A functional 5HT2A receptor polymorphism (His452Tyr) and memory performances in Alzheimer's disease

The functional His452Tyr polymorphism in the 5HT2A receptor has been described to be associated with verbal memory in healthy adults, with worse episodic memory performances in Tyr452 (T) carriers. The aim of our study was to investigate a possible effect of this polymorphism on memory performances in Alzheimer disease (AD). We enrolled 169 patients affected by probable AD. 5HT2A genotype was determined as previously described. According to their genotype, patients were divided in T carriers ( n = 111) and non-carriers ( n = 69). We evaluated the possible effect of 5HT2A polymorphism on verbal memory tasks. A one-way MANOVA analysis did not show a positive interaction between the two groups ( p > 0.05) at the baseline and at the follow-up. Nevertheless, the analyses of the single-task effect showed lower performances for non-T carriers only in Rey's recognition task. Recent data reported poorer memory performances in healthy subjects carrying the T variant, in age-dependent manner (no differences between T vs. nT carriers were observed for age >50 years). In our AD sample, we did not find significant differences in verbal memory scores in T vs. nT carriers while a significant difference was found only in attentional task. At variance with that in healthy subjects, no correlation has been found between memory profiles of AD patients and His452Tyr polymorphism.

BuChE K variant is decreased in Alzheimer's disease not in fronto-temporal dementia

Alzheimer's disease (AD) is characterized by a significant reduction in AcetylCholinesterase and an increase in ButyrylCholinesterase (BuChE) activity. The existence of polymorphic regions on the BuChE gene has been previously described; the most frequently found polymorphism is the so-called K variant, which leads to a 30% decreased enzymatic activity. Different studies reported a positive association between K variant and AD, strongest among late-onset AD and Apolipoprotein E (APOE) e4 carriers. We analyzed APOE and BuChE polymorphisms in 167 AD and 59 fronto-temporal dementia (FTD) patients compared with 129 healthy controls (HC). We reported a significantly lower frequency of the BuChE K variant in AD compared with HC and FTD and a significant increased frequency of the K variant in FTD. These results are in agreement with the known increase of the BuChE activity in AD and support the evidence of different molecular pathways involved in the pathogenesis of AD and FTD.

Effect of a CYP2D6 polymorphism on the efficacy of donepezil in patients with Alzheimer disease

OBJECTIVE

To evaluate the influence of the single nucleotide polymorphism rs1080985 in the cytochrome P450 2D6 (CYP2D6) gene on the efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD).

METHODS

This was a multicenter, prospective cohort study of 127 white patients with AD according to the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association Work Group criteria. Patients were treated with donepezil 5-10 mg/daily for 6 months. Cognitive and functional statuses were evaluated at baseline and at 6-month follow-up. Response to therapy was defined according to the National Institute for Health and Clinical Excellence criteria. Compliance and drug-related adverse events were also evaluated. The analyses identifying the CYP2D6 and APOE polymorphisms were performed in blinded fashion.

RESULTS

At 6-month follow-up, 69 of 115 patients (60%) were responders and 46 patients (40%) were nonresponders to donepezil treatment. A significantly higher frequency of patients with the G allele of rs1080985 was found in nonresponders than in responders (58.7% vs 34.8%, p = 0.013). Logistic regression analysis adjusted for age, sex, Mini-Mental State Examination score at baseline, and APOE demonstrated that patients with the G allele had a significantly higher risk of poor response to donepezil treatment (odds ratio 3.431, 95% confidence interval 1.490-7.901).

CONCLUSIONS

The single nucleotide polymorphism rs1080985 in the CYP2D6 gene may influence the clinical efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD). The analysis of CYP2D6 genotypes may be useful in identifying subgroups of patients with AD who have different clinical responses to donepezil.

Clusters of cognitive and behavioral disorders clearly distinguish primary progressive aphasia from frontal lobe dementia, and Alzheimer's disease

BACKGROUND/AIMS

Frontal lobe dementia (FLD) and primary nonfluent progressive aphasia (PnPA) are two forms of frontotemporal lobe degeneration. The relationship between these conditions remains unclear. Our study aimed to better define the behavioral and cognitive clusters characterizing PnPA patients.

METHODS

We cognitively and behaviorally evaluated three groups of newly diagnosed patients affected by Alzheimer's disease (AD, n=20), FLD (n=22) and PnPA (n=10), in order to assess the cognitive-behavioral pattern of PnPA, compared to both FLD and AD.

RESULTS

We found, as expected, worse performances in episodic memory in AD, of both the verbal fluency and naming tasks in PnPA, while FLD mainly showed behavioral disorders associated with an unremarkable deficit in the executive tasks. PnPA was not characterized by any significant behavioral disorders. Factor analysis-extracted three main factors ('mnesic', 'behavioral' and 'linguistic') clearly correlated to each group. A discriminant analysis based on the extracted factors correctly classified 84.6% of all patients.

