Identification of subgroups in amnestic mild cognitive impairment

The DMS48 is a visual recognition memory test designed to detect memory changes in early Alzheimer disease (AD). Patients with amnestic mild cognitive impairment (aMCI) who succeeded on this task exhibited frontal hypoperfusion on SPECT. In contrast, failure was associated with temporomesial and temporoparietal hypoperfusion, a pattern usually described in the early stages of AD. It may possible to detect patients at high risk for AD within a population of aMCI.

The right temporal lobe variant of frontotemporal dementia

The right temporal variant of frontotemporal lobar degeneration (Rtv-FTLD) is a focal degenerative condition affecting predominantly the right temporal lobe. The aim of this study was to further characterize the profile of cognitive impairment and the neuroanatomical basis of Rtv-FTLD patients without behavioural disturbances. A group of three patients with this syndrome had a detailed neuropsychological assessment, along with Voxel-Based Morphometry (VBM) of their brain to determine location of cortical atrophy. VBM analyses showed a pattern of atrophy that was predominant in the right hemisphere and concerned primarily the right anterior temporal lobe region. Patients carried out a test of famous people in which their ability to recognize, name and provide semantic information about famous persons from their faces, their voices and their names was investigated. They all showed a severe defect in recognizing, naming and identifying famous people irrespective of modality. Therefore, their inability to recognize famous people resulted from a multimodal defect (semantic). These results highlight the semantic nature of the defect, and suggest that the anterior right temporal lobe may have a prominent role in processing person-based semantic knowledge. This study helps in further understanding the neuropsychological profile of patients with Rtv-FTLD.

[The human perirhinal cortex]

The perirhinal cortex is a structure that lies within the medial temporal lobe. In the present paper, we review current knowledge of the anatomical boundaries and functional correlates of this structure. In the past decade, numerous animal studies have attempted to understand the contribution of the perirhinal cortex to memory. Taken together, they suggest that the perirhinal cortex is crucially involved in recognition memory. This function appears to be independent from those assumed to be subserved by the hippocampus. In humans, data are scarce but tend to corroborate results found in the animal literature. The perirhinal cortex appears to support context-free (non-episodic) knowledge, such as general knowledge about the world and "item-specific" memories. Models of declarative memory that take into account the specific contribution of the perirhinal cortex are discussed, along with their potential application to early cortical neurodegenerative disorders.

Evaluation of visual recognition memory in MCI patients

BACKGROUND

Neurofibrillary tangles seen early in Alzheimer disease (AD) initially appear in a subregion of the perirhinal cortex. In the monkey, damage to the perirhinal cortex impairs performance on visual recognition memory tasks. The authors evaluated impairment of visual recognition memory as a potential early diagnostic marker of AD.

METHODS

The authors developed a visual delayed matching-to-sample task (DMS48) designed to assess visual recognition memory in humans. Twenty-three patients fulfilling the criteria of amnestic mild cognitive impairment (MCI) (mean Mini-Mental State Examination [MMSE]: 26.6, SD = 1.6) were recruited. All underwent a full neuropsychological evaluation, which included the Free and Cued Selective Reminding (FCSR) test. Their performance was compared with that of 10 patients with mild AD, 20 patients with moderate AD, 20 patients with Parkinson disease (PD), and 40 age-matched controls.

RESULTS

Control subjects and patients with PD performed close to ceiling. Patients with mild AD had very low scores, while patients with moderate AD answered at random. MCI patients obtained scores that were between those of control subjects and patients with mild AD (78%, SD = 16%). MCI patients who failed on the DMS48 had lower scores on free recall (p < 0.05) and received less benefit from cueing (p < 0.01) on the FCSR than the other MCI, suggesting a profile of genuine memory impairment related to medial temporal lobe lesions.

CONCLUSION

The DMS48, a test of visual recognition memory, is impaired early in the course of patients with MCI. Further studies are necessary to determine whether the evaluation of visual recognition memory may contribute to the identification of patients with AD.

Pointing to body parts: a double dissociation study

Since Pick's seminal studies on autotopagnosia dating back to the beginning of last century, no agreement has been reached regarding the nature of the putative representations underlying the act of pointing to body parts. One influential account proposed the existence of a meta-representation, eventually organised as a module, specifically engaged in encoding spatial relationships of bodies. This body-specific representational level has been supposed to be equally involved in processing other persons' bodies as well as one's own. Here, we report two patients with dissociated performances in pointing to human body parts, thereby providing an interesting opportunity to discuss current models of body organisation. JR exhibited a selective deficit in pointing to his own body parts and a preserved ability to point to the parts of others. In contrast, AP demonstrated a selective inability to point to another person's body parts while her capacity to point to her own was intact. To further evaluate the level of body-specificity of AP's impairment, she underwent additional pointing tasks using non-human and human representations. AP's performances were close to those of control subjects across experiments, supporting the idea that processing the spatial layout of another person's body relies on a specific representational and neural system. Based on available data in the literature and the putative areas of lesion evidenced by cerebral blood flow studies in our two subjects, we hypothesise that left superior and inferior parietal regions are parts of networks involved in the respective processing of somatosensory and visuospatial representations of bodies.

