Dementia in hippocampal sclerosis resembles frontotemporal dementia more than Alzheimer disease

Limbic-predominant age-related TDP-43 encephalopathy (LATE-NC): Co-pathologies and genetic risk factors provide clues about pathogenesis

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is detectable at autopsy in more than one-third of people beyond age 85 years and is robustly associated with dementia independent of other pathologies. Although LATE-NC has a large impact on public health, there remain uncertainties about the underlying biologic mechanisms. Here, we review the literature from human studies that may shed light on pathogenetic mechanisms. It is increasingly clear that certain combinations of pathologic changes tend to coexist in aging brains. Although "pure" LATE-NC is not rare, LATE-NC often coexists in the same brains with Alzheimer disease neuropathologic change, brain arteriolosclerosis, hippocampal sclerosis of aging, and/or age-related tau astrogliopathy (ARTAG). The patterns of pathologic comorbidities provide circumstantial evidence of mechanistic interactions ("synergies") between the pathologies, and also suggest common upstream influences. As to primary mediators of vulnerability to neuropathologic changes, genetics may play key roles. Genes associated with LATE-NC include TMEM106B, GRN, APOE, SORL1, ABCC9, and others. Although the anatomic distribution of TDP-43 pathology defines the condition, important cofactors for LATE-NC may include Tau pathology, endolysosomal pathways, and blood-brain barrier dysfunction. A review of the human phenomenology offers insights into disease-driving mechanisms, and may provide clues for diagnostic and therapeutic targets.

Characterization of hippocampal sclerosis of aging and its association with other neuropathologic changes and cognitive deficits in the oldest-old

Hippocampal sclerosis of aging (HS-A) is a common age-related neuropathological lesion characterized by neuronal loss and astrogliosis in subiculum and CA1 subfield of hippocampus. HS-A is associated with cognitive decline that mimics Alzheimer's disease. Pathological diagnosis of HS-A is traditionally binary based on presence/absence of the lesion. We compared this traditional measure against our novel quantitative measure for studying the relationship between HS-A and other neuropathologies and cognitive impairment. We included 409 participants from The 90+ study with neuropathological examination and longitudinal neuropsychological assessments. In those with HS-A, we examined digitized H&E and LFB stained hippocampal slides. The length of HS-A in each subfield of hippocampus and subiculum, each further divided into three subregions, was measured using Aperio eSlide Manager. For each subregion, the proportion affected by HS-A was calculated. Using regression models, both traditional/binary and quantitative measures were used to study the relationship between HS-A and other neuropathological changes and cognitive outcomes. HS-A was present in 48 (12%) of participants and was always focal, primarily affecting CA1 (73%), followed by subiculum (9%); overlapping pathology (subiculum and CA1) affected 18% of individuals. HS-A was more common in the left (82%) than the right (25%) hemisphere and was bilateral in 7% of participants. HS-A traditional/binary assessment was associated with limbic-predominant age-related TDP-43 encephalopathy (LATE-NC; OR = 3.45, p < 0.001) and aging-related tau astrogliopathy (ARTAG; OR = 2.72, p = 0.008). In contrast, our quantitative approach showed associations between the proportion of HS-A (CA1/subiculum/combined) and LATE-NC (p = 0.001) and arteriolosclerosis (p = 0.005). While traditional binary assessment of HS-A was associated with impaired memory (OR = 2.60, p = 0.007), calculations (OR = 2.16, p = 0.027), and orientation (OR = 3.56, p < 0.001), our quantitative approach revealed additional associations with impairments in language (OR = 1.33, p = 0.018) and visuospatial domains (OR = 1.37, p = 0.006). Our novel quantitative method revealed associations between HS-A and vascular pathologies and impairment in cognitive domains that were not detected using traditional/binary measures.

Limbic-Predominant Age-Related TDP-43 Encephalopathy: LATE-Breaking Updates in Clinicopathologic Features and Biomarkers

PURPOSE OF REVIEW

Limbic-predominant age-related TDP-43 encephalopathy (LATE) is a recently defined neurodegenerative disease characterized by amnestic phenotype and pathological inclusions of TAR DNA-binding protein 43 (TDP-43). LATE is distinct from rarer forms of TDP-43 diseases such as frontotemporal lobar degeneration with TDP-43 but is also a common copathology with Alzheimer's disease (AD) and cerebrovascular disease and accelerates cognitive decline. LATE contributes to clinicopathologic heterogeneity in neurodegenerative diseases, so it is imperative to distinguish LATE from other etiologies.

RECENT FINDINGS

Novel biomarkers for LATE are being developed with magnetic resonance imaging (MRI) and positron emission tomography (PET). When cooccurring with AD, LATE exhibits identifiable patterns of limbic-predominant atrophy on MRI and hypometabolism on 18F-fluorodeoxyglucose PET that are greater than expected relative to levels of local AD pathology. Efforts are being made to develop TDP-43-specific radiotracers, molecularly specific biofluid measures, and genomic predictors of TDP-43. LATE is a highly prevalent neurodegenerative disease distinct from previously characterized cognitive disorders.

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.

