Do white matter changes contribute to the subsequent development of dementia in patients with mild cognitive impairment? A longitudinal study

White matter hyperintensities in dementia with Lewy bodies are associated with poorer cognitive function and higher dementia stages

Purpose

White matter hyperintensities (WMHs) are frequently found in elderly individuals with or without dementia. However, the association between WMHs and clinical presentations of dementia with Lewy bodies (DLB) has rarely been studied.

Methods

We conducted a retrospective analysis of patients with DLB registered in a dementia database. WMHs were rated visually using the Fazekas scale, and its associated factors including dementia severity, cognitive functions, neuropsychiatric symptoms, and core clinical features were compared among different Fazekas scores. Domains in the Clinical Dementia Rating (CDR), Cognitive abilities Screening Instruments (CASI), and Neuropsychiatric Inventory (NPI) were compared among different Fazekas groups after adjusting for age, sex, education, and disease duration.

Results

Among the 449 patients, 76, 207, 110, and 56 had Fazekas score of 0, 1, 2, and 3, respectively. There was a positive association between dementia severity and WMHs severity, and the mean sums of boxes of the Clinical Dementia Rating (CDR-SB) were 5.9, 7.8, 9.5, and 11.2 (f = 16.84, p < 0.001) for the Fazekas scale scores 0, 1, 2, and 3, respectively. There was a negative association between cognitive performance and WMHs severity, and the mean CASI were 57.7, 45.4, 4.06, and 33.4 (f = 14.22, p < 0.001) for the Fazekas scale scores 0, 1, 2, and 3, respectively. However, WMHs were not associated with the core clinical features of DLB. After adjustment, all cognitive domains in CDR increased as the Fazekas score increased. In addition, performance on all cognitive domains in CASI decreased as the Fazekas score increased (all p < 0.001). Among neuropsychiatric symptoms, delusions, euphoria, apathy, aberrant motor behavior, and sleep disorders were significantly worse in the higher Fazekas groups compared to those in the group with Fazekas score of 0 after adjustment.

Conclusion

WMHs in DLB might contribute to deterioration of cognitive function, neuropsychiatric symptoms, and dementia stages. However, core clinical features were not significantly influenced by WMHs in DLB.

Leukoaraiosis and Gray Matter Volume Alteration in Older Adults: The PROOF Study

Background and Purpose: Leukoaraiosis, also called white matter hyperintensities (WMH), is frequently encountered in the brain of older adults. During aging, gray matter structure is also highly affected. WMH or gray matter defects are commonly associated with a higher prevalence of mild cognitive impairment. However, little is known about the relationship between WMH and gray matter. Our aim was thus to explore the relationship between leukoaraiosis severity and gray matter volume in a cohort of healthy older adults.

Methods: Leukoaraiosis was rated in participants from the PROOF cohort using the Fazekas scale. Voxel-based morphometry was performed on brain scans to examine the potential link between WMH and changes of local brain volume. A neuropsychological evaluation including attentional, executive, and memory tests was also performed to explore cognition.

Results: Out of 315 75-year-old subjects, 228 had punctuate foci of leukoaraiosis and 62 had begun the confluence of foci. Leukoaraiosis was associated with a decrease of gray matter in the middle temporal gyrus, in the right medial frontal gyrus, and in the left parahippocampal gyrus. It was also associated with decreased performances in memory recall, executive functioning, and depression.

Conclusion: In a population of healthy older adults, leukoaraiosis was associated with gray matter defects and reduced cognitive performance. Controlling vascular risk factors and detecting early cerebrovascular disease may prevent, at least in part, dementia onset and progression.

Arterial Stiffening Moderates the Relationship Between Type-2 Diabetes Mellitus and White Matter Hyperintensity Burden in Older Adults With Mild Cognitive Impairment

Background: Cerebrovascular dysfunction has been proposed as a possible mechanism underlying cognitive impairment in the context of type 2 diabetes mellitus (DM). Although magnetic resonance imaging (MRI) evidence of cerebrovascular disease, such as white matter hyperintensities (WMH), is often observed in DM, the vascular dynamics underlying this pathology remain unclear. Thus, we assessed the independent and combined effects of DM status and different vascular hemodynamic measures (i.e., systolic, diastolic, and mean arterial blood pressure and pulse pressure index [PPi]) on WMH burden in cognitively unimpaired (CU) older adults and those with mild cognitive impairment (MCI). Methods: 559 older adults (mean age: 72.4 years) from the Alzheimer's Disease Neuroimaging Initiative were categorized into those with diabetes (DM+; CU = 43, MCI = 34) or without diabetes (DM-; CU = 279; MCI = 203). Participants underwent BP assessment, from which all vascular hemodynamic measures were derived. T2-FLAIR MRI was used to quantify WMH burden. Hierarchical linear regression, adjusting for age, sex, BMI, intracranial volume, CSF amyloid, and APOE ε4 status, examined the independent and interactive effects of DM status and each vascular hemodynamic measure on total WMH burden. Results: The presence of DM (p = 0.046), but not PPi values (p = 0.299), was independently associated with greater WMH burden overall after adjusting for covariates. Analyses stratified by cognitive status revealed a significant DM status x PPi interaction within the MCI group (p = 0.001) such that higher PPi values predicted greater WMH burden in the DM + but not DM- group. No significant interactions were observed in the CU group (all ps > 0.05). Discussion: Results indicate that higher PPi values are positively associated with WMH burden in diabetic older adults with MCI, but not their non-diabetic or CU counterparts. Our findings suggest that arterial stiffening and reduced vascular compliance may have a role in development of cerebrovascular pathology within the context of DM in individuals at risk for future cognitive decline. Given the specificity of these findings to MCI, future exploration of the sensitivity of earlier brain markers of vascular insufficiency (i.e., prior to macrostructural white matter changes) to the effects of DM and arterial stiffness/reduced vascular compliance in CU individuals is warranted.

