Pietro Tiraboschi

Diagnosis and management of dementia with Lewy bodies Fourth consensus report of the DLB Consortium

The Dementia with Lewy Bodies (DLB) Consortium has refined its recommendations about the clinical and pathologic diagnosis of DLB, updating the previous report, which has been in widespread use for the last decade. The revised DLB consensus criteria now distinguish clearly between clinical features and diagnostic biomarkers, and give guidance about optimal methods to establish and interpret these. Substantial new information has been incorporated about previously reported aspects of DLB, with increased diagnostic weighting given to REM sleep behavior disorder and 123iodine-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. The diagnostic role of other neuroimaging, electrophysiologic, and laboratory investigations is also described. Minor modifications to pathologic methods and criteria are recommended to take account of Alzheimer disease neuropathologic change, to add previously omitted Lewy-related pathology categories, and to include assessments for substantia nigra neuronal loss. Recommendations about clinical management are largely based upon expert opinion since randomized controlled trials in DLB are few. Substantial progress has been made since the previous report in the detection and recognition of DLB as a common and important clinical disorder. During that period it has been incorporated into DSM-5, as major neurocognitive disorder with Lewy bodies. There remains a pressing need to understand the underlying neurobiology and pathophysiology of DLB, to develop and deliver clinical trials with both symptomatic and disease-modifying agents, and to help patients and carers worldwide to inform themselves about the disease, its prognosis, best available treatments, ongoing research, and how to get adequate support.

The importance of neuritic plaques and tangles to the development and evolution of AD

Objective: To determine the relation of neuritic plaques (NPs) and neurofibrillary tangles (NFTs) to the development and evolution of Alzheimer disease (AD). Methods: An autopsy series of 102 patients with dementia and pathologically confirmed AD and 29 normal control subjects (NCs) was studied. AD cases were stratified according to their last Mini-Mental State Examination (MMSE) before death as mild, moderate, severe, or very severe. NPs and NFTs were enumerated in the midfrontal (MF), inferior parietal (IP), superior temporal (ST), hippocampal (Hip), or entorhinal cortices using thioflavin-S preparations. Results: Most (87%) of the NCs had allocortical NFTs, whereas only a minority (37%) displayed neocortical NPs, and even fewer (19%) showed Hip NPs. In contrast, none of the NCs exhibited neocortical NFTs, except one case with a single ST tangle. However, neocortical NFTs were not detected in even 10% of the patients with AD and, in particular, were absent in nearly 50% of those with mild disease at death. Thus, their sensitivity as a marker of AD was lower than that of NPs, which, conversely, were found in all patients with AD. Comparing NCs and patients with mild AD, significant differences were found for numbers of NPs only. Across the AD groups, in contrast, although NP and NFT density increased with dementia severity, significant differences consistently emerged for NFTs alone. Conclusions: Deterioration in Alzheimer disease appears to be driven by neuritic plaques and neurofibrillary tangles at different stages of the disease. The significant increase in neuritic plaques, but not neurofibrillary tangles, in patients with even mild Alzheimer disease at death compared with normal control subjects suggests that only neuritic plaques are associated with the earliest symptoms of Alzheimer disease.

