Upregulation of select rab GTPases in cholinergic basal forebrain neurons in mild cognitive impairment and Alzheimer's disease

Endocytic system dysfunction is one of the earliest disturbances that occur in Alzheimer's disease (AD), and may underlie the selective vulnerability of cholinergic basal forebrain (CBF) neurons during the progression of dementia. Herein we report that genes regulating early and late endosomes are selectively upregulated within CBF neurons in mild cognitive impairment (MCI) and AD. Specifically, upregulation of rab4, rab5, rab7, and rab27 was observed in CBF neurons microdissected from postmortem brains of individuals with MCI and AD compared to age-matched control subjects with no cognitive impairment (NCI). Upregulated expression of rab4, rab5, rab7, and rab27 correlated with antemortem measures of cognitive decline in individuals with MCI and AD. qPCR validated upregulation of these select rab GTPases within microdissected samples of the basal forebrain. Moreover, quantitative immunoblot analysis demonstrated upregulation of rab5 protein expression in the basal forebrain of subjects with MCI and AD. The elevation of rab4, rab5, and rab7 expression is consistent with our recent observations in CA1 pyramidal neurons in MCI and AD. These findings provide further support that endosomal pathology accelerates endocytosis and endosome recycling, which may promote aberrant endosomal signaling and neurodegeneration throughout the progression of AD.     

Hippocampal neurons in pre-clinical Alzheimer's disease

In a previous study of hippocampal neurons in aging and AD [Lancet 344 (1994) 769], we demonstrated that the loss of neurons in the CA1 region was disease-specific and not related to aging. In the present study, we examined for loss of hippocampal neurons in preclinical AD, a period during which there are abundant amyloid deposits in the brain but no evidence of cognitive decline. We examined the postmortem brains of 33 subjects from the Baltimore Longitudinal Study of Aging and the Johns Hopkins Alzheimer's Disease Research Center. Using unbiased stereology, we estimated the total number of neurons in the granule cell layer, hilus, CA3-2, CA1, and subiculum of AD (n = 14) preclinical AD (n = 8), and age-matched control subjects (n = 11). The results from the present study confirm our previous finding of significant neuronal losses in the CA1 (48%), hilus (14%), and subiculum (24%) in AD [Lancet 344 (1994) 769]. However, we did not observe a significant loss of neurons in CA1 or any of the other subdivisions of the hippocampus in preclinical AD.     

Subregional hippocampal atrophy predicts Alzheimer's dementia in the cognitively normal

Atrophic changes of the hippocampus are typically regarded as an early sign of Alzheimer's dementia (AD). Using the radial distance atrophy mapping approach, we compared the longitudinal MRI data of 10 cognitively normal elderly subjects who remained normal at 3-year and 6-year follow-up (NL-NL) and 7 cognitively normal elderly subjects who were diagnosed with mild cognitive impairment (MCI) 2.8 (range 2.0-3.9) and with AD 6.8 years (range 6.1-8.2) after baseline (NL-MCI(AD)). 3D statistical maps revealed greater hippocampal atrophy in the NL-MCI(AD) relative to the NL-NL group at baseline (left p=0.05; right p=0.06) corresponding to 10-15% CA1, and 10-25% subicular atrophy, and bilateral differences at 3-year follow-up (left p=0.001, right p<0.02) corresponding to 10-30% subicular, 10-20% CA1, and 10-20% newly developed CA2-3 atrophy. This preliminary study suggests that excess CA1 and subicular atrophy is present in cognitively normal individuals predestined to decline to amnestic MCI, while progressive involvement of the CA1 and subiculum, and atrophy spreading to the CA2-3 subfield in amnestic MCI, suggests future diagnosis of AD.     