CONCLUSION

The evidence of a characteristics cognitive profile, without any significant behavioral changes, highlights that PnPA is different from other forms of frontotemporal lobe degeneration regarding both the cognitive and behavioral patterns; thus, it should be considered independently in further studies.

The Missing ApoE Allele

The human apoE gene (APOE, GenBank accession AF261279) shows a common polymorphism, with the three epsilon2, epsilon3 and epsilon4 alleles resulting from the haplotypes of two C-->T SNPs. However, whereas the three common T-T, T-C and C-C haplotypes corresponding to the epsilon2, epsilon3 and epsilon4 alleles are well known, the last C-T haplotype (GenBank accession AY077451), encoding a fourth apoE allele, has rarely been reported. We detected this fourth allele in a Caucasian patient with motor neuron disease (MND). According to the literature we refer to this allele as epsilon3r. Although several explanations may be proposed for its formation, the existence of this fourth allele is consistent with the evolutionary hypothesis generally accepted for the apoE alleles. The rarity and physiological role of epsilon3r remains to be explained, and requires further investigation.

Apolipoprotein E epsilon4 allele differentiates the clinical response to donepezil in Alzheimer's disease

The existence of an association between apolipoprotein E (APOE) and Alzheimer's disease (AD) has been reported in several studies. The possession of an ApoE epsilon4 allele is now considered a genetic risk factor for sporadic AD. There has been a growing agreement about the role exerted by the ApoE epsilon4 allele on the neuropsychological profile and the rate of cognitive decline in AD patients. However, a more controversial issue remains about a possible influence of the APOE genotype on acetylcholinesterase inhibitor therapy response in AD patients. In order to address this issue, 81 patients diagnosed as having probable AD were evaluated by a complete neuropsychological test battery at the time of diagnosis (baseline) and after 12-16 months (retest). Patients were divided into two subgroups: (1) treated with donepezil at a dose of 5 mg once a day (n = 41) and (2) untreated (n = 40). Donepezil therapy was started after baseline evaluation. The APOE genotype was determined according to standardized procedures. We evaluated the possible effect of the APOE genotype on the neuropsychological tasks in relation to donepezil therapy. The statistical analysis of the results showed a global worsening of cognitive performances for all AD patients at the retest. Differences in the clinical outcome were analysed in the four subgroups of AD patients for each neuropsychological task. ApoE epsilon4 carriers/treated patients had improved or unchanged scores at retest evaluation for the following tasks: visual and verbal memory, visual attention and inductive reasoning and Mini Mental State Examination. These results indicate an effect of donepezil on specific cognitive domains (attention and memory) in the ApoE epsilon4 carriers with AD. This might suggest an early identification of AD patients carrying at least one epsilon4 allele as responders to donepezil therapy.

The role of brain infarcts and hippocampal atrophy in subcortical ischaemic vascular dementia

We investigated if, in patients with vascular lesions, the variable that best discriminated demented from non-demented patients was the severity of the vascular pathology or the degree of hippocampal atrophy. A total of 39 patients multiple subcortical infarcts, who could be considered as possible vascular dementia with small vessel pathology, with underwent a neuropsychological study and brain magnetic resonance imaging (MRI) DSM IV criteria supported by neuropsychological data were used to distinguish demented from non-demented patients. The MRI study took into account the degree of hippocampal atrophy (hippocampal height and interuncal distance) and the severity of vascular pathology (number of brain infarcts). The distribution of lesions and a factor analysis showed that hippocampal atrophy is a better predictor of dementia than the number of brain infarcts. Multiple subcortical infarcts alone are probably not able to cause clinical dementia but the presence of vascular lesions increases the expression of concomitant Alzheimer's disease.

Alzheimer disease risk associated withAPOE4is modified bySTHgene polymorphism

The association of the STH gene polymorphism with Alzheimer disease (AD) is debated. In the analysis of two genetically and diagnostically distinct groups of Alzheimer patients from the USA and Italy, the authors did not find an association with the STH polymorphism. However, the APOE-4-associated risk of AD greatly increased if the STH-G allele was also present. The STH-G allele appears to be a risk modifier for AD.

Noninvasive in vivo assessment of cholinergic cortical circuits in AD using transcranial magnetic stimulation

BACKGROUND

A recently devised test of motor cortex excitability (short latency afferent inhibition) was shown to be sensitive to the blockade of muscarinic acetylcholine receptors in healthy subjects. The authors used this test to assess cholinergic transmission in the motor cortex of patients with AD.

METHODS

The authors evaluated short latency afferent inhibition in 15 patients with AD and compared the data with those of 12 age-matched healthy controls.

RESULTS

Afferent inhibition was reduced in the patients (mean responses +/- SD reduced to 85.7% +/- 15.8% of the test size) compared with controls (mean responses +/- SD reduced to 45.3% +/- 16.2% of the test size; p < 0.001, unpaired t-test). Administration of a single oral dose of rivastigmine improved afferent inhibition in a subgroup of six patients.