Hippocampal Sclerosis in Frontotemporal Dementia: When Vascular Pathology Meets Neurodegeneration

Hippocampal sclerosis (HS) is a common neuropathological finding and has been associated with advanced age, TDP-43 proteinopathy, and cerebrovascular pathology. We analyzed neuropathological data of an autopsy cohort of early-onset frontotemporal dementia patients. The study aimed to determine whether in this cohort HS was related to TDP-43 proteinopathy and whether additional factors could be identified. We examined the relationship between HS, proteinopathies in frontotemporal cortices and hippocampus, Alzheimer disease, cerebrovascular changes, and age. We confirmed a strong association between HS and hippocampal TDP-43, whereas there was a weaker association between HS and frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP). Nearly all of the FTLD-TDP cases had TDP-43 pathology in the hippocampus. HS was present in all FTLD-TDP type D cases, in 50% of the FTLD-TDP A cohort and in 6% of the FTLD-TDP B cohort. Our data also showed a significant association between HS and vascular changes. We reviewed the literature on HS and discuss possible pathophysiological mechanisms between TDP-43 pathology, cerebrovascular disease, and HS. Additionally, we introduced a quantitative neuronal cell count in CA1 to objectify the semiquantitative visual appreciation of HS.

Hippocampal Sclerosis, Argyrophilic Grain Disease, and Primary Age-Related Tauopathy

PURPOSE OF REVIEW

Hippocampal sclerosis, argyrophilic grain disease, and primary age-related tauopathy are common Alzheimer disease mimics that currently lack clinical diagnostic criteria. Increased understanding of these pathologic entities is important for the neurologist who may encounter patients with an unusually slowly progressive degenerative dementia that may appear to meet criteria for Alzheimer disease but who progress to develop symptoms that are unusual for classic Alzheimer disease RECENT FINDINGS: Hippocampal sclerosis has traditionally been associated with hypoxic/ischemic injury and poorly controlled epilepsy, but it is now recognized that hippocampal sclerosis may also be associated with a unique degenerative disease of aging or may be an associated pathologic finding in many cases of frontotemporal lobar degeneration. Argyrophilic grain disease has been recognized as an enigma in the field of pathology for over 30 years, but recent discoveries suggest that it may overlap with other tau-related disorders within the spectrum of frontotemporal lobar degeneration. Primary age-related tauopathy has long been recognized as a distinct clinical entity that lies on the Alzheimer pathologic spectrum, with the presence of neurofibrillary tangles that lack the coexistent Alzheimer plaque development; thus, it is thought to represent a distinct pathologic entity.

SUMMARY

Despite advances in dementia diagnosis that suggest that we have identified and unlocked the mysteries of the major degenerative disease states responsible for cognitive decline and dementia in the elderly, diseases such as hippocampal sclerosis, argyrophilic grain disease, and primary age-related tauopathy demonstrate that we remain on the frontier of discovery and that our diagnostic repertoire of diseases responsible for such clinical symptoms remains in its infancy. Understanding such diagnostic confounds is important for the neurologist in assigning appropriate diagnoses and selecting appropriate therapeutic management strategies for patients with mild cognitive impairment and dementia.

Hippocampal Sclerosis in the Oldest Old: A Finnish Population-Based Study

Background:

There are only few population-based studies that have systemically investigated the prevalence of hippocampal sclerosis (HS) in the very old. The frequency of unilateral versus bilateral HS has been rarely studied.

Objective:

We investigated the prevalence and laterality of HS and its association with other neurodegenerative and vascular pathologies in a population-based sample of very elderly. Furthermore, the concomitant presence of immunoreactivity for TDP-43, p62, and HPtau was studied.

Methods:

The population-based Vantaa 85+ study includes all inhabitants of the city of Vantaa, who were >85 years in 1991 (n = 601). Neuropathological assessment was possible in 302 subjects. Severity of neuronal loss of CA sectors and subiculum was determined bilaterally by HE- staining. Immunohistochemistry performed using antibodies for TDP-43, p62, and HPtau.

Results:

Neuronal loss and pathological changes in the hippocampus sector CA1 and subiculum were observed in 47 of the 302 individuals (16%), and 51% of these changes were bilateral. HS without comorbid neurodegenerative pathology was found in 1/47 subjects with HS (2%). Dementia (p < 0.001) and TDP-43 immunopositivity of the granular cell layer of the dentate fascia (p < 0.001) were strongly associated with HS. The CERAD score, immunopositivity for HPtau and p62 in the granular cell layer of the fascia dentate were also associated.

Conclusion:

HS is prevalent (16%) in the oldest old population, but HS without any comorbid neurodegenerative pathology is rare. The high frequency of unilateral HS (49%) implied that bilateral sampling of hippocampi should be routine practice in neuropathological examination.

"New Old Pathologies": AD, PART, and Cerebral Age-Related TDP-43 With Sclerosis (CARTS)

The pathology-based classification of Alzheimer's disease (AD) and other neurodegenerative diseases is a work in progress that is important for both clinicians and basic scientists. Analyses of large autopsy series, biomarker studies, and genomics analyses have provided important insights about AD and shed light on previously unrecognized conditions, enabling a deeper understanding of neurodegenerative diseases in general. After demonstrating the importance of correct disease classification for AD and primary age-related tauopathy, we emphasize the public health impact of an underappreciated AD "mimic," which has been termed "hippocampal sclerosis of aging" or "hippocampal sclerosis dementia." This pathology affects >20% of individuals older than 85 years and is strongly associated with cognitive impairment. In this review, we provide an overview of current hypotheses about how genetic risk factors (GRN, TMEM106B, ABCC9, and KCNMB2), and other pathogenetic influences contribute to TDP-43 pathology and hippocampal sclerosis. Because hippocampal sclerosis of aging affects the "oldest-old" with arteriolosclerosis and TDP-43 pathologies that extend well beyond the hippocampus, more appropriate terminology for this disease is required. We recommend "cerebral age-related TDP-43 and sclerosis" (CARTS). A detailed case report is presented, which includes neuroimaging and longitudinal neurocognitive data. Finally, we suggest a neuropathology-based diagnostic rubric for CARTS.