Cholinergic dysfunction in diseases with Lewy bodies

Objective: To evaluate cholinergic activity in diseases with Lewy bodies (LB; LB variant of AD [LBV], diffuse LB disease [DLBD], and Parkinson’s disease [PD]) to determine if 1) AD changes are requisite to cholinergic dysfunction, 2) cholinergic activity declines to the same extent in neocortical and archicortical areas, and 3) cholinergic loss is influenced by APOE genotype. Background: Like AD, diseases with LB are associated with decreased choline acetyltransferase (ChAT) activity. Increased APOE ε4 allele frequency has been reported in LBV. Whether APOE genotype affects cholinergic function in LBV remains unclear. Methods: An autopsy series of 182 AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer’s Disease criteria), 49 LBV, 11 PD, 6 DLBD, and 16 normal control (NC) subjects. APOE genotype and ChAT activity (nmol/h/100 mg) in the midfrontal and hippocampal cortices were determined. Results: Mean midfrontal ChAT activity was markedly reduced in diseases with LB (LBV: 53.3 ± 39.0; PD: 54.8 ± 35.7; DLBD: 41.3 ± 24.8) compared to NC (255.4 ± 134.6; p < 0.001) and AD (122.6 ± 78.9; p < 0.05). Among diseases with LB, midfrontal ChAT activity was decreased to a similar extent in patients with (LBV) and without (DLBD and PD) AD pathology. Although mean ChAT activity for LBV was less than half that for AD in the midfrontal cortex, it was similar to that for AD in the hippocampus (LBV: 243.5 ± 189.7; AD: 322.8 ± 265.6; p > 0.05). However, hippocampal ChAT activity for both AD and LBV was lower than that for NC (666.5 ± 360.3; p < 0.001). The ε4 allele dosage did not influence midfrontal ChAT activity in LBV. Conclusions: Marked losses in midfrontal ChAT activity occur in diseases with LB, independent of coexistent AD changes. A greater midfrontal, as opposed to hippocampal, cholinergic deficit may differentiate LBV from AD. The lack of a relationship between ε4 allele dosage and midfrontal ChAT activity suggests that other factors may play a role in its decline in LBV.

Impact of APOE genotype on neuropathologic and neurochemical markers of Alzheimer disease.

Background: The APOE ε4 allele has emerged as a major genetic factor for Alzheimer disease (AD), and its presence has been associated with an increase in β-amyloid senile plaques (SPs) and neuritic plaques (NPs). Whether it affects neurofibrillary tangle (NFT) accumulation or cholinergic losses in AD remains controversial. In contrast, the ε2 allele has been reported to decrease the risk for AD. However, its effect on neuropathologic and neurochemical markers of disease is unclear. Objective: To investigate the relationship between APOE genotype and both pathologic severity and cholinergic dysfunction in AD. Methods: In an autopsy series of 296 patients with AD, APOE genotype was determined in blood or postmortem brain tissue. NPs and NFTs were counted in the midfrontal (MF), inferior parietal (IP), and superior temporal (ST) cortices and the hippocampus. Choline acetyltransferase (ChAT) activity was assessed in the MF, IP, and ST cortices. Results: Compared with patients with no ε4 alleles, ε4 carriers (patients with either one or two ε4 alleles) did not differ significantly with regard to any pathologic or neurochemical measures, except for increased ST NPs. However, when cases were stratified into three groups according to the number of ε4 alleles, patients with two ε4 alleles had significantly more NPs and NFTs in all neocortical regions than those with either one or no ε4 alleles. The association of the ε4/4 genotype with neocortical pathologic severity remained significant even after adjusting for age at onset or age at death. In contrast, there were no significant group differences with regard to neocortical ChAT activity. When pathologic and neurochemical measures were compared between patients with the ε2 allele and those without, a strong relationship emerged between the ε2 allele and decreased NPs in all neocortical regions. Conclusions: The ε4 allele does not predict cholinergic decline in AD. Although the presence of a single ε4 allele appears to have no effect, the presence of two ε4 alleles is an important determinant of both NP and NFT accumulation. A putative protective role for the ε2 allele in AD may be mediated by reduced plaque burden.

The decline in synapses and cholinergic activity is asynchronous in Alzheimer's disease.