CONCLUSIONS

The findings suggest that this method can be used as a noninvasive test of cholinergic pathways in AD. Future studies are required to evaluate whether short latency afferent inhibition measurements have any consistent clinical correlates.

The Apolipoprotein E genotype in patients affected by syndromes with focal cortical atrophy

The role of the Apolipoprotein E (APOE) alleles in syndromes associated with focal cerebral atrophy (fronto-temporal dementia, primary progressive aphasia, corticobasal degeneration) is still controversial. We studied the APOE allele distribution in 39 patients with clinically diagnosed syndromes associated with focal cerebral atrophy (FCA), in 50 patients with early-onset probable Alzheimer's disease (EOAD), and in 60 patients with late-onset probable AD (LOAD). The APOE genotype was determined from a blood sample, using polymerase chain reaction and restriction enzyme digestion. The APOE epsilon4 allele frequency was significantly higher in the EOAD (21.0%) and LOAD (33.3%) groups, but not in the FCA group (5.1%), as compared with controls. In our population, the epsilon2 allele frequency was significantly higher in patients with FCA (12.8%) than in controls (4.8%). These results show that the APOE epsilon4 allele is not a risk factor for syndromes associated with FCA. The potential role of the epsilon2 allele in these syndromes needs further investigation.

Does PRNP gene control the clinical and pathological phenotype of human spongiform transmissible encephalopathies?

BACKGROUND

Human spongiform transmissible encephalopathies (TSE) are a group of neurodegenerative diseases caused by a transmissible not yet recognized agent; their distinctive neuropathological features are astrocytosis, spongiform lesions of the neuropil, neuronal loss and occasionally amyloid plaques in the cortical and subcortical gray matter. TSE are biochemically characterized by the deposition in the nervous system of an amyloid-type protein, PrPres derived from the post-translational modification of a normal protein, PrPsen. The expression of this protein is controlled by the PRNP gene mapped on chromosome 20 in man. A number of point mutations of the PRNP gene have been described in the familial forms of these TSE. Some of these mutations have been associated with differences in the phenotypic expression of the disease.

MATERIAL AND METHODS

This study was designed to verify whether it was possible to identify a selective phenotype depending upon a given PRNP modified genotye; for this purpose, a group of familial TSE cases (CJD 210ILE, CJD 201LYS, FFI 178ASN) were selected and their neuropathological profiles have been compared with those of a large series of sporadic CJD cases.

RESULTS

No significant differences were found between the topography and severity of lesions in the cerebral cortex, cerebellum, hippocampus, basal ganglia and thalamus between the two groups. Two differences were found: the clinical duration of the disease which appeared significantly (p = 0.02) shorter in the 210ILE-mutated cases compared to that of non-mutated sporadic cases. The highly selective vulnerability of thalamus in FFI showing a severe pathology especially in its dorso-medial part in comparison with that of the sporadic CJD cases.

CONCLUSION

The results of this study confirm that the different polymorphism at codon 129 of the PRNP gene, which could be involved in the structural "domains" of human PrP, might modulate the pathological phenotype of TSE.

European surveillance on Creutzfeldt-Jakob disease: a case-control study for medical risk factors

Medical risk factors for Creutzfeldt-Jakob disease (CJD) were analyzed in a prospective ongoing case-control study based on European CJD surveillance. Detailed data on past and recent medical history were analyzed in 405 cases and controls matched by sex, age, and hospital. Data were correlated with polymorphism at codon 129 of the prion protein gene. Our analysis did not support a number of previously reported associations and failed to identify any common medical risk factor for CJD. Although not statistically significant, brain surgery was associated with an increased risk of CJD. A detailed medical history should be obtained in every suspected CJD case in order to identify iatrogenic sources of CJD.

Acute hemorrhagic leukoencephalitis in patients with acute myeloid leukemia in hematologic complete remission

The authors describe the cases of three patients affected by acute myeloid leukemia, in complete remission, who rapidly developed neurologic symptoms leading to death. Neither clinical characteristics, nor radiological or microbiological procedures, allowed an etiological diagnosis of the neurologic syndrome. Post-mortem examination of the brain showed both macroscopic and microscopic findings compatible with acute hemorrhagic leukoencephalitis. The difficulty in distinguishing this entity from other CNS disease-related complications (e.g. leukemia infiltration, drug toxicity, hemorrhages) should not lead to an underestimation of the true incidence of this complication. We believe that with more attention to the possibility of this complication there would probably be both a greater possibility of collecting clinical informations about the real impact of this dramatic disease and a stronger hope of finding the right treatment for it.