Mild cognitive impairment as predictor for Alzheimer's disease in clinical practice: effect of age and diagnostic criteria

BACKGROUND: We investigated whether the predictive accuracy of mild cognitive impairment (MCI) for Alzheimer-type dementia (AD) in a clinical setting is dependent on age and the definition of MCI used. METHOD: Non-demented subjects older than 40 (n=320) who attended a memory clinic of a university hospital were reassessed 5 years later for the presence of AD. MCI was diagnosed according to the criteria of amnestic MCI, mild functional impairment (MFI), ageing-associated cognitive decline (AACD), and age-associated memory impairment (AAMI). The main outcome measure was the area under the curve (AUC) of a receiver operating characteristic (ROC) curve. Analyses were conducted on the entire sample and on subgroups of subjects aged 40-54, 55-69 and 70-85 years. RESULTS: A diagnosis of AD at follow-up was made in 58 subjects. Four of them were in the 40-54 age group, 29 in the 55-69 age group and 25 in the 70-85 age group. The diagnostic accuracy in the entire sample was low to moderately high with AUCs ranging from 0.56 (AACD) to 0.75 (amnestic MCI). A good predictive accuracy with an AUC >0.80 was only observed in subjects aged 70-85 using the criteria of amnestic MCI (AUC=0.84). CONCLUSIONS: The predictive accuracy of MCI for AD is dependent on age and the definition of MCI used. The predictive accuracy is good only for amnestic MCI in subjects 70-85 years. As subjects with prodromal AD are often younger than 70, the usefulness of MCI as predictor of AD in clinical practice is limited.     

APOE, ACT and CHRNA7 genes in the conversion from amnestic mild cognitive impairment to Alzheimer's disease

We have investigated whether the -86 C/T promoter polymorphism in CHRNA7 gene, the signal peptide polymorphism of the alpha1-antichymotripsin (ACT) gene or the APOE genotype are associated with an increased risk of mild cognitive impairment (MCI) or affect the risk of evolution to Alzheimer's disease (AD). We have followed up 89 patients with initial diagnoses of amnestic MCI for 49 months. Patients were separated into three groups: 27 subjects who remained with MCI, 40 that converted to AD before 20 months and 22 that converted to AD after. To assess the risk associated to each genotype a control group (n=90) without cognitive impairment was included. APOE4 allele was associated with an increased risk of MCI (OR: 6.04, 95% CI: 2.76-3.23; p<0.001) but did not have an effect on the probability of evolving AD. ACT or CHRNA7 genotypes were not associated with MCI but both appear to modify the risk of progression to dementia in opposing manners: ACT polymorphism increasing the risk to evolve to AD before 20 months (HR=2.03; 95% CI: 1-4.6; p=0.06) and CHRNA7 polymorphism protecting from evolution to dementia. Cox regression model demonstrated that ACT genotype confers a higher risk of rapid evolution to dementia than age or years of schooling. We conclude that APOE is a risk gene for amnestic MCI and that ACT and CHRNA7 may act in these patients as modifier genes for the time of progression to AD.     

Quantitative electroencephalography in mild cognitive impairment: longitudinal changes and possible prediction of Alzheimer's disease

The present study evaluated the clinical course of patients with mild cognitive impairment (MCI), the pattern of electroencephalography (EEG) changes following cognitive deterioration, as well as the potential of neurophysiological measures in predicting dementia. Twenty-seven subjects with MCI were followed for a mean follow up period of 21 months. Fourteen subjects (52%) progressed (P MCI) to clinically manifest Alzheimer's disease (AD), and 13 (48%) remained stable (S MCI). The two MCI subgroups did not differ in baseline EEG measures between each other and the healthy controls (n = 16), but had significantly lower theta relative power at left temporal, temporo-occipital, centro-parietal, and right temporo-occipital derivation when compared to the reference AD group (n = 15). The P MCI baseline alpha band temporo-parietal coherence, alpha relative power values at left temporal and temporo-occipital derivations, theta relative power values at frontal derivations, and the mean frequency at centro-parietal and temporo-occipital derivations overlapped with those for AD and control groups. After the follow-up, the P MCI patients had significantly higher theta relative power and lower beta relative power and mean frequency at the temporal and temporo-occipital derivations. A logistic regression model of baseline EEG values adjusted for baseline Mini-Mental Test Examination showed that the important predictors were alpha and theta relative power and mean frequency from left temporo-occipital derivation (T5-O1), which classified 85% of MCI subjects correctly.     