Objective: To determine the timing of cholinergic loss and reduction of synapses in AD. Background: Decrements in neocortical synapses and cholinergic function occur in AD and correlate with cognitive decline. However, how early in the disease process these changes appear remains unclear. Methods: An autopsy series of 89 demented patients with pathologically confirmed AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer’s Disease criteria) and 18 normal control subjects (NC). The AD cases were stratified according to their last Mini-Mental State Examination (MMSE) score prior to death as mild (MMSE = 20; n = 14), moderate (MMSE = 10 to 19; n = 20), severe (MMSE = 1 to 9; n = 29), and very severe (MMSE = 0; n = 26). Midfrontal (MF) synapse density was assessed by dot-immunobinding assay for synaptophysin (Syn), and MF choline acetyltransferase (ChAT) activity was determined using standard protocols. Results: Compared with those in NC, neither Syn nor ChAT was appreciably reduced in patients with mild AD at death. Decline of ChAT was significant only in AD patients who died in the late stages of the disease and was maximal in those who had more severely deteriorated. In contrast, decline of Syn was significant and almost maximal in patients in intermediate or moderate stages. Consequently, the last MMSE score prior to death correlated more strongly with ChAT than Syn when the AD cohort included more impaired patients (r = 0.46 versus 0.40). The reverse occurred when only less impaired patients (MMSE = 10) were included in the analyses (r = 0.28 versus 0.64). There was only a modest correlation between Syn and ChAT activity. Conclusions: The results imply an asynchronous pattern of decline of synapses and cholinergic activity, with Syn loss preceding ChAT decrements. However, neither MF synapse reduction nor cholinergic dysfunction appears to be an early event in AD.

Alzheimer disease without neocortical neurofibrillary tangles “A second look”

Objective: To compare the clinical and pathologic features of plaque only Alzheimer disease (POAD) with plaque and tangle Alzheimer disease (PTAD). Methods: An autopsy series of 16 patients with POAD and 32 subjects with PTAD on whom extensive antemortem neuropsychological testing was available. Plaques, tangles, and cerebral amyloid angiopathy were examined in the neocortex and hippocampus using thioflavin S staining. In addition, immunocytochemical analysis with AT8 for phosphorylated tau was performed. Midfrontal (MF) synaptic density, MF choline acetyltransferase (ChAT) activity, and apolipoprotein E genotyping were also assessed. Results: Initial neuropsychological test scores and rates of cognitive decline on the Mini-Mental State Examination and Blessed Information-Memory-Concentration were similar between the two groups. However, compared to PTAD, POAD patients tended to deteriorate more slowly on the Mattis Dementia Rating Scale. Furthermore, they were somewhat less impaired on all these measures at last examination. There was an older age at onset and death, and a trend toward a shorter disease duration, in POAD compared to PTAD patients. POAD subjects, by definition, had no neocortical neurofibrillary tangles (NFT) (Braak stages IV or less). In addition, they also had fewer hippocampal NFT, fewer neuritic plaques, and higher mean MF ChAT activity than PTAD subjects. On the other hand, the two groups did not differ significantly in brain weight or MF synaptic density. Although lacking overt tangle formation, the POAD group displayed abnormal phosphorylated tau immunoreactivity in neocortical pyramidal neurons. Conclusions: Dementing syndromes virtually indistinguishable from each other can, and do, develop in the presence or absence of neocortical NFT. Patients without neocortical NFT are, on average, older at disease onset and death, and show a trend toward a shorter disease duration with somewhat slower deterioration. Although neocortical NFT per se are not obligatory for the development of clinical dementia, more subtle neocortical cytoskeletal tau pathology may contribute to cognitive decline in these subjects.

Nicotinic receptor losses in dementia with Lewy bodies: comparisons with Alzheimer’s disease ☆

We sought to delineate differences between alpha7 nicotinic acetylcholine receptor (nAChR) levels in Alzheimers disease (AD), dementia with Lewy bodies (DLB) and age matched controls, as well as the correlations between alpha7 or non-alpha7 nAChR levels and synaptophysin (Syn) or choline acetyltransferase (ChAT) in DLB. Mean bungarotoxin (Bgt) binding was 2.7 - 1.1 for controls, 2.4 +/- 1.0 for AD and 1.4 +/- 0.5 for DLB. There were significant decreases in Bgt binding for the DLB group compared to either controls or AD. Mean epibatidine (Epi) binding was 14.8 +/- 3.2 for controls, 6.3 +/- 3.2 for AD and 7.1 +/- 2.4 fmoles/mg protein for DLB. Epi binding in both the AD and DLB groups was significantly lower than in the controls. Although Syn loss correlated with the decrease in Epi binding in both diseases, declining ChAT levels correlated with Epi binding only in DLB. These data demonstrate a different pattern of nAChR loss in AD and DLB that may, in part, explain some of the differences in the two phenotypes.

