved by a systematic rating of the clinical features.

Regional pattern of degeneration in Alzheimer's disease: neuronal loss and histopathological grading

The various structural components of the cortical degeneration of Alzheimer's disease were defined and graded. The severity of the degenerative process was thus mapped in different cortical areas where neuronal numbers and cortical width were also measured and compared with controls. Contrary to the general opinion that the degenerative process is rather uniformly diffuse, though accentuated in the medial temporal and frontal cortex, we found a consistent and more elaborate pattern with clearcut regional differences. Thus the degeneration involved, besides basal medial temporal limbic areas, the posterior cingulate gyrus and superior parietal lobule particularly, with somewhat less marked changes in the inferior parietal lobule and inferior temporal gyri. The sensorimotor, calcarine and anterior cingulate areas of the cortex were notably spared until very late stages. This regionally variable severity of the degeneration was also paralleled by a regionally varying reduction in neuronal numbers and cortical width, and agrees with our previously published results of a regional pattern which closely correlates with clinical parameters, including symptom pattern and regional cerebral blood flow alterations.

Amnestic-confabulatory syndrome in hydrocephalic dementia and Korsakoff's psychosis in alcoholism

The clinical course of six alcoholics with Korsakoff's psyter shunt operation. The initial clinical state as well as the symptom improvement showed important similarities between the Korsakoff group and the hydrocephalic dementia group, who improved after shunt operation. Fantastic confabulation and appraxia were only observed in the hydrocephalic dementia group. Psychometrically, both groups showed a similar degree of improvement of the initially impaired verbal memory while only the hydrocephalic dementia group showed impairment of spatial abilities indicating a constructional apraxia. It is suggested that the similarities of the two conditions are related to dysfunction of diencephalic and temporal-limbic structures. The constructional and general apraxia as well as the fantastic confabulation in hydrocephalic dementia indicate a cortical, especially frontal cortical, dysfunction in this disorder.