Changes of some oxidative stress markers in the serum of patients with mild cognitive impairment and Alzheimer's disease

Mild cognitive impairment (MCI) is a nosological entity proposed as an intermediate state between normal aging and dementia. MCI seems to represent an early stage of Alzheimer's disease (AD) and there is a great interest in the relationship between MCI and the progression to AD. Some studies have demonstrated an accumulation of products of free radical damage in the central nervous system and in the peripheral tissues of subjects with AD or mild cognitive impairment. The aim of the present work was to evaluate the serum levels of some enzymatic antioxidant defences like superoxide dismutase (SOD) and glutathione peroxidase (GPX), as well as lipid peroxidation markers like MDA (malondialdehyde), in MCI and AD patients, compared with age-matched healthy controls. The subjects of this study (45 patients) consisted of 15 individuals with mild cognitive impairment (MCI), 15 with Alzheimer's disease (AD) and 15 healthy age-matched controls. Biochemical analyses showed a similar decrease of the main enzymatic antioxidant defences (SOD and GPX) and increased production of lipid peroxidation marker (MDA) in the serum of the MCI and AD patients, compared to age-matched control group. This study clearly demonstrates that oxidative stress damage occurs in patients with MCI and AD. Moreover, some enzymatic markers of oxidative stress are similar in MCI and AD patients, suggesting that oxidative damage could be one important aspect for the onset of AD.     

Effects of ApoE4 and maternal history of dementia on hippocampal atrophy

We applied an automated hippocampal segmentation technique based on adaptive boosting (AdaBoost) to the 1.5 T magnetic resonance imaging (MRI) baseline and 1-year follow-up data of 243 subjects with mild cognitive impairment (MCI), 96 with Alzheimer's disease (AD), and 145 normal controls (NC) scanned as part of the Alzheimer's Disease Neuroimaging Initiative (ADNI). MCI subjects with positive maternal history of dementia had smaller hippocampal volumes at baseline and at follow-up, and greater 12-month atrophy rates than subjects with negative maternal history. Three-dimensional maps and volumetric multiple regression analyses demonstrated a significant effect of positive maternal history of dementia on hippocampal atrophy in MCI and AD after controlling for age, ApoE4 genotype, and paternal history of dementia, respectively. ApoE4 showed an independent effect on hippocampal atrophy in MCI and AD and in the pooled sample.     

CSF cortisol in Alzheimer's disease and mild cognitive impairment

Hypercortisolaemia occurs in Alzheimer's disease (AD) and may be involved in the AD related neurodegenerative process. In order to determine whether brain structures are exposed to high cortisol concentrations early in AD, we measured cerebrospinal fluid (CSF) cortisol in 66 subjects with AD, 33 subjects with mild cognitive impairment (MCI) and 34 control subjects. CSF cortisol concentrations were higher in AD subjects compared to controls (p<0.001) and to MCI subjects (p=0.002). There was no significant increase of cortisol in MCI subjects compared with controls suggesting that the increase of CSF cortisol is not an early event in the course of AD.     