E4 allele dosage does not predict cholinergic activity or synapse loss in Alzheimer’s disease

Objective: To investigate the relationship between apolipoprotein E (APOE) genotype and both cholinergic dysfunction and synapse loss in AD. Background: A reduction in neocortical synapses and marked losses in the cholinergic system occur in AD. It has been suggested that the number of APOE ε4 alleles is inversely related to choline acetyltransferase (ChAT) activity, thereby influencing cholinergic function. Whether APOE genotype may influence neocortical synapse loss remains unclear. Methods: An autopsy series of 182 patients with AD (National Institute on Aging and Consortium to Establish a Registry for Alzheimer’s Disease criteria) and 16 normal controls (NC). APOE genotype was determined in blood samples or in postmortem brain tissue. Midfrontal synapse counts (AU/μg) were quantified by a dot-immunobinding assay for synaptophysin (Syn). Midfrontal ChAT activity (nmol/h/100 mg) was assessed using standard assays. Results: Mean midfrontal ChAT activity and Syn were both significantly reduced in patients with AD compared with NC. The relationship between ChAT activity and number of ε4 allele copies in AD was complex, with ChAT activity lower in patients with either two or no ε4 alleles compared with those with one ε4 allele. There was no relationship between APOE genotype and synapse loss in AD. Syn density was almost identical across the three genotypes. Conclusions: Unlike other studies, we failed to detect a linear relationship between ChAT activity and number of ε4 allele copies in the midfrontal cortex of this large sample of patients with AD. Our data also show that the presence of ε4 allele does not influence midfrontal synapse loss in AD. This suggests that factors other than APOE genotype may be operative in the decline in midfrontal cholinergic function and synapses seen in AD.

Smoking affects the phenotype of Alzheimer disease

Because epidemiologic and in vitro evidence conflict, the authors studied the association between smoking and Alzheimer disease (AD) in 46 never, 47 former, and 15 active smokers with AD followed to autopsy. Disease parameters were examined by smoking status and amount smoked in bivariate tests and in multivariate models controlling for age, sex, education, and APOE status. Smoking status was not associated with cognitive or neuropathologic measures. However, active smokers were significantly younger at death and higher levels of smoking were associated with shorter disease duration.

Updates on Somatoform Disorders (SFMD) in Parkinson's Disease and Dementia with Lewy Bodies and discussion of phenomenology

Somatoform Disorders (SFMD) were recently described in Parkinson Disease (PD) and Dementia with Lewy Bodies (DLB). The present paper updates the observations in our cohort of patients and further details clinical phenomenology. Of 3178 patients consecutively referred to our Institutions from 1999, 1572 subjects had neurodegenerative diseases and 1718 psychiatric disorders. After 2-9 years of follow up, 488 patients were labelled as PD, 415 as Alzheimer Disease, 162 as DLB, 48 as Progressive Supranuclear Palsy, 48 as Multiple System Atrophy and 49 as Fronto-Temporal Dementia. The frequency of SFMD (DSM-IV-TR criteria) was determined in each diagnostic category by direct observation of SFMD symptoms, psychiatric interviews, SCL 90Rss, collection of previous general practitioners and hospital charts. The frequency of SFMD was considerably higher in DLB (29 patients, 18%) and PD (37 patients, 7.5%) than in any other group (0-2%). The frequency of SFMD in psychiatric patients was 2%. SFMD in PD and DLB were characterised by motor and non-motor patterns and were often accompanied by catatonic signs consisting of posturing stereotypies and negativism (55%). SFMD symptoms preceded PD motor signs by 6 months-5 years in 92% of the 29 DLB and 37 PD patients and in 70% SFMD were recurrent at follow-up. In 93% of these patients, hypochondria was a preceding or concomitant background.