Oxidative stress and overexpression of manganese superoxide dismutase in patients with Alzheimer's disease

Substantial evidence supports the hypothesis that oxygen free radicals are involved in various neurodegenerative disorders. To assess the presence of oxidative stress in Alzheimer's disease (AD) we examined the activity of the enzyme copper-zinc superoxide dismutase (CuZnSOD) in red blood cells, the levels of the mitochondrial inducible enzyme manganese superoxide dismutase (MnSOD) mRNA in lymphocytes, and the total radical-trapping antioxidant capacity (TRAP) in plasma of AD patients and in a group of age-matched non-demented controls. We found that CuZnSOD activity (P < 0.01 vs. controls) was significantly increased as well as the MnSOD mRNA levels while the total antioxidant status (P < 0.001 vs. controls) was decreased in AD patients. These findings support the role of oxidative alterations in the pathogenetic mechanism underlying AD neurodegeneration.

Apolipoprotein E genotype in sporadic early- and late-onset Alzheimer's disease

The 84 isoform of apolipoprotein E (ApoE) has been proposed as a risk factor for Alzheimer's disease (AD), while the possible role of the epsilon2 allele in AD is controversial. We have studied the ApoE genotype in 38 patients with early-onset AD (EOAD) and in 43 patients with late-onset AD (LOAD). In the EOAD group we observed a significant increase of epsilon4 allele frequency as compared with normal controls, while there was a more than 3-fold decrease of epsilon2 allele frequency that did not reach statistical significance. In the LOAD group we found a highly significant increase of epsilon4 allele frequency as compared with normal controls, while there was a significant decrease of epsilon2 allele frequency. In both the EOAD and LOAD groups, no significant difference was observed between epsilon4 carriers and epsilon4 noncarriers as for age at disease onset, disease duration, and Mini-Mental State score at observation. However, in both EOAD and LOAD groups a statistical trend towards a longer disease duration was observed in epsilon4 carriers. In both the EOAD and LOAD groups, disease severity was compared in epsilon4 carriers versus epsilon4 noncarriers by means of analyses of covariance, with disease duration as covariate. No significant difference between epsilon4 carriers and epsilon4 noncarriers was observed in both EOAD and LOAD. The results of the present study confirm that epsilon4 allele seems to be associated with an increased risk for sporadic AD, while the significant decrease of epsilon2 allele frequency in the LOAD group supports the hypothesis of a possible protective role of epsilon2 allele in AD.

Case-control study of risk factors of Creutzfeldt-Jakob disease in Europe during 1993-95. European Union (EU) Collaborative Study Group of Creutzfeldt-Jakob disease (CJD)

BACKGROUND

Creutzfeldt-Jakob disease (CJD) is a transmissible spongiform encephalopathy. Genetic and iatrogenic forms have been recognised but most are sporadic and of unknown cause. We have studied risk factors for CJD as part of the 1993-95 European Union collaborative studies of CJD in Europe.

METHODS

The 405 patients with definite or probable CJD who took part in our study had taken part in population-based studies done between 1993 and 1995 in Belgium, France, Germany, Italy, the Netherlands, and the UK. Data on putative risk factors from these patients were compared with data from 405 controls.

FINDINGS

We found evidence for familial aggregation of CJD with dementia due to causes other than CJD (relative risk [RR] 2.26, 95% CI 1.31-3.90). No significant increased risk of CJD in relation to a history of surgery and blood transfusion was shown. There was no evidence for an association between the risk of CJD and the consumption of beef, veal, lamb, cheese, or milk. No association was found with occupational exposure to animals or leather. The few positive findings of the study include increased risk in relation to consumption of raw meat (RR 1.63 [95% CI 1.18-2.23]) and brain (1.68 [1.18-2.39]), frequent exposure to leather products (1.94 [1.13-3.33]), and exposure to fertiliser consisting of hoofs and horns (2.32 [1.38-2.91]). Additional analyses, for example stratification by country and of exposures pre-1985 and post-1985, suggest that these results should be interpreted with great caution.

INTERPRETATION

Within the limits of the retrospective design of the study, our findings suggest that genetic factors other than the known CJD mutations may play an important part in CJD. Iatrogenic transmission of disease seems rare in this large population-based sample of patients with CJD. There is little evidence for an association between the risk of CJD and either animal exposure, or consumption of processed bovine meat or milk products for the period studied.

Resistance of the hippocampus in Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) belongs to the group of subacute spongiform encephalopathies of animals and man. Their pathogenesis is certainly related to the formation and deposition in the brain of an amyloid-type specific protein, named PrPres (prion protein-resistant). The neuropathological topography of CJD does generally admit that archicortex is relatively spared, but only a few papers have been devoted to this issue. A neuropathological study of CJD cases divided in sporadic, familial, and iatrogenic forms of the disease has been carried out, taking into consideration the archipallial lesions in relation to different clinical and neuropathological parameters. The pyramidal cell layer of CA1 of all CJD cases did not show any major loss of neurons in comparison to that observed in other cortical fields of the limbic cortex (mainly in the presubicular and entorhinal cortex) and of the neocortex. Spongiogliotic reaction was observed only in the stratum radiatum and molecularis lacunosum in a iatrogenic case of the disease. The findings observed in the pyramidal cell layer of CA1 were neither related to the clinical duration of the disease nor to the severity of the lesions found in other limbic and neocortical areas. The results of this study support the view of no close relationships between the demential syndrome typically related to the clinical onset and progression of CJD, and the structural damage of the hippocampus classically involved in the pathogenetic mechanism of the amnestic syndrome related to the clinical presentation and course of more common forms of dementias, such as Alzheimer's disease.