Imaging markers of mild cognitive impairment: multivariate analysis of CBF SPECT

This study aimed to investigate cross-sectional and longitudinal changes of regional cerebral blood flow (rCBF) in preclinical dementia using single photon emission computed tomography (SPECT). SPECT and cognitive function were investigated in 39 mild cognitive impairment (MCI) subjects and 20 age-matched controls. All subjects were followed longitudinally 19 months on average, 16 MCI subjects progressed to Alzheimer's disease (AD), who were retrospectively defined as progressive mild cognitive impairment (PMCI) at baseline and 23 MCI subjects remained stable and were defined as stable mild cognitive impairment (SMCI) at baseline. SPECT was performed both at the initial investigation and at follow-up. Image data were analyzed using multivariate analysis, SPM and volume of interest (VOI)-based analysis. Significant covariate patterns were derived, which differentiate among PMCI, SMCI and controls at baseline as well as describe the longitudinal progression of PMCI. The combined SPECT and neuropsychology increased the diagnostic accuracy of PMCI at baseline. SPECT and neuropsychological testing can be used objectively for both baseline diagnosis and to monitor changes in brain function during very early AD.     

Diagnosing prodromal Alzheimer's disease: role of CSF biochemical markers

Mild cognitive impairment (MCI) is an aetiologically heterogeneous syndrome. A correct prediction of MCI conversion to Alzheimer's disease (AD) represents a primary goal in routine clinical practice. Since the presence of pathological levels in >or=2 cerebrospinal fluid (CSF) biomarkers; amyloid protein (Abeta42), total tau (h-tau) and phospho-tau (p-tau) seems to reliably identifying MCI subjects converting to AD, we report our experience in a routine clinical setting. In the period from January 2001 to June 2003, 273 consecutive patients referred to our Memory Clinic for diagnostic assessment of cognitive impairment. Of them, 180 underwent a complete diagnostic evaluation including CSF dosage of fragment 1-42 of amyloid protein, total tau and phospho-tau (ELISA Method, Innogenetics, Gent, Belgium), after vascular or other secondary causes of dementia could be excluded. At baseline, 38% of the MCI subjects (20/55) showed pathological levels in >or=2 CSF biomarkers. After 1 year, 11 MCI patients converted to dementia, 33 remained stable, 11 showed a further progression of cognitive impairment still not fulfilling the diagnostic criteria for dementia. Of the 11 converters, 10 showed >or=2 pathological values CSF biomarkers and in all of them, p-tau was high. On the contrary, 29 out of 33 stable MCI (88%) showed no or one pathological CSF value. We confirm that pathological levels in >or=2 CSF biomarkers reliably predict MCI conversion to AD and correctly identify the stable form of MCI.     

Seoul Neuropsychological Screening Battery-Dementia Version (SNSB-D): A Useful Tool for Assessing and Monitoring Cognitive Impairments in Dementia Patients

The Seoul Neuropsychological Screening Battery (SNSB) is one of the standardized neuropsychological test batteries widely used in Korea. However, it may be a bit too lengthy for patients with decreased attention span; and it does not provide the score of global cognitive function (GCF), which is useful for monitoring patients longitudinally. We sought to validate a dementia version of SNSB (SNSB-D) that was shorter than the original SNSB and contained only scorable tests with a GCF score of 300. We administered SNSB-D to patients with mild cognitive impairment (MCI) (n=43) and Alzheimer''s disease (AD) (n=93), and normal controls (NC) (n=77). MCI and AD groups had GCF scores significantly different from NC group, and GCF scores were able to distinguish patients with Clinical Dementia Rating of 0.5 and 1. Test-retest reliability was high, with a correlation coefficient of 0.918 for AD, 0.999 for MCI, and 0.960 for NC. The GCF score significantly correlated with the Mini-Mental State Examination (MMSE). Through ROC-curve analysis, GCF scores were found to yield more accurate diagnoses than the MMSE. The SNSB-D is a valid, reliable tool for assessing the overall cognitive function, and can be used to monitor cognitive changes in patients with dementia.     