Hippocampal Sclerosis of Aging Can Be Segmental: Two Cases and Review of the Literature

Hippocampal sclerosis of aging (HS-Aging) is a neurodegenerative disease that mimics Alzheimer disease (AD) clinically and has a prevalence rivaling AD in advanced age. Whereas clinical biomarkers are not yet optimized, HS-Aging has distinctive pathological features that distinguish it from other diseases with "hippocampal sclerosis" pathology, such as epilepsy, cerebrovascular perturbations, and frontotemporal lobar degeneration. By definition, HS-Aging brains show neuronal cell loss and gliosis in the hippocampal formation out of proportion to AD-type pathology; it is strongly associated with aberrant TDP-43 pathology and arteriolosclerosis. Here, we describe 2 cases of "segmental" HS-Aging in which "sclerosis" in the hippocampus was evident only in a subset of brain sections by hematoxylin and eosin (H&E) stain. In these cases, TDP-43 pathology was more widespread on immunostained sections than the neuronal cell loss and gliosis seen in H&E stains. The 2 patients were cognitively intact at baseline and were tracked longitudinally over a decade using cognitive studies with at least 1 neuroimaging scan. We discuss the relevant HS-Aging literature, which indicates the need for a clearer consensus-based delineation of "hippocampal sclerosis" and TDP-43 pathologies in aged subjects.

Hippocampal sclerosis dementia with the C9ORF72 hexanucleotide repeat expansion

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are the main syndromes of the chromosome 9 ORF72 (C9ORF72) hexanucleotide repeat expansion, but studies have shown a substantial phenotypic diversity that includes psychiatric presentations. This study describes hippocampal sclerosis dementia (HSD) in carriers of the C9ORF72 mutation. We compared clinical and neuropathological features of HSD in carriers and noncarriers autopsied at Johns Hopkins. Carriers presented with amnesia, agitation, dissocial behavior, and impaired self-care, whereas noncarriers showed little agitation. The groups were not dissimilar in cognitive or motor dysfunction. Neuropathological examination of carriers showed cerebellar neuronal inclusions positive for ubiquitin, p62, and ubiquilin-2, and negative for TAR DNA-binding protein 43. Noncarriers did not have cerebellar inclusions. C9ORF72 repeat-associated non-ATG translation was confirmed by immunohistochemistry. These observations broaden the C9ORF72 phenotype and place HSD in the FTD spectrum. The amnesic phenotype of HSD, which is consistent with the focal hippocampal atrophy, should be included in clinical categorizations of FTD.

Hippocampal and mesial temporal sclerosis in early-onset frontotemporal lobar degeneration versus Alzheimer's disease

Hippocampal sclerosis (HS) and mesial temporal sclerosis (MTS) may occur with frontotemporal lobar degeneration (FTLD) and Alzheimer's disease (AD) as well as with normal aging. Prior studies suggest that HS/MTS may be more closely associated with FTLD but have not directly compared the prevalence and clinical characteristics of HS/MTS between neuropathologically confirmed early-onset (age ≤ 65) cohorts of FTLD and AD. We identified patients with early-onset FTLD (n = 136) and AD (n = 267) from National Alzheimer's Center Consortium databases and compared neuropathological and clinical data between these 2 groups. The FTLD group had a significantly higher prevalence of HS/MTS than that of the AD group. However, HS/MTS was associated with increasing age and memory impairment in the AD group but not in the FTLD group. These findings are consistent with the hypothesis that HS/MTS in FTLD occurs as part of the primary pathological process, rather than as a secondary, nonspecific effect of aging on memory and hippocampal function.

Hippocampal sclerosis of aging, a prevalent and high-morbidity brain disease

Hippocampal sclerosis of aging (HS-Aging) is a causative factor in a large proportion of elderly dementia cases. The current definition of HS-Aging rests on pathologic criteria: neuronal loss and gliosis in the hippocampal formation that is out of proportion to AD-type pathology. HS-Aging is also strongly associated with TDP-43 pathology. HS-Aging pathology appears to be most prevalent in the oldest-old: autopsy series indicate that 5-30 % of nonagenarians have HS-Aging pathology. Among prior studies, differences in study design have contributed to the study-to-study variability in reported disease prevalence. The presence of HS-Aging pathology correlates with significant cognitive impairment which is often misdiagnosed as AD clinically. The antemortem diagnosis is further confounded by other diseases linked to hippocampal atrophy including frontotemporal lobar degeneration and cerebrovascular pathologies. Recent advances characterizing the neurocognitive profile of HS-Aging patients have begun to provide clues that may help identify living individuals with HS-Aging pathology. Structural brain imaging studies of research subjects followed to autopsy reveal hippocampal atrophy that is substantially greater in people with eventual HS-Aging pathology, compared to those with AD pathology alone. Data are presented from individuals who were followed with neurocognitive and neuroradiologic measurements, followed by neuropathologic evaluation at the University of Kentucky. Finally, we discuss factors that are hypothesized to cause or modify the disease. We conclude that the published literature on HS-Aging provides strong evidence of an important and under-appreciated brain disease of aging. Unfortunately, there is no therapy or preventive strategy currently available.