[Consensus report: tissue handling in suspected Creutzfeldt-Jakob disease and other spongiform encephalopathies (prion diseases) in the human. European Union Biomed-1 Concerted Action]

Despite many sensational and intimidating reports in the mass media, transmissible spongiform encephalopathies (prion diseases) are not contagious in the usual sense. Successful transmission requires both specific material (an affected individual's tissue, from or adjacent to CNS) and specific modes (mainly penetrating contact with the recipient). Nevertheless, specific safety precautions are mandatory to avoid accidental transmission and to decontaminate any infectivity. The autopsy is essential for definite diagnosis of these disorders. Recommendations are given here for safe performance of the autopsy, for neuropathology service and appropriate decontamination; they are based on the current literature and on precautions taken in most laboratories experienced in handling tissue from transmissible spongiform encephalopathies. In essence, special care must be taken to avoid penetrating wounds, possible contamination should be kept to a minimum, and potentially infectious material must be adequately decontaminated by specific means. The full English text of this Consensus Report was published in Brain Pathology 5: 319-322 (1995).

Creutzfeldt-Jakob disease in an Iranian: the first clinico-pathologically described case

This is the first report of a definite case of Creutzfeldt-Jakob disease in an Iranian and it has been confirmed by a neuropathological study and by the immunoelectrophoretic demonstration of PrP, the pathological amyloid protein specific to the spongiform encephalopathies. The clinical course and the topography and severity of brain pathology classify this case as of panencephalopathic type and support the view of different phenotypic expressions of CJD in relation to the existence of multiple strains of the causative agent.

Polymorphisms of the prion protein gene in Italian patients with Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a transmissible neurodegenerative disorder characterized by the accumulation of the amyloid protein PrP in the CNS. Two coding polymorphisms of the PrP gene (PRNP) are a methionine (Met) to valine (Val) change at codon 129, and a deletion in the octapeptide coding region. In the United Kingdom, homozygosity at codon 129 appears to be associated with a predisposition to develop CJD. However, in Japan, where allelic frequencies and genotype distribution are significantly different, such an association has not been demonstrated. To determine whether such deletion(s) or codon 129 polymorphisms of PRNP predispose to the development of CJD in Italian patients, 31 sporadic CJD patients with no known PRNP mutations, and 186 unrelated control subjects were studied. Genotypic frequencies at codon 129 in these Italian CJD patients revealed a significant excess of methionine alleles, and a different genotype distribution in comparison with the normal Italian population. Deletions of a 24-bp segment located in the PrP octapeptide coding region were found in two control subjects, but in none of the sporadic CJD patients. These data suggest that Met homozygosity at codon 129 may contribute, with other environmental or endogenous factors, to CJD development.

Iatrogenic Creutzfeldt-Jakob disease: an example of the interplay between ancient genes and modern medicine

We tested DNA from 15 centrally infected cases of iatrogenic Creutzfeldt-Jakob disease (CJD) (dura mater or corneal homografts and stereotactic EEG electrodes), 11 peripherally infected cases (native human growth hormone or gonadotrophin), and 110 control individuals for the presence of mutations in the chromosome 20 amyloid gene. No patient or control had any of the known pathogenic point or insert mutations found in familial disease, but allelic homozygosity at polymorphic codon 129 was present in all but two (92%) of the 26 patients, compared with 54 (50%) of the 110 controls (p < 0.001). Pooled data from all identified and tested cases of iatrogenic disease yielded a worldwide total of 56 patients, of whom all but four were homozygous at codon 129 (p < 0.001). These findings support the thesis that homozygosity at codon 129 enhances susceptibility to iatrogenic infections of both central and peripheral origin, with evident implications for the population of dura mater homograft and pituitary hormone recipients whose lives have been complicated by the possibility of exposure to the infectious agent of CJD.

A new point mutation of the prion protein gene in Creutzfeldt-Jakob disease

Complete sequencing of the prion protein open reading frame of a 68-year-old woman affected by a familial form of Creutzfeldt-Jakob disease (CJD) revealed a new mutation at codon 210 resulting in the substitution of isoleucine for valine. Moreover, a new 24-bp deletion encompassing codons 54 to 61 or 62 to 69 was found in the other allele. Four of the 17 asymptomatic relatives tested carry the 210 mutation. Two of them were 81 and 82 years old. Four of 22 patients with CJD whose recorded familial history was negative for demented illnesses, but none of 103 healthy control subjects, tested positive for the 210 mutation. These data suggest that the 210 mutation is associated with CJD, but that environmental factors or incomplete penetrance may contribute to the development of the disease. This finding also suggests that in Italy, familial CJD is more common than previously reported.