Apolipoprotein E gene in frontotemporal dementia: an association study and meta-analysis

No definite genetic risk factor of non-monogenic frontotemporal dementia (FTD) has yet been identified. Several groups have examined the potential association of FTD with the apolipoprotein E (APOE) gene, but the results are inconsistent. Our objective was to determine whether APOE is a risk factor of FTD, using the largest series of patients with FTD and controls analysed so far (94 unrelated patients and 392 age and sex-matched controls), and a meta-analysis. Homozygosity for the E2E2 genotype was significantly associated with FTD (odds ratio (OR)=11.3; P=0.033, exact test). After stratification on familial history (FH) for FTD, the OR for E2E2 was still found significant when analysing only patients with a positive FH (OR=23.8; P=0.019). The meta-analysis, using 10 case-control studies with available genotype or allele information, comprising a total of 364 FTD patients and 2671 controls, including the patients of the present study, did not reach statistical significance even if the E2E2 genotype was more frequent in patients than in controls (0.018 vs 0.006, respectively). Because of studies heterogeneity (Mantel-Haenszel statistics: P=0.004), we analysed on one hand the neuropathologically-confirmed studies, and on the other hand the clinical-based studies. In the neuropathologically-confirmed studies (Mantel-Haenszel statistics: P=ns), we found a significant increase of the E2 allele frequency in FTD patients (OR[E2 vs E3]=2.01; 95% CI=1.02-3.98; P=0.04). The same result was found in the clinical-based studies, but studies heterogeneity remained. No result was significant with the E4 allele. The E2 allele seems so to be a risk factor of FTD whereas this allele is associated with the lowest risk in Alzheimer's disease. If this finding was confirmed, it could provide new insights into the mechanisms of differential risk related to APOE in neurodegenerative diseases.

Association between the extended tau haplotype and frontotemporal dementia

BACKGROUND

Recent studies have shown an association between an extended tau haplotype (H1) that covers the entire human tau gene and progressive supranuclear palsy or, more inconsistently, other neurodegenerative disorders, such as corticobasal degeneration, Parkinson disease, Alzheimer disease, and frontotemporal dementia (FTD). In addition, disease-causing mutations in the tau gene on chromosome 17 have been detected in some families with autosomal dominant FTD and parkinsonism. In FTD, the pathological accumulation of the microtubule-associated protein tau suggests that the tau gene may be a genetic risk factor for this disorder.

OBJECTIVE

To confirm or refute the association between the H1 haplotype or the H1H1 genotype of the tau gene and FTD.

DESIGN

Case-control study.

SETTING

Neurology departments of 12 French university hospitals.

PARTICIPANTS

One hundred unrelated patients with FTD and 79 controls.

METHODS

Tau genotype (contiguous polymorphisms in exons 1, 7, and 13 and in intron 9 used to reconstruct the extended haplotypes H1 and H2). Clinical examination, psychometric testing, laboratory tests, computed tomography and magnetic resonance imaging, single-photon emission computed tomography, and electroencephalography for patients with FTD.

RESULTS

The H1H1 genotype was significantly overrepresented in patients with FTD compared with controls (62% vs 46%; P=.01, 1-sided; odds ratio adjusted for age and sex, 1.95). After stratification according to apolipoprotein E (APOE) genotype, we found a significant interaction between APOE and tau genotypes (P=.03).

CONCLUSIONS

This study of the largest series of patients with FTD confirms the primary role of tau in FTD and establishes that the H1 haplotype of the tau gene and the E2 allele of APOE interact by an unknown mechanism that increases the risk of FTD.

Progressive loss of speech: a neuropsychological profile of premotor dysfunction

Several patients with 'progressive loss of speech output' or 'progressive anarthria' of degenerative origin have been reported in the literature. We report 5 clinical cases with slowly progressive loss of speech output and initially no deficit in other cognitive domains. The early clinical features were analysed in an attempt to identify the anatomo-functional systems implied in the degenerative process. The first phase of the disorder was characterised by impaired articulation consistent with speech apraxia, telegraphic style and a difficulty to elaborate a series of orofacial or hand movements. It is argued that these symptoms result from an impairment of complex motor processing due to dysfunction of the ventral premotor system. In the second phase, a decrease in spontaneous speech and self-initiated action was combined with exaggerated dependency on external stimuli, interpreted as dysfunction of the dorsal premotor system. We suggest that the neuropsychological profile of the disorder may result from progressive degeneration of the premotor cortex.