The Contribution of Small Vessel Disease to Neurodegeneration: Focus on Alzheimer's Disease, Parkinson's Disease and Multiple Sclerosis

Brain small vessel disease (SVD) refers to a variety of structural and functional changes affecting small arteries and micro vessels, and manifesting as white matter changes, microbleeds and lacunar infarcts. Growing evidence indicates that SVD might play a significant role in the neurobiology of central nervous system (CNS) neurodegenerative disorders, namely Alzheimer's disease (AD) and Parkinson's disease (PD), and neuroinflammatory diseases, such as multiple sclerosis (MS). These disorders share different pathophysiological pathways and molecular mechanisms (i.e., protein misfolding, derangement of cellular clearance systems, mitochondrial impairment and immune system activation) having neurodegeneration as biological outcome. In these diseases, the actual contribution of SVD to the clinical picture, and its impact on response to pharmacological treatments, is not known yet. Due to the high frequency of SVD in adult-aged patients, it is important to address this issue. In this review, we report preclinical and clinical data on the impact of SVD in AD, PD and MS, with the main aim of clarifying the predictability of SVD on clinical manifestations and treatment response.

Effects of White Matter Hyperintensities on Verbal Fluency in Healthy Older Adults and MCI/AD

BACKGROUND

White matter hyperintensities (WMHs) are markers for cerebrovascular pathology, which are frequently seen in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Verbal fluency is often impaired especially in AD, but little research has been conducted concerning the specific effects of WMH on verbal fluency in MCI and AD.

OBJECTIVE

Our aim was to examine the relationship between WMH and verbal fluency in healthy old age and pathological aging (MCI/AD) using quantified MRI data.

METHODS

Measures for semantic and phonemic fluency as well as quantified MRI imaging data from a sample of 42 cognitively healthy older adults and 44 patients with MCI/AD (total n = 86) were utilized. Analyses were performed both using the total sample that contained seven left-handed/ambidextrous participants, as well with a sample containing only right-handed participants (n = 79) in order to guard against possible confounding effects regarding language lateralization.

RESULTS

After controlling for age and education and adjusting for multiple correction, WMH in the bilateral frontal and parieto-occipital areas as well as the right temporal area were associated with semantic fluency in cognitively healthy and MCI/AD patients but only in the models containing solely right-handed participants.

CONCLUSION

The results indicate that white matter pathology in both frontal and parieto-occipital cerebral areas may have associations with impaired semantic fluency in right-handed older adults. However, elevated levels of WMH do not seem to be associated with cumulative effects on verbal fluency impairment in patients with MCI or AD. Further studies on the subject are needed.

Evidence of a Relation Between Hippocampal Volume, White Matter Hyperintensities, and Cognition in Subjective Cognitive Decline and Mild Cognitive Impairment

OBJECTIVE

The concepts of mild cognitive impairment (MCI) and subjective cognitive decline (SCD) have been proposed to identify individuals in the early stages of Alzheimer's disease (AD), or other neurodegenerative diseases. One approach to validate these concepts is to investigate the relationship between pathological brain markers and cognition in those individuals.

METHOD

We included 126 participants from the Consortium for the Early Identification of Alzheimer's disease-Quebec (CIMA-Q) cohort (67 SCD, 29 MCI, and 30 cognitively healthy controls [CH]). All participants underwent a complete cognitive assessment and structural magnetic resonance imaging. Group comparisons were done using cognitive data, and then correlated with hippocampal volumes and white matter hyperintensities (WMHs).

RESULTS

Significant differences were found between participants with MCI and CH on episodic and executive tasks, but no differences were found when comparing SCD and CH. Scores on episodic memory tests correlated with hippocampal volumes in both MCI and SCD, whereas performance on executive tests correlated with WMH in all of our groups.