White matter lesions in Creutzfeldt-Jakob disease. A short review

This short review takes in consideration the role played by the cerebral white matter in Creutzfeldt-Jakob disease (CJD) and analyzes three different hypotheses on the meaning of the involvement of the white matter only as secondary phenomenon or as primary neuropathological damage related to the causative agent(s) of the disease.

Amphotericin B treatment dissociates in vivo replication of the scrapie agent from PrP accumulation

Scrapie and related animal and human disorders are neurodegenerative diseases characterized by the formation of a modified, partly proteinase-resistant protein (PrP) of the host, which tends to aggregate as amyloid fibrils and accumulate in the brain of infected individuals. There is a general consensus that the pathological form of PrP (PrPSc) is essential for the clinical appearance of the disease, but whether it is part of the scrapie agent or a by-product of viral infection is still controversial. Here we report that treatment of scrapie-infected hamsters with amphotericin B delays the accumulation in the brain of the proteinase-resistant portion of PrPSc by about 30 days without affecting scrapie replication. The consequence is that hamsters treated with amphotericin B developed clinical signs of disease later than infected controls. We argue that the proteinase-resistant portion of PrPSc is necessary for the development of the disease but that it is unlikely to be essential for scrapie replication.

Sulphate polyanions prolong the incubation period of scrapie-infected hamsters

The effect of the organic sulphated polyanions, pentosan sulphate (SP54), dextran sulphate 500 (DS500) and suramin, have been tested on golden Syrian hamsters infected with the 263K strain of scrapie by the intraperitoneal (i.p.) or the intracerebral route. SP54 had the greatest effect in prolonging the incubation period of the disease when administered within 2 h of the i.p. inoculum. The same amount of SP54 given 24 h after scrapie inoculation had a potent effect in some animals and no effect in others. This result suggests that SP54 inhibits the uptake of the scrapie agent into the nerve endings and/or carrier cells at the site of the inoculum, i.e. the peritoneum, and that this event occurs in about 24 h. DS500 had a similar although less potent effect (22.4 days delay during the incubation period) than SP54 (54.4 days) when administered within 2 h of scrapie injection by the i.p. route, and suramin had only a minimal effect (10 days). This study suggests that treatment of scrapie and related spongiform encephalopathies of animals and man is possible only before the agent has reached the clinical target areas of the brain.

Experimental drug treatment of scrapie: a pathogenetic basis for rationale therapeutics

Pharmacological treatment with polyanions or amphotericin B in hamsters with experimental scrapie reveals that it is possible to delay the appearance of the disease only when the drug is given before the invasion of the agent into the clinical target areas of the brain. We suggest such early treatment may be possible for individuals at high risk of acquiring the disease, such as healthy mutation-positive relatives of patients with familial Creutzfeldt-Jakob disease or Gerstmann-Sträussler syndrome, or recipients of potentially contaminated pituitary-extracted human growth hormone.

The nucleus basalis of Meynert in parkinsonism-dementia of Guam: a morphometric study

The nucleus basalis of Meynert (nbM) was studied morphometrically in three Guamanians with parkinsonism-dementia (PD) and in two Guamanian and two non-Guamanian controls. Paraffin-embedded blocks of the nbM were serially sectioned (20 microns thick) at increments of 200 microns so that a total of 24 sections (eight each from the anterior, intermediate and posterior sectors of the nbM) were studied. The mean cell density was determined for each sector and the diameter of 50 neurons, randomly chosen in the region of apparent maximal density, was calculated. A decrease of the mean cell density, due to the loss of neurons with diameters larger than 20 microns, was found in the PD cases compared to the controls. Two PD patients exhibited striking neuronal loss (65-95%) with predominant involvement of the intermediate and posterior sectors, while the third case showed only minimal neuronal loss in these sectors (15-40%). In both Guamanian and non-Guamanian controls large neurons (diameters greater than or equal to 20 microns) exceeded small neurons while the reverse was true in all sectors of the nbM for the PD cases. These data, while confirming a previous study reporting neuronal loss in the nbM of PD patients, underline the importance of detailed morphometric analysis of the different sectors of the nbM to recognize those patients in whom lesions are not uniformly distributed.

A retrospective study of Creutzfeldt-Jakob disease in Italy (1972-1986)

In a retrospective study of Creutzfeldt-Jakob disease (CJD) in Italy from 1972 to 1986, we found 79 cases which fulfilled the diagnostic criteria for CJD. The annual mortality rate was 0.09 cases per million inhabitants. In this series the female to male ratio was 2.59, a value significantly higher than that found in Italian population (1.05). The mean age at death was 62.1 +/- 9.4 years and the mean duration of the disease was 5.3 +/- 3.0 months. No familial cases of CJD were found in our series. Mental deterioration was present in all of our cases, myoclonus in 85% and the other clinical signs were present at a lower rate. Periodic EEG activity was found in 92% of the cases. Two patients had had neurological or ophthalmic surgery and 17% of our cases had undergone general surgery within 5 years prior to the clinical onset of CJD.