[Progressive focal cortical atrophies]

Progressive focal cortical atrophies are degenerative conditions characterised by the insidious onset and gradual exacerbation of an impairment in a single cognitive domain related to circumscribed cerebral atrophy. Several focal cortical syndromes with deficits in the realm of cognition are reviewed: progressive impairment of language (primary progressive aphasia), speech (progressive anarthria), semantic memory (semantic dementia), episodic memory (pure progressive amnesia), vision (progressive perceptual or visuo-spatial deficits) and gesture (progressive apraxia). These conditions are histologically heterogeneous and can be associated with focal non-specific neuronal loss and gliosis with some spongiform changes (non-specific lesions), pathological features of Pick's disease (inclusion bodies and swollen neurones) or Alzheimer's disease (AD) (senile plaques and neurofibrillary tangles). A relationship between neuropsychological profiles and lesional types emerges from this review of the literature. Non-fluent primary progressive aphasia, semantic dementia and progressive anarthria are usually associated with non-specific lesions and Pick-type pathology. Progressive disorders of episodic memory and progressive visuo-spatial deficits are more often related to AD. If adequate clinical characterisation can determine the underlying disorder, it appears even more important to establish the neuropsychological profile in patients with cortical degenerative disease. Progressive deficits of only one domain of cognition may well be due to preferential involvement of anatomically and functionally defined neural systems and could therefore be considered as "system atrophies". There remains no doubt that these syndromes are particularly well suited models for studies on the relationship between cerebral functions and their neural substrate.

A permanent pure amnestic syndrome of insidious onset related to Alzheimer's disease

A 55-year-old patient experienced a pure amnestic syndrome of insidious onset that worsened progressively. Subsequently, her memory disorder stabilized and remained her only cognitive impairment for several years. She ultimately developed more widespread cognitive decline and terminal dementia. Postmortem examination 18 years after the onset revealed numerous senile plaques and neurofibrillary tangles consistent with Alzheimer's disease. A permanent pure amnestic syndrome of insidious onset may represent a further type of focal cerebral degeneration.

[2 cases of frontal dementia with non-specific histological lesions: clinico-pathological and nosological discussion]

We report two cases of "frontal lobe dementia", patho-anatomically defined by non-specific as neuronal loss, gliosis and spongosis. The review of the literature permit to discuss the clinical picture of "fronto-temporal dementia" in regard to neuropathological basis. Further, the boundaries with Pick's disease, Kraepelin disease, subcortical gliosis and the "prions diseases" are considered. Without more precise nosological status, tacking in count the great variability of the clinical signs, we can concluded that, at present time, the term of frontal type dementia with "non-specific histological features", that underlines the neuropathological characteristics is the most appropriate to define this clinico-pathological entity.

[Early detection of morphologic-functional changes in the airways using a simple method of inhalation scintigraphy]

In order to validate a method of inhalation scintigraphy with 99mTc-labeled human serum albumin in the early diagnosis of morphologic-functional changes of the airways 35 volunteers and patients (12 healthy non-smokers and smokers each, 11 patients with bronchitis) were studied. Deposition of the aerosol immediately after inhalation was calculated quantitatively by a ROI technique and qualitatively (scoring of central deposition, homogeneity, and recognizability of lung outline). Additionally, the regional clearance of the inhaled aerosol was determined by continuous lung imaging up to 60 min (mainly regional mucociliary removal rates). Discrimination between healthy volunteers and patients with bronchitis was possible by means of deposition patterns immediately after inhalation. On the other hand, no differences could be recognized in this way between healthy non-smokers and smokers. Regional mucociliary removal was higher in non-smokers than in smokers, but there was no difference between smokers and patients with bronchitis.

Früherkennung von morphologisch-funktionellen Veränderungen der Atemwege durch eine einfache Methode der Inhalationsszintigraphie

Bei insgesamt 35 Probanden und Patienten (je 12 gesunde Nichtraucher und symptomlose Raucher und 11 Patienten mit Bronchitis) wurde die Wertigkeit der Inhalationsszintigraphie mit 99mTc-markiertem Humanalbumin zur Früherkennung von morphologisch-funktionellen Veränderungen der Atemwege untersucht. Das Depositionsmuster unmittelbar nach Inhalation (Primärdeposition = PD) wurde quantitativ mit einer ROI-Technik und qualitativ (visuelle Bewertung der zentralen Deposition, der Homogenität und der Lungenkontur) bewertet. Zusätzlich wurde die Abnahme der intrapulmonal deponierten Aktivität über 60 min registriert (Selbstreinigung der Lungen in erster Linie durch die mukoziliäre Clearance = MC). Anhand der PD konnte zwischen Patienten mit Bronchitis und lungengesunden Probanden unterschieden werden. Eine Diskriminierung zwischen Nichtrauchern und Rauchern war anhand der PD alleine nicht möglich. Dagegen unterschied sich das Probandenkollektiv der Raucher von den symptomlosen Rauchern durch eine bessere MC. Raucher und Patienten mit Bronchitis wiesen keinen Unterschied bei der MC auf.