Hippocampal sclerosis dementia: An amnesic variant of frontotemporal degeneration

OBJECTIVE

To describe characteristics of hippocampal sclerosis dementia.

METHODS

Convenience sample of Hippocampal sclerosis dementia (HSD) recruited from the Johns Hopkins University Brain Resource Center. Twenty-four cases with post-mortem pathological diagnosis of hippocampal sclerosis dementia were reviewed for clinical characterization.

RESULTS

The cases showed atrophy and neuronal loss localized to the hippocampus, amygdala and entorrhinal cortex. The majority (79.2%) had amnesia at illness onset, and many (54.2%) showed abnormal conduct and psychiatric disorder. Nearly 42% presented with an amnesic state, and 37.5% presented with amnesia plus abnormal conduct and psychiatric disorder. All eventually developed a behavioral or psychiatric disorder. Disorientation, executive dysfunction, aphasia, agnosia and apraxia were uncommon at onset. Alzheimer disease (AD) was the initial clinical diagnosis in 89% and the final clinical diagnosis in 75%. Diagnosis of frontotemporal dementia (FTD) was uncommon (seen in 8%).

CONCLUSION

HSD shows pathological characteristics of FTD and clinical features that mimic AD and overlap with FTD. The findings, placed in the context of earlier work, support the proposition that HSD belongs to the FTD family, where it may be identified as an amnesic variant.

Prevalence, laterality, and comorbidity of hippocampal sclerosis in an autopsy sample

Hippocampal sclerosis (HS) is a common and often asymmetric neuropathological finding among elderly persons who experience progressive memory loss, but its cause is unknown and it is rarely diagnosed during life. In order to improve both understanding and diagnosis of late-life HS, bilateral hippocampi and cerebral hemispheres were reviewed in 130 consecutive autopsy cases drawn from a longitudinal study of subjects with subcortical ischemic vascular dementia (IVD), Alzheimer disease (AD) and normal aging. HS was found in 31 of 130 cases (24.5%). Of these, 45% were bilateral, 32% left-sided, and 23% right-sided. The majority of HS cases involved the entire rostral-caudal extent of the hippocampus. However, in 7 cases HS was focal in nature and was only found at or anterior to the lateral geniculate nucleus. In 77% of cases, HS was accompanied by other types of pathology ('mixed' HS), but in 23% of cases it was the sole neuropathologic finding ('pure' HS). TDP-43-positive cytoplasmic inclusions were found in dentate granule cells in 93% of all HS cases, 55% of AD cases with no HS, but 0% of IVD cases with no HS. MRI hippocampal volumes were significantly lower in bilateral HS compared to AD (p < 0.001) and in unilateral HS cases compared to cases with intact hippocampi (p < 0.001). Since HS may occur unilaterally in approximately a quarter of cases, its prevalence may be underestimated if only one cerebral hemisphere is examined. The presence of TDP-43 inclusions in HS cases, regardless of accompanying pathologies (e.g., AD, IVD, FTLD), is consistent with an underlying neurodegenerative pathogenetic mechanism. Further studies are warranted to determine whether greater severity of hippocampal atrophy on MRI may assist the clinical differentiation of HS from AD.

Hippocampal sclerosis in advanced age: clinical and pathological features

Hippocampal sclerosis is a relatively common neuropathological finding (∼10% of individuals over the age of 85 years) characterized by cell loss and gliosis in the hippocampus that is not explained by Alzheimer's disease. Hippocampal sclerosis pathology can be associated with different underlying causes, and we refer to hippocampal sclerosis in the aged brain as hippocampal sclerosis associated with ageing. Much remains unknown about hippocampal sclerosis associated with ageing. We combined three different large autopsy cohorts: University of Kentucky Alzheimer's Disease Centre, the Nun Study and the Georgia Centenarian Study to obtain a pool of 1110 patients, all of whom were evaluated neuropathologically at the University of Kentucky. We focused on the subset of cases with neuropathology-confirmed hippocampal sclerosis (n=106). For individuals aged≥95 years at death (n=179 in our sample), each year of life beyond the age of 95 years correlated with increased prevalence of hippocampal sclerosis pathology and decreased prevalence of 'definite' Alzheimer's disease pathology. Aberrant TAR DNA protein 43 immunohistochemistry was seen in 89.9% of hippocampal sclerosis positive patients compared with 9.7% of hippocampal sclerosis negative patients. TAR DNA protein 43 immunohistochemistry can be used to demonstrate that the disease is usually bilateral even when hippocampal sclerosis pathology is not obvious by haematoxylin and eosin stains. TAR DNA protein 43 immunohistochemistry was negative on brain sections from younger individuals (n=10) after hippocampectomy due to seizures, who had pathologically confirmed hippocampal sclerosis. There was no association between cases with hippocampal sclerosis associated with ageing and apolipoprotein E genotype. Age of death and clinical features of hippocampal sclerosis associated with ageing (with or without aberrant TAR DNA protein 43) were distinct from previously published cases of frontotemporal lobar degeneration TAR DNA protein 43. To help sharpen our ability to discriminate patients with hippocampal sclerosis associated with ageing clinically, the longitudinal cognitive profile of 43 patients with hippocampal sclerosis associated with ageing was compared with the profiles of 75 controls matched for age, gender, education level and apolipoprotein E genotype. These individuals were followed from intake assessment, with 8.2 (average) longitudinal cognitive assessments. A neuropsychological profile with relatively high-verbal fluency but low word list recall distinguished the hippocampal sclerosis associated with ageing group at intake (P<0.015) and also 5.5-6.5 years before death (P<0.005). This may provide a first step in clinical differentiation of hippocampal sclerosis associated with ageing versus pure Alzheimer's disease in their earliest stages. In summary, in the largest series of autopsy-verified patients with hippocampal sclerosis to date, we characterized the clinical and pathological features associated with hippocampal sclerosis associated with ageing.

