Evaluation of CSF1R-related adult onset leukoencephalopathy with axonal spheroids and pigmented glia diagnostic criteria.

BACKGROUND AND PURPOSE: Diagnostic criteria for adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) due to colony-stimulating factor 1 receptor (CSF1R) mutation have recently been proposed. Our objective was to assess their accuracy in an independent multicenter cohort. METHODS: We evaluated the sensitivity and specificity of the diagnostic criteria for ALSP (including the "probable" and "possible" definitions) in a national cohort of 22 patients with CSF1R mutation, and 59 patients with an alternative diagnosis of adult onset inherited leukoencephalopathy. RESULTS: Overall, the sensitivity of the diagnostic criteria for ALSP was 82%, including nine of 22 patients diagnosed as probable and nine of 22 diagnosed as possible. Twenty of the 59 CSF1R mutation-negative leukoencephalopathies fulfilled the diagnostic criteria, leading to a specificity of 66%. CONCLUSIONS: Diagnostic criteria for ALSP have an overall limited sensitivity along with a modest specificity. We suggest that in patients suspected of genetic leukoencephalopathy, a comprehensive magnetic resonance imaging pattern-based approach is warranted, together with white matter gene panel or whole exome sequencing.

Working memory performance is related to intrinsic resting state functional connectivity changes in community-dwelling elderly cohort.

Characterization of normal age-related changes in resting state brain networks associated with working memory performance is a major prerequisite for studying neurodegenerative diseases. The aim of this study was to investigate the relationship between performing a working memory task (under MRI) and resting-state brain networks in a large cohort of healthy elderly subjects (n=337). Functional connectivity and interactions between networks were assessed within the default mode (DMN), salience (SN), and right and left central executive (CEN) networks in two groups of subjects classed by their performance (low and high). The low performance group showed lower functional connectivity in both the DMN and SN, and higher functional connectivity in the right and left CEN compared to the high performance group. Overall the functional connectivity within the DMN and the CEN were correlated. The lower functional connectivity within the DMN and SN in the low performance group is suggestive of altered attentional and memory processes and/or altered motivation. The higher functional connectivity within the CEN could be related to compensatory mechanisms, without which the subjects would have even lower performances. The correlation between the DMN and CEN suggests a modulation between the lower functional connectivity within the DMN and the higher functional connectivity within the CEN when performance is reduced. Finally, this study suggests that performance modifications in healthy elderly subjects are associated with reorganization of functional connectivity within the DMN, SN, and CEN.

Working memory activation of neural networks in the elderly as a function of information processing phase and task complexity.

Changes in working memory are sensitive indicators of both normal and pathological brain aging and associated disability. The present study aims to further understanding of working memory in normal aging using a large cohort of healthy elderly in order to examine three separate phases of information processing in relation to changes in task load activation. Using covariance analysis, increasing and decreasing neural activation was observed on fMRI in response to a delayed item recognition task in 337 cognitively healthy elderly persons as part of the CRESCENDO (Cognitive REServe and Clinical ENDOphenotypes) study. During three phases of the task (stimulation, retention, probe), increased activation was observed with increasing task load in bilateral regions of the prefrontal cortex, parietal lobule, cingulate gyrus, insula and in deep gray matter nuclei, suggesting an involvement of central executive and salience networks. Decreased activation associated with increasing task load was observed during the stimulation phase, in bilateral temporal cortex, parietal lobule, cingulate gyrus and prefrontal cortex. This spatial distribution of decreased activation is suggestive of the default mode network. These findings support the hypothesis of an increased activation in salience and central executive networks and a decreased activation in default mode network concomitant to increasing task load.

Education modulates the impact of white matter lesions on the risk of mild cognitive impairment and dementia.