Amphotericin B delays the incubation period of scrapie in intracerebrally inoculated hamsters

The scrapie-infected hamster has been considered an excellent model for the study of slow virus diseases of man (Creutzfeldt-Jakob disease) and animals. At the moment no therapy is available for the cure of these fatal central nervous system diseases, although several drugs have been tested. We found that amphotericin B (AmB), a polyene antibiotic, increased the incubation time of scrapie disease in animals infected by either the intraperitoneal or intracerebral route. Hamsters inoculated with a 10% brain suspension of the 263K strain of scrapie showed clinical signs of disease in 54.6 +/- 4.7 days. Under AmB treatment (1 mg/kg for 6 days a week) the incubation time increased with the length of treatment, up to a maximum delay of 45 days. AmB may interact with the scrapie agent on cell plasma membranes and may thereby decrease the rate of scrapie replication. However, AmB did not have any effect when administered after the clinical onset of scrapie disease.

Molecular forms of cholinesterases in CSF of Alzheimer's disease/senile dementia of Alzheimer type patients and matched neurological controls

Acetylcholinesterase, pseudocholinesterase and their molecular forms were measured in the CSF of patients affected by Alzheimer's disease and of matched neurological controls. Three different molecular forms of ChE were found in the CSF of both groups of patients, but only two of them belonged to 'true' AChE. No differences were found between Alzheimer's disease patients and neurological controls in all the examined parameters.

Dementia in Parkinson's disease: possible specific involvement of the frontal lobes

We carried out a neuropsychological study on cognitive impairment in 57 subjects affected by idiopathic Parkinson's Disease (PD) and 32 subjects affected by Alzheimer's Disease (AD). First, we found two different subgroups of Parkinsonian patients, the first one with and the second without dementia. We clearly identified these two distinct subclinical entities regardless of mean age, age of onset, duration of treatment; on the contrary, the type of treatment seems to play a specific role in the appearance of dementia in PD, anticholinergics being assumed almost exclusively by demented Parkinsonian patients. Second, we observed two main differences for cognitive impairment between PD with dementia and AD. In fact, cognitive impairment is consistently more evident in Alzheimer patients than in Parkinsonian ones with dementia; in addition, demented Parkinsonians show a pattern of impairment similar to that exhibited by patients affected by frontal lobe lesions. This result supports neuroanatomical and neurochemical data on the involvement of the whole dopaminergic system in PD and the role played by the ventromedial tegmental area projecting to the frontal cortex in causing cognitive dysfunction in this disease.

Isonicotinic hydrazide causes seizures in scrapie-infected hamsters with shorter latency than in control animals: a possible GABAergic defect

Isonicotinic hydrazide, a drug that decreases the level of GABA, when injected subcutaneously in control and scrapie-infected hamsters induced tonic-clonic seizures in scrapie hamsters significantly earlier (P less than 0.0001) than in control animals. This suggests depression of the GABAergic system in scrapie-infected hamsters. To determine whether this lesion is pre or postsynaptic we measured the level of GABA, glutamate, cGMP and cAMP and the GABA-benzodiazepine receptor complex.

Choline acetyltransferase activity and [3H]quinuclidinylbenzilate binding in brains of scrapie-infected hamsters

Choline acetyltransferase (ChAT) activity and [3H]quinuclidinylbenzilate binding were studied in the brain of scrapie-infected hamsters and sham inoculated controls. Although scrapie-infected hamsters showed no reduction of ChAT activity compared to the controls, they showed a decrease in the affinity and maximum number of post-synaptic muscarinic receptors. Scrapie virus thus alters the cholinergic system at the post-synaptic rather than at the pre-synaptic level.

Acute administration of individual optimal dose of physostigmine fails to improve mnesic performances in Alzheimers Presenile Dementia

Eight patients affected by Alzheimer's Presenile Dementia (AD) received acute administration of physostigmine individual optimal dose per os (n = 4) or subcutaneously (n = 4). The individual physostigmine dose was assessed by means of serum cholinesterase activity monitoring. The possible beneficial effects after treatment were evaluated by using two memory tests: Reys' 15 words and Digit Span from Wechsler memory scale. Although a slight behavioral activation was noted in all patients after treatment, the comparison between mean scores obtained by AD patients in mnesic tests before and after the acute physostigmine administration, with either therapeutic modality, failed to reach the level of statistical significance. Some implications of these disappointing results are briefly discussed.