Common variant in GRN is a genetic risk factor for hippocampal sclerosis in the elderly

BACKGROUND

Hippocampal sclerosis (HpScl) is common in elderly subjects with dementia, either alone or accompanied by other pathologic processes. It is also found in >70% of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions (FTLD-TDP). TDP-43 inclusions are detected in >20% of Alzheimer disease (AD) and >70% of HpScl cases. The most common cause of FTLD-TDP is mutation in the progranulin gene (GRN). Recently, a common genetic variant in the 3' untranslated region (3'UTR) of GRN (rs5848; c.*78C>T) located in a microRNA binding site regulated progranulin expression, and the T-allele was increased in FTLD-TDP compared to controls.

OBJECTIVE

The goal of this study was to determine if the 3'UTR variant in GRN was associated with TDP-43 immunoreactivity in AD with and without HpScl.

METHODS

644 cases of pathologically confirmed AD, including 57 with HpScl, were screened for TDP-43 immunoreactivity and were genotyped at the GRN 3'UTR single-nucleotide polymorphism rs5848 using previously published methods.

RESULTS

There was a trend (p = 0.06) for TDP-43 immunoreactivity, but a very significant (p = 0.005) association of HpScl with the variant, with 72% of AD with HpScl carrying a T-allele, compared to 51% of AD without HpScl carrying a T-allele.

CONCLUSION

The results suggest that a genetic variant in GRN leading to decreased levels of progranulin may be a risk factor for HpScl in AD, while its role in TDP-43 immunoreactivity in AD remains less certain.

Depression in frontotemporal dementia

OBJECTIVE

The authors describe mood abnormalities seen in a case series of patients with frontotemporal dementia (FTD).

METHOD

Authors provide a structured review of outpatient and inpatient charts of FTD patients.

RESULTS

Three distinct depressive syndromes were identified: The first corresponds to DSM-IV major depression. The second is a syndrome of mood lability with prominent responsiveness to the environment. The third is a syndrome of profound apathy, without other evidence of depression.

CONCLUSION

A variety of mood disorders are seen in FTD, requiring careful attention to differential diagnosis. FTD should be included in the differential diagnosis during the evaluation of older patients with mood abnormalities.

Hippocampal sclerosis with four-repeat tau-positive round inclusions in the dentate gyrus: a new type of four-repeat tauopathy

Hippocampal sclerosis is defined as selective neuronal loss and gliosis of the hippocampus with heterogeneous etiologies, including neurodegenerative tauopathies. We report a 78-year-old woman who presented with depression, in whom postmortem examination revealed almost complete loss of neurons with gliosis in the subiculum and CA1-3 regions of the hippocampus and abundant neuronal cytoplasmic inclusions in the dentate gyrus. The inclusions were round, slightly basophilic and argyrophilic, resembling Pick bodies. However, they were Gallyas- and 4-repeat tau-positive, and 3-repeat tau- and ubiquitin-negative. To our knowledge, the histopathological features in this case were different from those in hippocampal sclerosis or 4-repeat tauopathies reported previously. It is likely that this case is a new variant of 4-repeat tauopathy presenting with hippocampal sclerosis.

Recurrent seizures in patients with dementia: frequency, seizure types, and treatment outcome

OBJECTIVE

Patients with a primary neurodegenerative disorder associated with cognitive impairment are at increased risk for epilepsy. The goal of the present study was to characterize seizure type(s), etiological diagnosis of dementia, electroencephalogram (EEG) and imaging findings, and response to antiepileptic drug (AED) therapy in these individuals.

METHODS

A retrospective study was performed identifying patients in the Mayo Alzheimer Disease Patient Registry (ADPR) and Alzheimer Disease Research Center (ADRC) who were classified as having dementia and epilepsy from 1986 to 2006. Multiple clinical parameters were extracted from patient charts and evaluated to characterize the primary neurodegenerative disorder and seizure outcomes.

RESULTS

Sixty-three of the 1738 ADPR and ADRC patients (3.6%) had epilepsy. Twenty-four of the 63 patients were excluded because of insufficient information regarding their epilepsy. The remaining 39 patients were analyzed. Twenty-eight of the 63 patients (72%) experienced complex partial seizures. Head MRI was performed in 35 patients (90%). Fourteen patients (36%) had MRI-identified structural lesions that included remote stroke and prior intracerebral hemorrhage. EEGs were obtained in 29 patients (74%). Fifteen patients (38%) had epileptiform discharges. Overall, it was found that 79% had an excellent response to AED therapy. Approximately one-third of the patients had dose-related side effects from an AED.

CONCLUSION

The present study indicated that most individuals with the comorbidity of epilepsy and dementia have complex partial seizures that may be adequately controlled on AED therapy. The long-term effect of seizure activity on the neurodegenerative disorder is unknown.