OBJECTIVES: Conflicting results have been reported regarding the association between white matter lesions (WML) and cognitive impairment. We hypothesized that education, a marker of cognitive reserve (CR), could modulate the effects of WML on the risk of mild cognitive impairment (MCI) or dementia. METHODS: We followed 500 healthy subjects from a cohort of community-dwelling persons aged 65 years and over (ESPRIT Project). At baseline, WML volume was measured using a semi-automatic method on T2-weighted MRI. Standardized cognitive and neurological evaluations were repeated after 2, 4, and 7 years. The sample was dichotomized according to education level into low (≤8 years) and high (>8 years) education groups. Cox proportional hazard models were constructed to study the association between WML and risk of MCI/dementia. RESULTS: The interaction between education level and WML volume reached significance (p = 0.017). After adjustment for potential confounders, the association between severe WML and increased MCI/dementia risk was significant in the low education group (≤8 years) (p = 0.02, hazard ratio [HR]: 3.77 [1.29-10.99]), but not in the high education group (>8 years) (p = 0.82, HR: 1.07 [0.61-1.87]). CONCLUSIONS: Severe WML significantly increases the risk of developing MCI/dementia over a 7-year period in low educated participants. Subjects with higher education levels were seen to be more likely to be resilient to the deleterious effects of severe WML. The CR hypothesis suggests several avenues for dementia prevention.

APOE ε4 and risk for Alzheimer's disease: do regionally distributed white matter hyperintensities play a role?

BACKGROUND: We previously demonstrated that parietal lobe white matter hyperintensities (WMH) increase the risk for Alzheimer's disease (AD). Here, we examined whether individuals with apolipoprotein E gene (APOE ε4) have increased parietal WMH volume. METHODS: Participants were from the Washington Heights-Inwood Columbia Aging Project (WHICAP; n = 694, 47 with dementia) in northern Manhattan and the Etude Santé Psychologique Prévalence Risques et Traitement study (ESPRIT; n = 539, 8 with dementia) in Montpellier. The association between regional WMH and APOE ε4 was examined separately in each group and then in a combined analysis. RESULTS: In WHICAP, ε4 carriers had higher WMH volume particularly in parietal and occipital lobes. In ESPRIT, ε4 carriers had elevated WMH particularly in parietal and temporal lobes. In the combined analysis, ε4 carriers had higher WMH in parietal and occipital lobes. Increased WMH volume was associated with increased frequency of dementia irrespective of APOE ε4 status; those with the ε4 were more likely to have dementia if they also had increased parietal WMH. CONCLUSIONS: APOE ε4 is associated with increased parietal lobe WMH.

Muscle strength, quantity and quality and muscle fat quantity and their association with oxidative stress in patients with facioscapulohumeral muscular dystrophy: Effect of antioxidant supplementation.

The purpose of this study was to identify causes of quadriceps muscle weakness in facioscapulohumeral muscular dystrophy (FSHD). To this aim, we evaluated quadriceps muscle and fat volumes by magnetic resonance imaging and their relationships with muscle strength and oxidative stress markers in adult patients with FSHD (n = 32) and healthy controls (n = 7), and the effect of antioxidant supplementation in 20 of the 32 patients with FSHD (n = 10 supplementation and n = 10 placebo) (NCT01596803). Compared with healthy controls, the dominant quadriceps strength and quality (muscle strength per unit of muscle volume) were decreased in patients with FSHD. In addition, fat volume was increased, without changes in total muscle volume. Moreover, in patients with FSHD, the lower strength of the non-dominant quadriceps was associated with lower muscle quality compared with the dominant muscle. Antioxidant supplementation significantly changed muscle and fat volumes in the non-dominant quadriceps, and muscle quality in the dominant quadriceps. This was associated with improved muscle strength (both quadriceps) and antioxidant response. These findings suggest that quadriceps muscle strength decline may not be simply explained by atrophy and may be influenced also by the muscle intrinsic characteristics. As FSHD is associated with increased oxidative stress, supplementation might reduce oxidative stress and increase antioxidant defenses, promoting changes in muscle function.

Genome-wide association study confirms BST1 and suggests a locus on 12q24 as the risk loci for Parkinson's disease in the European population.