Prefrontal cortex cytoarchitecture in normal aging and Alzheimer’s disease: a relationship with IQ

We have previously shown that the minicolumnar spacing of neurons in the cerebral cortex relates to cognitive ability, and that minicolumn thinning occurs in old age. The present study examines further the relationship between cognitive ability and cortical fine structure (minicolumn organization and neuropathology) in the dorsolateral prefrontal cortex (dlPFC) and the parahippocampal gyrus (PHG) in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Premortem neuropsychological scores were related to postmortem microanatomy in 58 adults (20 normal controls, 18 MCI, and 20 confirmed AD patients). We found a correspondence between minicolumn thinning in the dlPFC and IQ decline in dementia. In mild impairment, IQ remained stable, as did dlPFC minicolumn width and dlPFC plaque load. IQ only declined as dlPFC minicolumn thinning occurred and dlPFC plaque load increased in more severe dementia. By contrast, plaque load increased and minicolumns became steadily thinner in the PHG, where minicolumn width correlated with declining mini-mental state examination score across both MCI and severe dementia. By including a further 14 younger control subjects, we found that in normal healthy aging, minicolumn width decreased in the dlPFC, whereas PHG minicolumn width did not change. AD patients in our dataset with higher IQ were older at time of death and had less pathology, which supports a neural basis for the cognitive reserve hypothesis.     

Abnormal retinal thickness in patients with mild cognitive impairment and Alzheimer's disease

In Alzheimer's disease (AD), brain lesions are marked by severe neuronal loss and retinal degeneration was previously mentioned in affected patients. Mild cognitive impairment (MCI) is a clinical syndrome that could be an early phase of AD. In this study, using optical coherence tomography (OCT), the retinal nerve fiber layer (RNFL) thickness was assessed in patients with mild AD, moderate to severe AD, amnestic MCI and control subjects. The results show that RNFL thickness is statistically reduced in patients with MCI, mild AD or moderate to severe AD compared to controls. In addition, no statistical difference was found between the results in MCI patients and mild AD patients. The RNFL seems to be involved early during the course of amnestic MCI and OCT tests could be carried out in patients with cognitive troubles.     

MRI of hippocampus and entorhinal cortex in mild cognitive impairment: a follow-up study

The concept of mild cognitive impairment (MCI) has been proposed to represent a transitional stage between normal aging and dementia. We studied the predictive value of the MRI-derived volumes of medial temporal lobe (MTL) structures, white matter lesions (WML), neuropsychological tests, and Apolipoprotein E (APOE) genotype on conversion of MCI to dementia and AD. The study included 60 subjects with MCI identified from population cohorts. During the mean follow-up period of 34 months, 13 patients had progressed to dementia (9 to Alzheimer's disease (AD)). In Cox regression analysis the baseline volumes of the right hippocampus, the right entorhinal cortex and CDR sum of boxes predicted the progression of MCI to dementia during the follow-up. In a bivariate analysis, only the baseline volumes of entorhinal cortex predicted conversion of MCI to AD. The Mini-Mental State Examination (MMSE) score at baseline, WML load, or APOE genotype were not significant predictors of progression. The MTL volumetry helps in identifying among the MCI subjects a group, which is at high risk for developing AD.     