Understanding hippocampal sclerosis in the elderly: epidemiology, characterization, and diagnostic issues

Hippocampal sclerosis (HS) is a pathologic term used to describe severe loss of neurons and reactive gliosis without cystic cavitation in the CA1 sector of the hippocampus. In late life, HS is associated with hippocampal atrophy, severe amnesia, and slowly progressive dementia without clinical seizure activity. HS is difficult to distinguish clinically from Alzheimer's disease and is often diagnosed postmortem. In autopsy series, HS may be found without significant other pathology (2%-4% of cases), but it occurs frequently in combination with other vascular and neurodegenerative disorders (12%-20% of cases). HS is found bilaterally in 50% of cases and unilaterally in 50% of cases, with similar predilection for the right versus left hemisphere. The pathogenesis of HS is unknown and may be multifactorial in origin, possibly due to anoxic/ischemic injury or TDP-43-related neurodegeneration. Little is known about the prevention and treatment of late-life HS, although circumstantial evidence suggests the importance of identifying and treating vascular risk factors.

TAR DNA-binding protein 43 immunohistochemistry reveals extensive neuritic pathology in FTLD-U: a midwest-southwest consortium for FTLD study

TAR DNA-binding protein 43 (TDP-43) is a major component of the inclusions in frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U). We studied TDP-43 pathology in the hippocampus and frontal cortex of autopsy brains from patients with FTLD-U (n = 68), dementia lacking distinctive histopathology (n = 4), other neurodegenerative diseases (n = 23), and controls (n = 12) using a sensitive immunohistochemistry protocol. Marked enhancement of staining of TDP-43-positive dystrophic neurites (DNs) was obtained, and we observed 2 previously unrecognized pathologic patterns (i.e. frequent long DNs in the CA1 region and frequent dot-like DNs in the neocortical layer 2) in 39% and 15% of the FTLD-U cases, respectively. Frequent long DNs, but not dot-like DNs, were significantly associated with progranulin mutations. Based on this evaluation, 4 FTLD-U cases showed no TDP-43 pathology and were reclassified as "FTLD-U, non-TDP-43 proteinopathy," and 3 cases of dementia lacking distinctive histopathology were reclassified as FTLD-U. Of the cases with other neurodegenerative diseases, 43% showed TDP-43 pathology in the hippocampus, but only 4% showed TDP-43 pathology in the frontal cortex. No TDP-43 pathology was seen in controls. These results indicate that the sensitivity of the TDP-43 immunohistochemistry method affects both the extent and type of abnormalities detected. Moreover, assessment of abnormalities in both the hippocampus and frontal cortex may be diagnostically important in FTLD-U.

Late-onset temporal lobe epilepsy with unilateral mesial temporal sclerosis and cognitive decline: a diagnostic dilemma

We present a patient with new onset temporal lobe epilepsy and cognitive decline in his sixth decade with unilateral hippocampal atrophy on structural brain imaging, compatible with mesial temporal sclerosis. This unusual clinical scenario presented a challenging differential diagnosis since it may overlap with primary cognitive disorders, including early-onset Alzheimer's disease and some forms of frontotemporal dementia, and the recently elucidated syndrome of non-paraneoplastic limbic encephalitis associated with voltage-gated potassium channel antibodies.

Frontotemporal lobar degeneration with motor neurone disease (FTLD/MND): Presentations in psychiatric practice

Background. Concurrence of frontotemporal lobar degeneration with clinical features of motor neurone disease (FTLD/MND) is a recognised cause of dementia with widely accepted diagnostic criteria, but it is not mentioned in DSM-IV-TR. Aim. To draw attention to cases of FTLD/MND referred by psychiatrists, or already under the care of psychiatrists at time of referral, to a dedicated Cognitive Function Clinic. Methods. Prospective study of FTLD/MND cases, 1999-2007 inclusive; case note review. Results. Nine of 13 cases of FTLD/MND were either referred by or already under the care of a psychiatrist. Although most had been identified as having a dementia, in none had the correct diagnosis been made. All patients had signs of motor neurone pathology on clinical examination, sometimes subtle, in addition to cognitive and psychiatric features. A wide variety of drugs had been prescribed including antidepressants, antipsychotics, cholinesterase inhibitors, and memantine. Conclusions. A high index of clinical suspicion is required to identify cases of possible FTLD/MND, and thereby initiate appropriate investigations and management and avoid inappropriate medication. Absence of FTLD/MND in DSM-IV-TR may further handicap psychiatrists in making this diagnosis.

Hippocampal sclerosis dementia: a reappraisal

Hippocampal sclerosis (HpScl) is characterized by neuronal loss and gliosis in CA1 and subiculum of the hippocampus, and may be one contributing factor to dementia in old age. The term hippocampal sclerosis dementia (HpSclD) designates the presence of both hippocampal sclerotic lesions and a dementia syndrome. In the present review, we outline the pathological heterogeneity underlying HpSclD and discuss related disorders due to tau protein pathology and frontotemporal dementia with ubiquitin positive inclusions (FTLD-U). We also provide a detailed morphological description of ten of our own autopsied HpSclD cases, and compare these pathological findings with those reported in the literature. The lateralization of HpScl and the atrophy of the mammillary bodies were striking features in most of our cases. The main pathology consisted of tau positive lesions with a predominance of neuronal and glial pretangles in Ammon's horn and the dentate gyrus. Neurofibrillary and ghost tangles in CA1 and the subiculum were scarce and thus insufficient to explain the hippocampal pyramidal cell loss. In some cases, tau pathology in the hippocampal formation coexisted with glial tau pathology in the frontal cortex. The most striking finding besides the tau pathology was the presence of concomitant neuronal cytoplasmic inclusions and neurites immunoreactive for the transactive response DNA-binding protein-43 (TDP-43) in the dentate gyrus and temporal neocortex, similar to those found in FTLD-U. Taken together, the pathology of HpSclD is indicative of a degenerative rather than a hypoxic/ischemic etiology of HpSclD. Presently, HpSclD may best be deemed a disorder with various neurodegenerative etiologies, most notably tauopathy and TDP-43 proteinopathy (i.e. FTLD-U). Each of these disease processes could either independently or concertedly account for the dementia syndrome in HpSclD.