We performed a three-stage genome-wide association study (GWAS) to identify common Parkinson's disease (PD) risk variants in the European population. The initial genome-wide scan was conducted in a French sample of 1039 cases and 1984 controls, using almost 500 000 single nucleotide polymorphisms (SNPs). Two SNPs at SNCA were found to be associated with PD at the genome-wide significance level (P < 3 × 10(-8)). An additional set of promising and new association signals was identified and submitted for immediate replication in two independent case-control studies of subjects of European descent. We first carried out an in silico replication study using GWAS data from the WTCCC2 PD study sample (1705 cases, 5200 WTCCC controls). Nominally replicated SNPs were further genotyped in a third sample of 1527 cases and 1864 controls from France and Australia. We found converging evidence of association with PD on 12q24 (rs4964469, combined P = 2.4 × 10(-7)) and confirmed the association on 4p15/BST1 (rs4698412, combined P = 1.8 × 10(-6)), previously reported in Japanese data. The 12q24 locus includes RFX4, an isoform of which, named RFX4_v3, encodes brain-specific transcription factors that regulate many genes involved in brain morphogenesis and intracellular calcium homeostasis.

Cystatin C for kidney function assessment in patients with facioscapulohumeral muscular dystrophy.

BACKGROUND AND AIMS: Muscle mass (MM) impairment observed in facioscapulohumeral muscular dystrophy (FSHD) may bias estimated glomerular filtration rate (eGFR) based on creatinine (eGFRcreat). eGFR based on cystatin C (eGFRcys), produced by all nucleated cells, should be an interesting alternative. Main objectives were to compare eGFRcreat and eGRFcys for chronic kidney disease (CKD) staging and for annual eGFR evolution. Secondary objective was to analyse creatinine, cystatin C with measured MM. MATERIAL AND METHODS: During 4 years, 159 FSHD patients having one or more creatinine and cystatin C measurements (total samples: n = 379), with MM determination by bio-impedancemetry during their follow-up were included. eGFR were determined with CKD-Epi and EKFC equations. RESULTS: On first examination samples, mean eGFRcys was significantly lower than mean eGFRcreat of 25.5 and 17.9 ml/min/1.73 m2 using CKD-Epi and EKFC equations, respectively. 53.5% (CKD-Epi) and 59.1% (EKFC) of agreement were obtained when using eGFRcys instead of eGFRcreat with reclassifications occurring mainly towards more severe stages. Age was correlated with cystatin C but not with creatinine, MM was correlated with creatinine but not with cystatin C. eGFR decreases > 1 ml/min/1.73 m2 were more important when using eGFRcys instead of eGFRcreat (CKD-Epi: 37.5 vs 15.4%, p < 0.001; EKFC: 34.6 vs 20.2%, p < 0.01). CONCLUSION: Cystatin C which is independent of MM appears as a promising candidate biomarker for CKD diagnosis and follow-up in FSHD patient.

Metabolic syndrome and localization of white matter hyperintensities in the elderly population.

BACKGROUND: Metabolic syndrome (MetS) is defined as a clustering of metabolic disorders: abdominal obesity, dyslipidemia, hypertension, and hyperglycemia. Although specific components of MetS have been associated with white matter hyperintensities (WMH), less is known about the association between MetS as a whole and WMH, especially in normal aging. We aimed to: (1) investigate this association in a cohort of healthy elderly individuals, and (2) examine the relationship between MetS and the regional distribution of WMH, to further understanding of the relationship between MetS and structural brain changes. METHODS: Analyses were carried out on 308 participants (48.1% men, age: 71.0 ± 3.9 years) from the French longitudinal ESPRIT (Enquête de Santé Psychologique--Risques, Incidence et Traitement) study, who were free of cerebrovascular disease cognitive and functional impairment. Logistic regression models were used to examine the cross-sectional association between MetS (defined using the National Cholesterol Education Program-Adult Treatment Panel III criteria) and (1) WMH volumes, and (2) WMH volumes according to their localization in insulofrontal and temporoparietal regions. RESULTS: After adjusting for potential confounders, participants with MetS had a twofold increased chance of presenting with high levels of WMH volume compared with those without (odds ratio [OR] = 2.74, 95% confidence interval [CI]: 1.25-6.03). MetS was specifically associated with an increase of temporoparietal WMH volumes, but no association was found between MetS and WMH localized in the insulofrontal region. CONCLUSION: Our findings suggest that effective management of MetS may reduce WMH accumulation in brain areas already vulnerable to the aging process.