High Activities of BACE1 in Brains with Mild Cognitive Impairment

We recently discovered elevated β-secretase 1 (BACE1) activity in brains with sporadic Alzheimer disease (AD). Moreover, we also found high levels of BACE1 enzymatic activity in the cerebrospinal fluid from patients with both mild cognitive impairment (MCI) and AD. These results suggest that elevation of BACE1 enzymatic activity may occur early or may contribute to AD. We therefore examined whether BACE1 enzymatic activity was changed in MCI brains. BACE1 activity and tumor necrosis factor (TNF)-α levels were measured by enzymatic assay and ELISA in the temporal cortex from 18 patients with clinically well-characterized AD, 18 patients with MCI, and 18 healthy controls. We found a significant increase in BACE1 activity and protein level in brains of MCI and AD patients. Moreover, increased BACE1 activity correlated with plaque numbers and cognition status. We also found an increase in TNF-α in MCI brains. In vitro study revealed that TNF-α rather than other cytokines can up-regulate BACE1 protein expression. These findings suggest that BACE1 increase occurs early in MCI and is possibly induced by TNF-α and that BACE1 enzymatic activity may be important for conversion of MCI to AD.Searching the early events of Alzheimer disease (AD) is becoming critical for effective diagnosis and treatment. Neuritic plaques and neurofibrillary tangles are two major pathologic characteristics of AD and major targets for AD diagnosis. Amyloid β (Aβ) peptide is a major component of neuritic plaques. β-Secretase 1 (BACE1), also known as β-site amyloid precursor protein (APP) cleaving enzyme, is an aspartic protease, a critical enzyme to promote Aβ generation.^1–4 We originally discovered that BACE1 activity and protein expression are significantly increased in AD brains.^5,6 Because the signals from cerebrospinal fluid (CSF) reflect most of neuropathologic changes in AD, we have studied BACE1 activity in the CSF from patients with mild cognitive impairment (MCI) and AD and found elevated BACE1 activity in the CSF of both MCI and AD patients.^7,8 These results indicate that activation of BACE1 may play an important role in the early stage of AD when cognitive deficits are first observed and in progressive dementia associated with AD. However, whether BACE1 enzymatic activity and protein expression were altered in the brain as early as at the MCI stage was not known, possibly because of limits of sources of autopsied brain tissues. To examine whether BACE1 was activated in the brain during the early stages of AD (ie, MCI), we took advantage of the brain bank⁹ of rapidly autopsied MCI and AD brain tissues and biochemically measured BACE1 activity in brains of nondemented (ND) controls, MCI patients, and AD patients. We found that BACE1 enzymatic activity was significantly increased in both MCI and AD brains in the present study. Moreover, we also found that BACE1 activity was positively correlated with numbers of plaques and negatively correlated with Mini-Mental State Examination (MMSE) scores in MCI patients. Interestingly however, we also observed that there was no significant difference in BACE1 activity between MCI and AD patients. Because recent studies demonstrated that BACE1 may affect neuronal activity and brain metabolism,^10–13 we conclude that BACE1 activity precedes the clinical diagnosis of AD and could be an early indicator of neuronal dysfunction or disease in AD.     

Anomalously phosphorylated tau and Abeta fragments in the CSF correlates with cognitive impairment in MCI subjects

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence of extracellular amyloid deposits, consisting largely of Abeta peptide and the presence of intraneuronal aggregates of neurofibillary tangles formed by tau. Development of cerebrospinal fluid (CSF) biomarkers has become a rapidly growing research field, considering the need for diagnostic tools for AD, thus allowing therapeutic compounds to have the greatest potential for being effective. We have focused on the relationships between critical biomarkers such as tau and Abeta in the CSF and the cognitive impairment of patients, as assessed by a battery of neuropsychological tests derived from CDR and CERAD, of value in the evaluation of AD patients. As part of a longitudinal study, we analyzed by ELISA and Western blots the levels and molecular patterns of hyperphosphorylated tau in the CSF of three different groups of patients: AD patients between 69- and 73-years-old, a group characterized with mild cognitive impairment (MCI) between 65- and 70-years-old, and a non-demented neurological control group of comparable ages. The levels of AT8-reactive phosphorylated tau were significantly higher (P<0.05) in AD patients (0.604+/-0.078, n=23) as compared with the control group (0.457+/-0.086, n=25). No differences between the levels of AT8-reactive tau of MCI patients (0.510+/-0.090, n=45) and controls were observed. However, when the MCI group was divided on the basis of the total box score (TBS) from CDR, those subjects with a TBS<1.5 presented tau levels (0.456+/-0.032, n=31) similar to controls, whereas those patients with TBS>or=1.5 displayed tau levels (0.590+/-0.086, n=14) comparable with those of AD. Western blot analyses revealed a higher AT8 reactivity in CSF samples of AD patients as compared with MCI and control samples, indicating higher levels of AD tau phosphoepitopes in the CSF. Tau heterogeneity was observed in samples of AD and MCI with higher impairment as compared with controls. As expected from previous reports, levels of Abeta (1-42) were lower (0.052+/-0.005) than controls (0.070+/-0.010), whereas the levels of MCI group were 0.060+/-0.007. The MCI group with a TBS>or=1.5 presented Abeta levels of 0.053+/-0.005 similar to those of AD patients, whereas the MCI group with TBS<1.5 exhibited Abeta levels (0.066+/-0.007) similar to controls. Studies highlight the relationships between anomalously phosphorylated tau markers in CSF with the information from TBS analysis of the different groups of patients.     