Neuropsychological deficits in frontotemporal dementia and Alzheimer's disease: a meta-analytic review

We sought to identify the cognitive tests that best discriminate between Alzheimer's disease (AD) and frontotemporal dementia (FTD). A comprehensive search of all studies examining the cognitive performance of persons diagnosed with AD and FTD, published between 1980 and 2006, was conducted. Ninety-four studies were identified, comprising 2936 AD participants and 1748 FTD participants. Weighted Cohen's d effect sizes, percentage overlap statistics, confidence intervals and fail-safe Ns were calculated for each cognitive test that was used by two or more studies. The most discriminating cognitive tests were measures of orientation, memory, language, visuomotor function and general cognitive ability. Although there were large and significant differences between groups on these measures, there was substantial overlap in the scores of the AD and FTD groups. Age, education, years since diagnosis and diagnostic criteria did not significantly contribute to the group differences. Given the large overlap in the test performance of persons diagnosed with AD and FTD, cognitive tests should be used cautiously and in conjunction with a medical history, behavioural observations, imaging and information from relatives when making differential diagnoses.

Contribution of depression to cognitive impairment and dementia in older adults

BACKGROUND

The objective of this review is to provide information for clinicians regarding current research and opinions on the association of depression to conditions of cognitive impairment and dementia. We also intend to integrate this current research and thinking into strategies for the assessment and treatment of depression in the context of cognitive impairment.

REVIEW SUMMARY

Depression is highly prevalent in mild cognitive impairment and most dementias. It may be a risk factor for the subsequent development of dementia and in some conditions may be a prodromal symptom. It is important to detect and effectively treat depression because the comorbidity of depression and cognitive impairment is associated with greater cognitive and functional decline and higher rates of institutionalization. Depression often can be differentiated from Alzheimer disease and other dementias based on characteristics of clinical history and presentation. Screening of depression and cognitive impairment will help characterize the presence and severity of these conditions, but limitations in screening approaches may necessitate comprehensive assessment in complex cases where differential diagnosis is important to treatment planning.

CONCLUSION

Although depression and cognitive impairment are important issues in the treatment of older adults, there are particular risks when they occur together. Appropriate assessment and screening can help guide the clinician to appropriate and timely interventions. Pharmacologic and nonpharmacologic treatment approaches are both efficacious in reducing depression in cognitive impairment and dementia.

Biochemical and pathological characterization of frontotemporal dementia due to a Leu266Val mutation in microtubule-associated protein tau in an African American individual

Frontotemporal dementia (FTD) is a clinically heterogeneous disorder characterized by alterations in language and/or behavior, often in association with Parkinsonism or motor neuron disease. A familial form of FTD is associated with mutations in the microtubule-associated protein tau (MAPT) gene. We report here on the clinical, neuroimaging, cerebral spinal fluid biomarker, genetic, biochemical and postmortem neuropathological analyses of a case of familial FTD with a Leu266Val MAPT mutation which results in a very early age of onset and a rapid course of disease. This is also the first reported case of any MAPT mutation in an individual of African American ethnicity.

MRI evidence of bilateral hippocampal sclerosis in amnestic mild cognitive impairment

We present the case of a man affected by amnestic mild cognitive impairment (aMCI) who showed bilateral hippocampal sclerosis at magnetic resonance imaging (MRI). We argue the concept that aMCI is heterogeneous syndrome and suggested the utility of coronal T2-weighted MRI images in the routine dementia workup.

Hippocampal sclerosis in tau-negative frontotemporal lobar degeneration

Tau-negative frontotemporal lobar degeneration (FTLD) can be divided into those with motor neuron disease (FTLD-MND), and those without MND, but with ubiquitin-immunoreactive neuronal inclusions (FTLD-U). Some authors group FTLD-U and FTLD-MND together as tau-negative FTLD, but others separate them on the basis of clinical, pathologic and imaging differences. In 103 cases of pathologically confirmed, tau-negative FTLD (FTLD-MND and FTLD-U), we assessed the frequency of hippocampal sclerosis defined as neuronal loss in the subicular or CA1 regions of the hippocampus. The subjects in the FTLD-U group were older at death and had longer disease duration. After adjusting for age at death and disease duration, we found a significant difference in the frequency of hippocampal sclerosis in the FTLD-U group (79%) compared to FTLD-MND group (26%) (p=0.02). The difference in frequency of HpScl in FTLD-U compared to FTLD-MND is further evidence that they are separate clinicopathologic entities.