An international perspective on advanced neuroimaging: cometh the hour or ivory tower?

Over the past five to ten years, neuroimaging capability for neurodegenerative diseases has made remarkable progress. However, debate remains as to the true clinical utility of these advanced and costly investigations. Not only is the place of these tests in diagnostic algorithms unclear, but the access to them varies both within and between countries. We sought to gather informed opinion from recognized leaders in the field who can combine both an academic and a clinical perspective on the use of neuroimaging in their own countries. Opinion is presented from Scotland, Argentina, the Czech Republic, France, the USA and Australia. The emerging consensus was one of ongoing caution. While in most countries there was a sense that the use of more advanced imaging techniques was growing, their hour has not yet cometh. However, these techniques, rather than falling from the Ivory Tower, should descend slowly step by step onto fertile and receptive clinics from where better clinical guidelines will emerge.

Retrospective identification and characterization of mild cognitive impairment from a prospective population cohort.

OBJECTIVES: Mild cognitive impairment (MCI) case-finding criteria have low specificity in general population studies. This study retrospectively identifies cases of MCI and determines baseline criteria giving the highest discriminability. The ability of these criteria to increase current case detection specificity is estimated. DESIGN: A population-based cohort was recruited from electoral rolls from three French cities. Clinical and environmental characteristics were evaluated at baseline and at 2- and 4-year follow-up. The clinical characteristics of incident cases of dementia were examined retrospectively. PARTICIPANTS: Eight thousand nine hundred nineteen persons aged 65 years and older without dementia (60.8% women) were included in this study. The mean age (SD) of the participants was 74.2 (5.6) years for men and 74.4 (5.6) years for women. RESULTS: Three hundred twenty persons (3.6%) were retrospectively classified as MCI at baseline. This MCI group had poorer performance on all cognitive tests compared with the rest of the cohort, and a subsample undergoing MRI were found to have more white matter hyperintensities. The group were also characterized by the presence of an ApoE ε4 genotype (odds ratio [OR]: 2.17, confidence interval [CI]: 1.44-3.29 for men; OR: 2.27, CI: 1.59-3.24 for women) and instrumental activities of daily living loss (OR: 1.72, CI: 1.01-3.0 for men; OR: 1.49; CI: 0.97-2.3 for women). Women with MCI also had high depressive symptomatology (OR: 1.96; CI: 1.34-2.87), anticholinergic drug use (OR: 1.59; CI: 1.05-2.28), and low body mass index (OR: 1.54, CI: 1.05-2.28) and for men a history of stroke (OR: 2.17, CI: 1.16-4.05) and glycemia (OR: 1.72, CI: 1.13-2.71). Addition of these characteristics to conventional MCI definitions increases their specificity. CONCLUSIONS: This general population study using a retrospective method for classifying persons with MCI identified gender-specific noncognitive clinical variables that may increase specificity.

Neurological signs and late-life depressive symptoms in a community population: the ESPRIT study.

OBJECTIVE: Depression in the elderly is common and often resistant to treatment. It has been suggested that late-life depression may be related to underlying neurobiological changes. However, these observations are derived from diverse clinical samples and as yet have not been confirmed in a more representative population study. Our aim was to investigate associations between neurological signs as markers of underlying brain dysfunction and caseness for depression in an elderly community sample, controlling for physical health and comorbid/past neurological disorders. METHOD: A cross-sectional analysis of 2102 older people without dementia from the ESPRIT project. Depressive symptomatology was ascertained using the CES-D and abnormal neurological signs/comorbidity from a full neurological examination according to ICD-10 criteria. RESULTS: Pyramidal, extrapyramidal, cranial nerve and sensory deficit signs were significantly associated with case-level depressive symptoms. However, all odds ratios were close to null values in participants who did not have previous neurological disorder. CONCLUSIONS: We confirmed previous findings of an association between neurological signs and case-level depressive symptoms in late life. However, this association may simply reflect the impact of more severe comorbid neurological disorder.