Peripheral neuropathy in the course of progressive systemic sclerosis: light and ultrastructural study

We present the case of a woman with progressive systemic sclerosis (PSS) in whom the usual symptoms were preceded by a rapidly progressive peripheral neuropathy. Few cases of peripheral nerve involvement have been described. For the first time we report an ultrastructural study of an affected peripheral nerve and muscle. In the sural nerve we found an almost complete loss of myelinated fibers. Schwann cells showed an abnormal hyperplasia of their basal membranes and structural signs of denervation. Spindle-shaped banded structures were seen in the cytoplasm of Schwann cells and in the endoneurium. On the basis of these ultrastructural data some hypotheses on the pathogenetic mechanism of this neuropathy are discussed.

Oral administration of chronic physostigmine does not improve cognitive or mnesic performances in Alzheimer's presenile dementia

Physostigmine was administered orally 1 mg q.i.d. for one month to 8 patients with a clinical diagnosis of Alzheimer's presenile dementia. The possible beneficial effects of the drug were evaluated by means of a neuropsychological battery administered to all patients before and after treatment. The performances obtained by demented patients on retest did not show any difference in comparison with performances obtained on the first neuropsychologic assessment. Some implications of these negative results are briefly discussed.

Neurophysiological study of normal pressure hydrocephalus

A neuropsychological Mental Deterioration Battery (MDB) was used to identify deterioration profiles of 43 patients afflicted with normal pressure hydrocephalus (NPH) (n = 18) or other forms of dementia (n = 25). The NPH patients submitted to a shunt-intervention (n = 10) were also evaluated after surgery. A comparison of profiles, obtained from the experimental and control groups, shows that NPH patients seem to be more impaired in tests designed to detect frontal lobe involvement. Some implications of the relatively greater impairment of frontal functions in NPH dementia are discussed.

Influence of age, sex, literacy and pathologic lesion on incidence, severity and type of aphasia

The influence of sex, age, educational level and pathologic lesion on incidence, severity and clinical form of aphasia was investigated in 390 right-handed, left brain-damaged patients. Sex and educational level were not related to any parameter. Etiology of lesion and age were related to both incidence and type of aphasia. Incidence of aphasia increased with age and was higher in patients with cerebrovascular accidents than in subjects with other types of brain lesions. Non-fluent forms of aphasia were more frequent in young patients suffering from acute cerebrovascular accidents, whereas anomia prevailed in neoplastic subjects and Wernicke's aphasia increased regularly in frequency with age. Some tentative explanations of these findings are discussed.

The relationship between type of naming error and semantic-lexical discrimination in aphasic patients

When submitted to confrontation naming tasks, aphasic patients show different types of naming errors: phonetic, phonemic and verbal-semantic paraphasias, neologisms and anomia, but it is generally difficult to decide whether these errors are mainly due to a breakdown of the semantic systems or to post-lexical phonological disorders. In order to clarify this issue, 118 aphasic patients were given 3 tests of confrontation naming and 3 tests of semantic-lexical discrimination. Naming errors on confrontation were used to classify aphasic patients in various subgroups (according to the prevalence of a given type of naming error), whereas performances obtained on tests of semantic-lexical discrimination were taken as an index of disorganization of the semantic systems. The performances on semantic discrimination tests of patients showing a prevalence of phonetic, phonemic and verbal-semantic paraphasias, neologisms and anomia on confrontation naming tasks were compared. A very small number of semantic discrimination errors was obtained by patients showing a prevalence of phonetic and phonemic transformations on confrontation, whereas a much larger number of semantic discrimination errors was obtained by patients showing a prevalence of verbal-semantic paraphasias, neologisms and anomia.

Cognitive impairment and chronic alcohol abuse: a neuropsychological study

Twenty-eight chronic alcoholic subjects were submitted to our Mental Deterioration Battery. The scores obtained by this group, corrected for age and educational level, were compared with those achieved by a control group. Our data do not confirm a selective impairment of the functions related to the right hemisphere; they show a diffuse cerebral damage and suggest, perhaps, a major impairment of the verbal functions subserved by the left hemisphere. Therefore, according to our data the question of selective hemispheric impairment as opposed to more diffuse cerebral damage in chronic alcoholism still remains open.

Neuropsychological correlates of localized cerebral lesions in non-aphasic brain-damaged patients

A neuropsychological test battery made up of verbal, visual-spatial, and intelligence tests was administered to 82 right and 67 on-aphasic left brain-damaged patients with localized cerebral lesions, in order to draw impairment profiles of the various subgroups. Separate analyses were undertaken on patients with unilobar and multilobar lesions. As for hemisphere effects, LH patients performed worse than RH subjects on verbal tests, while the reverse was true for visual-spatial tasks. As for lobe effects, patients with frontal lobe damage fared worse than other subgroups on word fluency, independent of the side of the lesion. RH patients with multilobar posterior lesions were significantly more impaired than other RH subgroups on the test of Copying Drawings with Landmarks, probably owing to the detrimental effect of unilateral spatial neglect on tasks requiring an accurate visual-spatial analysis.