Conversion of MCI to dementia: Role of proton magnetic resonance spectroscopy

Mild cognitive impairment (MCI) represents a heterogeneous group of cognitive disturbances at high risk of dementia. The amnestic subtype (aMCI) might be a prodromal state of Alzheimer's disease (AD). The aim of this study is the identification, by proton magnetic resonance spectroscopy (1H MRS), of modifications in brain metabolites able to detect subjects with aMCI at risk of conversion towards AD. Twenty-five subjects with aMCI and 29 normal elderly were enrolled; they underwent a comprehensive clinical and instrumental assessment, a cerebral 1H MRS scan to measure N-acetyl aspartate (NAA), choline (Cho), myo-inositol (mI) and creatine (Cr) in the paratrigonal white matter, bilaterally. After 1 year, 5 MCI subjects became demented (progressive MCI, pMCI). Their baseline levels of metabolites were compared with those evaluated in stable MCI (sMCI) and in controls. We observed a significant difference of the NAA/Cr ratio between pMCI (1.48+/-0.08) and sMCI (1.65+/-0.12) and between pMCI and controls (1.63+/-0.16) in the left hemisphere, suggesting that this metabolic alteration can be detected before the clinical appearance of dementia.     

Plasma antioxidants are similarly depleted in mild cognitive impairment and in Alzheimer's disease

In order to assess peripheral levels and activities of a broad spectrum of non-enzymatic and enzymatic antioxidants in elderly subjects with mild cognitive impairment (MCI) and Alzheimer's disease (AD), plasma levels of water-soluble (Vitamin C and uric acid) and of lipophilic (Vitamin A, Vitamin E and carotenoids including lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha- and beta-carotene) antioxidant micronutrients as well as activities of plasma and red blood cell (RBC) superoxide dismutase (SOD) and of plasma glutathione peroxidase (GPx) were measured in 25 patients with MCI, 63 AD patients and 53 controls. Peripheral levels and activities of antioxidants were similarly lower in MCI and AD patients as compared to controls. As MCI may represent a prodromal stage of AD, and oxidative damage appears to occur as one of the earliest pathophysiological events in AD, an increased intake of antioxidants in patients with MCI could be helpful in lowering the risk of conversion to dementia.     

White matter changes in mild cognitive impairment and AD: A diffusion tensor imaging study

Diffusion tensor imaging (DTI) can detect, in vivo, the directionality of molecular diffusion and estimate the microstructural integrity of white matter (WM) tracts. In this study, we examined WM changes in patients with Alzheimer's disease (AD) and in subjects with amnestic mild cognitive impairment (MCI) who are at greater risk for developing AD. A DTI index of WM integrity, fractional anisotropy (FA), was calculated in 14 patients with probable mild AD, 14 participants with MCI and 21 elderly healthy controls (NC). Voxel-by-voxel comparisons showed significant regional reductions of FA in participants with MCI and AD compared to controls in multiple posterior white matter regions. Moreover, there was substantial overlap of locations of regional decrease in FA in the MCI and AD groups. These data demonstrate that white matter changes occur in MCI, prior to the development of dementia.