Olive oil and cognition: results from the three-city study.

BACKGROUND: Olive oil is a major component of the Mediterranean diet suggested to be beneficial to counteract Alzheimer's disease. AIM OF THE STUDY: Our objective was to examine the association between olive oil use, cognitive deficit and cognitive decline in a large elderly population. METHODS: We followed 6,947 subjects with a brief baseline food frequency questionnaire and repeated cognitive tests. Olive oil intake was categorized as none (22.7%), moderate (use for cooking or dressing, 39.9%) and intensive (use for both cooking and dressing, 37.4%). Associations between olive oil and cognitive outcomes were examined taking into account socio-economic factors, health behaviors, health measures and other dietary intakes. RESULTS: Participants with moderate or intensive use of olive oil compared to those who never used olive oil showed lower odds of cognitive deficit for verbal fluency and visual memory. For cognitive decline during the 4-year follow-up, the association with intensive use was significant for visual memory (adjusted OR = 0.83, 95% CI: 0.69-0.99) but not for verbal fluency (OR = 0.85, 95% CI: 0.70-1.03) in multivariate analysis. CONCLUSIONS: This olive oil-cognition association needs to be confirmed by further studies. However, our findings already shed light on the potential importance of olive oil in the Mediterranean diet and on its beneficial effects on health.

Adherence to a Mediterranean diet, cognitive decline, and risk of dementia.

CONTEXT: Higher adherence to a Mediterranean-type diet is linked to lower risk for mortality and chronic diseases, but its association with cognitive decline is unclear. OBJECTIVE: To investigate the association of a Mediterranean diet with change in cognitive performance and risk for dementia in elderly French persons. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort study of 1410 adults (> or = 65 years) from Bordeaux, France, included in the Three-City cohort in 2001-2002 and reexamined at least once over 5 years. Adherence to a Mediterranean diet (scored as 0 to 9) was computed from a food frequency questionnaire and 24-hour recall. MAIN OUTCOME MEASURES: Cognitive performance was assessed on 4 neuropsychological tests: the Mini-Mental State Examination (MMSE), Isaacs Set Test (IST), Benton Visual Retention Test (BVRT), and Free and Cued Selective Reminding Test (FCSRT). Incident cases of dementia (n = 99) were validated by an independent expert committee of neurologists. RESULTS: Adjusting for age, sex, education, marital status, energy intake, physical activity, depressive symptomatology, taking 5 medications/d or more, apolipoprotein E genotype, cardiovascular risk factors, and stroke, higher Mediterranean diet score was associated with fewer MMSE errors (beta = -0.006; 95% confidence interval [CI], -0.01 to -0.0003; P = .04 for 1 point of the Mediterranean diet score). Performance on the IST, BVRT, or FCSRT over time was not significantly associated with Mediterranean diet adherence. Greater adherence as a categorical variable (score 6-9) was not significantly associated with fewer MMSE errors and better FCSRT scores in the entire cohort, but among individuals who remained free from dementia over 5 years, the association for the highest compared with the lowest group was significant (adjusted for all factors, for MMSE: beta = -0.03; 95% CI, -0.05 to -0.001; P = .04; for FCSRT: beta = 0.21; 95% CI, 0.008 to 0.41; P =.04). Mediterranean diet adherence was not associated with the risk for incident dementia (fully adjusted model: hazard ratio, 1.12; 95% CI, 0.60 to 2.10; P = .72), although power to detect a difference was limited. CONCLUSIONS: Higher adherence to a Mediterranean diet was associated with slower MMSE cognitive decline but not consistently with other cognitive tests. Higher adherence was not associated with risk for incident dementia.

Frailty among community-dwelling elderly people in France: the three-city study.