National Institute of Neurological Disorders and Stroke-Canadian Stroke Network vascular cognitive impairment harmonization standards

BACKGROUND AND PURPOSE

One in 3 individuals will experience a stroke, dementia or both. Moreover, twice as many individuals will have cognitive impairment short of dementia as either stroke or dementia. The commonly used stroke scales do not measure cognition, while dementia criteria focus on the late stages of cognitive impairment, and are heavily biased toward the diagnosis of Alzheimer disease. No commonly agreed standards exist for identifying and describing individuals with cognitive impairment, particularly in the early stages, and especially with cognitive impairment related to vascular factors, or vascular cognitive impairment.

METHODS

The National Institute for Neurological Disorders and Stroke (NINDS) and the Canadian Stroke Network (CSN) convened researchers in clinical diagnosis, epidemiology, neuropsychology, brain imaging, neuropathology, experimental models, biomarkers, genetics, and clinical trials to recommend minimum, common, clinical and research standards for the description and study of vascular cognitive impairment.

RESULTS

The results of these discussions are reported herein.

CONCLUSIONS

The development of common standards represents a first step in a process of use, validation and refinement. Using the same standards will help identify individuals in the early stages of cognitive impairment, will make studies comparable, and by integrating knowledge, will accelerate the pace of progress.

Telling the difference between frontotemporal dementia and Alzheimer's disease

PURPOSE OF REVIEW

A precise diagnosis of the cause of dementia during life is needed for proper management, in order to explain the symptoms to the patient and to the close relatives, and to give appropriate indications on the prognosis and possibly on the genetic risk. Frontotemporal dementia remains under-diagnosed and often misdiagnosed for Alzheimer's disease, the most common cause of dementia. More and more studies explore the differences between the two syndromes.

RECENT FINDINGS

Progress in neuropsychological testing improves the ability to distinguish between syndromes and knowledge on brain functioning. More attention has been paid over these last months--or years--on emotion, insight, behavior, artistic creativity and quality of responses. Yet, biomarkers do not improve the diagnostic accuracy of trained clinicians, and do not help to distinguish between histological subtypes of frontotemporal dementia.

SUMMARY

Improvement in knowledge on cognitive and emotional impairment in frontotemporal dementia and Alzheimer's disease is essential for the management of the patient--information can be given to the patients and the families that helps them to understand and to behave in consequence.

Hyperorality in Epileptic Seizures: Periictal Incomplete Kluver-Bucy Syndrome

PURPOSE

To analyze systematically hyperorality associated with epileptic seizures and its relation to the localization of epileptic activity.

METHODS

To identify patients with periictal hyperorality, we reviewed video-recordings of 269 patients (aged 6-59 years) who had consecutively undergone presurgical evaluations including ictal video-EEG recordings and high-resolution magnetic resonance imaging (MRI) and had had epilepsy surgery because of intractable frontal (FLE) or temporal lobe epilepsy (TLE). Periictal hyperorality was defined if patients put or unambiguously intended to put nonfood items into their mouths during or after at least one of the reviewed seizures. For the further analysis, we included only patients with periictal hyperorality. We reviewed their medical records and reexamined their ictal video-EEG recordings.

RESULTS

We identified eight patients (six women) aged 8-59 years who had hyperorality during or after seizures. Seven patients had TLE, and one patient had frontal lobe epilepsy (FLE). Three of these patients underwent right-sided surgery, whereas five patients had surgery on the left. Three patients exhibited ictal and five showed postictal hyperorality. Interictal EEG suggested bilateral interictal epileptiform discharges (IEDs) in three patients; in two other patients, no IEDs were detected. Ictal EEG suggested bilateral involvement in six cases. Patients with unilateral epileptiform activity had left TLE.

CONCLUSIONS

Periictal hyperorality is a rare phenomenon occurring in 3% of the investigated epilepsy population. We suggest that periictal hyperorality is an ictal-postictal mental disturbance, an incomplete Klüver-Bucy syndrome. In most patients, bilateral seizure activity plays an important role in the pathomechanism, but it would appear that left-sided epileptic activity without contralateral involvement also can cause periictal hyperorality.

Quantitative post-mortem study of the hippocampus in chronic epilepsy: seizures do not inevitably cause neuronal loss

Hippocampal sclerosis describes a pattern of neuronal loss and gliosis involving the medial temporal structures most often encountered in patients with epilepsy. It is still a matter for debate as to whether this lesion is acquired during the course of the patient's seizure history or is present at the outset. Early febrile seizures, episodes of status epilepticus as well as repetitive brief seizures may all contribute to the evolution of hippocampal sclerosis. In addition, genetic factors and developmental abnormalities of the hippocampus may both increase vulnerability to seizures and hippocampal injury. Recent human studies have addressed neuropathological changes in young adults and children undergoing surgery for refractory seizures with hippocampal sclerosis. Post-mortem examination, however, provides the opportunity to evaluate the effect of a lifetime of seizures on both left and right hippocampi, and the presence of any co-existing malformation. Post-mortem stereological analysis of 28 patients with poorly controlled seizures has confirmed a subgroup with absence of significant hippocampal neuronal loss despite decades of generalized seizures, including status epilepticus. The presence of granule cell dispersion correlated to the severity of hippocampal neuronal loss. Furthermore, in patients with confirmed hippocampal sclerosis at post-mortem examination, stereological assessment of the neocortex failed to confirm significant white matter neuronal heterotopia that might indicate an underlying developmental abnormality. In conclusion, seizures do not invariably lead to hippocampal injury and white matter heterotopia is not invariably associated with hippocampal sclerosis.