BACKGROUND: To better understand the contribution of frailty to health-related outcomes in elderly persons, it seems valuable to explore data from cohort studies across the world in an attempt to establish a comprehensive definition. The purpose of this report is to show the characteristics of frailty and observe its prognosis in a large sample of French community-dwelling elderly persons. METHODS: We used data from 6078 persons 65 years old or older participating in the Three-City Study (3C). Frailty was defined as having at least three of the following criteria: weight loss, weakness, exhaustion, slowness, and low activity. Principal outcomes were incident disability, hospitalization, and death. Multiple covariates were used to test the predictive validity of frailty on these outcomes. RESULTS: Four hundred twenty-six individuals (7%) met frailty criteria. Participants classified as frail were significantly older, more likely to be female, and less educated and reported more chronic diseases, lower income, and poorer self-reported health status in comparison to nonfrail participants. In multivariate analysis, frailty was significantly associated with 4-year incidence of disability in activities of daily living (ADL) and instrumental ADL. However, frailty was marginally associated with incident hospitalization and was not a statistically significant predictor of incident mobility disability or mortality adjusting for potential confounding factors. CONCLUSIONS: Frailty is not specific to a subgroup or region of the world. The construct proposed by Fried and colleagues confirms its predictive validity for adverse-health outcomes, particularly for certain components of disability, thus suggesting that it may be useful in population screening and predicting service needs.

Brain SPECT in subtypes of mild cognitive impairment. Findings from the DESCRIPA multicenter study.

The Development of Screening Guidelines and Clinical Criteria of Predementia Alzheimer's Disease (DESCRIPA) multicenter study enrolled patients with MCI or subjective cognitive complaints (SUBJ), a part of whom underwent optional brain perfusion SPECT. These patients were classified as SUBJ (n = 23), nonamnestic MCI (naMCI; n = 17) and amnestic MCI (aMCI; n = 40) based on neuropsychology. Twenty healthy subjects formed the control (CTR) group. Volumetric regions of interest (VROI) analysis was performed in six associative cortical areas in each hemisphere. ANOVA for repeated measures, corrected for age and center, showed significant differences between groups (p = 0.01) and VROI (p < 0.0001) with a significant group-region interaction (p = 0.029). In the post hoc comparison, SUBJ did not differ from CTR. aMCI disclosed reduced uptake in the left hippocampus and bilateral temporal cortex (compared with CTR) or in the left hippocampus and bilateral parietal cortex (compared with SUBJ). In the naMCI group, reduced VROI values were found in the bilateral temporal cortex and right frontal cortex. In the comparison between aMCI and naMCI, the former had lower values in the left parietal cortex and precuneus. Discriminant analysis between SUBJ/CTR versus all MCI patients allowed correct allocations in 73 % of cases. Mean VROI values were highly correlated (p < 0.0001) with the learning measure of a verbal memory test, especially in the bilateral precunei and parietal cortex and in the left hippocampus. In a subset of 70 patients, mean VROI values showed a significant correlation (p < 0.05) with the white matter hyperintensities score on MRI. In conclusion, MCI subtypes have different perfusion patterns. The aMCI group exhibited a pattern that is typical of early Alzheimer's disease, while the naMCI group showed a more anterior pattern of hypoperfusion. Instead, a homogeneous group effect was lacking in SUBJ.

Primary and secondary care consultations in elderly demented individuals in France. Results from the Three-City Study.

BACKGROUND/AIMS: Our purpose was to analyze consultations with primary- and secondary-care physicians by demented people and identify factors that hamper or facilitate consultation. METHODS: In total, 498 demented subjects were evaluated within the Three-City Study, a population-based cohort of individuals aged >or=65 years.Primary- and secondary-care consultations (consultation with a specialist and/or treatment with anti-dementia drugs) were assessed by a neurologist or geriatrician. RESULTS: Thirty-five percent of the demented subjects did not seek advice for their cognitive problems and only 31% consulted a specialist. Consultation for primary care was principally dependent on the subjects' own awareness of the cognitive disorder and on their age. Factors associated with consultation for secondary care were younger age, higher education level, higher instrumental activities of daily living disability and awareness of the cognitive disorder by the subject, all of which predicted more frequent consultation. The level of cognitive performance had only a slight influence on primary care and none on secondary care. CONCLUSION: The failure to see a physician due to dementia, especially secondary-care practitioners, is frequent in the community, particularly in the oldest subjects.

Leisure activity and cognitive decline in incident Alzheimer disease.

BACKGROUND: High rates of leisure activity have been associated with reduced risk of Alzheimer disease (AD). OBJECTIVE: To determine whether prediagnosis leisure activity modifies the rate of cognitive decline in patients with AD. DESIGN: Inception cohort followed up longitudinally for a mean of 5.3 years (up to 13.9 years). SETTING: Urban community. PARTICIPANTS: A total of 283 patients with incident AD (mean age, 79 years; 56.2% Hispanic and 31.1% African American). MAIN OUTCOME MEASURES: Change in a composite cognitive score from diagnosis on and during the entire study follow-up. RESULTS: In multivariate-adjusted generalized estimating equation models of postdiagnosis change (n = 133), each leisure activity was associated with an additional yearly decline of 0.005 of a z-score unit in cognitive score (P = .17). In models expanded to include cognitive change during study follow-up, including evaluations before and after diagnosis (n = 283), each activity was associated with an additional yearly decline of 0.005 of a z-score unit in cognitive score (P = .03). The association was strongest for intellectual activities. CONCLUSIONS: Greater participation in prediagnosis leisure activities, especially intellectual activities, was associated with faster cognitive decline, supporting the hypothesis that the disease course in AD may vary as a function of cognitive reserve.

Diagnostic value of event-related evoked potentials N200 and P300 subcomponents in early diagnosis of Alzheimer's disease and mild cognitive impairment.

Event-related potentials (ERPs) have a large application in the evaluation of cognitive processes, particularly in Alzheimer's disease (AD). The aim of the present study was to evaluate the clinical relevance of event-related evoked potentials (N2 and P3 subcomponents) in early diagnosis of AD and mild cognitive impairment (MCI). We prospectively studied 60 subjects. They all underwent the following investigations: neurologic and neuropsychological examination; functional evaluation, i.e., ERPs; cerebral imagery (morphologic and functional). Subjects were classified into 3 groups: group 1: 30 dementia of Alzheimer type (NINCDS-ADRDA, DSM-IV criteria); group 2: 20 MCI; and group 3: 10 control subjects. ERPs were significantly different between the groups (AD, MCI, control subjects), with a marked increase of P3 latencies, particularly when compared with N2 latencies (P < 0.0001). Furthermore, sensitivity was 87% to 95% for the differentiation of AD patients from MCI and control subjects, using prolonged P3 latencies (specificity, 90% to 95%), whereas using N2 prolonged latencies, sensitivity was 70% to 75% (specificity, 70% to 90%). Moreover, in the MCI group, N2 latencies strongly discriminated MCI from control subjects, with 90% sensitivity and 70% specificity and correctly categorized 80% of MCI subjects against 73% for P3. The abnormalities of N2 and P3 components may be linked, in AD and MCI, to an alteration of automatic and controlled attention processing.

[Mild cognitive impairment]. / Mild cognitive impairment.

The concept of mild cognitive impairment (MCI) was proposed by Petersen et al. (1997, 1999) as a nosologic entity referring to elderly persons with mild cognitive deficit and without dementia. MCI is widely used in studies as an intermediate stage between cognitive normalcy and dementia. MCI now appears, however, to be a heterogeneous clinical entity. The many sources of heterogeneity that have been pointed out include: heterogeneity in etiological factors (various types of degenerative lesions, vascular risk factors, psychiatric features, concomitant non-neurological diseases), in clinical symptoms, and in clinical course (with decline, stable, or reversible cognitive impairment). New clinical criteria have thus been proposed for use in research and in clinical practice: 1) cognitive complaint from the patient, family, or both, 2) report by the subject or reporter of a decline in cognitive or functional performance, relative to previous abilities, 3) cognitive disorders evidenced by clinical evaluation: impairment in memory or another cognitive domain, 4) cognitive impairment without any repercussions on daily life, even if the subject reports difficulties concerning complex daily activities, and 5) no dementia. Those new criteria, essentially clinical, may be better adapted to both clinical research and daily clinical practice. Biological and radiological markers will provide greater and more systematic support for diagnosis in the near future, particularly for early detection of Alzheimer's disease.