DISCUSSION

As expected, the SCD group was shown to be cognitively healthy on tasks where MCI participants showed impairment. However, SCD's hippocampal volume related to episodic memory performances, and WMH to executive functions. Thus, SCD represents a valid research concept and should be used, alongside MCI, to better understand the preclinical/prodromal phase of AD.

White-matter changes in early and late stages of mild cognitive impairment

Mild Cognitive Impairment (MCI) is characterized by cognitive deficits that exceed age-related decline, but not interfering with daily living activities. Amnestic type of the disorder (aMCI) is known to have a high risk to progress to Alzheimer's Disease (AD), the most common type of dementia. Identification of very early structural changes in the brain related to the cognitive decline in MCI patients would further contribute to the understanding of the dementias. In the current study, we target to investigate whether the white-matter changes are related to structural changes, as well as the cognitive performance of MCI patients. Forty-nine MCI patients were classified as Early MCI (E-MCI, n = 24) and Late MCI (L-MCI, n = 25) due to their performance on The Free and Cued Selective Reminding Test (FCSRT). Age-Related White-Matter Changes (ARWMC) scale was used to evaluate the white-matter changes in the brain. Volumes of specific brain regions were calculated with the FreeSurfer program. Both group and correlation analyses were conducted to show if there was any association between white-matter hyperintensities (WMHs) and structural changes and cognitive performance. Our results indicate that, L-MCI patients had significantly more WMHs not in all but only in the frontal regions compared to E-MCI patients. Besides, ARWMC scores were not correlated with total hippocampal and white-matter volumes. It can be concluded that WMHs play an important role in MCI and cognitive functions are affected by white-matter changes of MCI patients, especially in the frontal regions.

Genome-wide association study of white matter hyperintensity volume in elderly persons without dementia

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We conducted a GWAS to identify genetic loci linked to WMHV in non-demented elders.

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Rs7220676 near HS3ST3A1 and MIR548H3 genes was significantly associated with WMHV.

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Rs7220676 was also correlated with rates of cognitive decline.

Background

White matter hyperintensity has been correlated with cognitive disorders and its genetic predictors remain unclear. Here we conducted a genome-wide association study to identify novel genetic determinants that were correlated with white matter hyperintensity volume (WMHV) among non-demented elders.

Methods

Three hundred and fifty non-Hispanic Caucasian subjects aged 55–80 years were included from the Alzheimer's Disease Neuroimaging Initiative cohort. Associations of WMHV with genetic polymorphisms were explored using multiple linear regression under an additive genetic model. Further studies were conducted to explore the influence of genetic variants on cognition-related phenotypes.

Results

Rs7220676 near HS3ST3A1 and MIR548H3 genes was associated with WMHV levels at genome-wide significance (P = 2.96 × 10⁻⁸). Single nucleotide polymorphisms comprising rs9675262 (near HS3ST3A1 and MIR548H3 genes, P = 1.15 × 10⁻⁷), rs9820240 (in DCLK3 gene, P = 2.23 × 10⁻⁷), rs10916409 (near ISCA1P2 gene, P = 4.55 × 10⁻⁶), and rs540422 (in PICALM gene, P = 9.68 × 10⁻⁶) were identified as suggestive loci linked to WMHV levels. The minor allele of rs7220676 (C) showed association with lower log (WMHV) in a dose-dependent manner. Besides, rs7220676 was correlated with rates of cognitive decline assessed by Mini-mental State Examination and memory scores.

Conclusions

A novel locus near HS3ST3A1 and MIR548H3 genes was associated with WMHV levels and it may be involved in neurodegenerative diseases.

Domain-specific cognitive effects of white matter pathology in old age, mild cognitive impairment and Alzheimer's disease

Concomitant white matter (WM) brain pathology is often present in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Cognitive effects of WM pathology on cognition in normal and pathological aging have been studied, but very little is known about possible group-specific effects in old age, MCI and AD. The purpose of the current study was to examine the relationship between WM pathology and cognitive functioning in four cognitive domains in old age, MCI and AD. The study utilized multi-domain neuropsychological data and visually rated MRI imaging data from a sample of 56 healthy older adults, 40 patients with MCI and 52 patients with AD (n = 148). After controlling for age and education, main effects of frontal WM pathology (especially in the left hemisphere) were found for cognitive performances in two domains, whereas a main effect of parieto-occipital WM pathology was only found for processing speed. In addition, with regard to processing speed, an interaction between group and WM changes was found: Patients with AD that had moderate or severe left frontal WM pathology were considerably slower than patients with AD that had milder cerebrovascular pathology. Frontal WM pathology, especially in the left hemisphere, seems to affect cognitive functions in many domains in all three groups. The results of the study increase our knowledge of cognitive repercussions stemming from frontal and/or parieto-occipital WM pathology in AD. Clinicians should be aware that patients with AD with prominent frontal cerebrovascular pathology can have considerably slowed cognitive processing.

Increased risk of dementia in patients with Schizophrenia: A population-based cohort study in Taiwan

Background:

The extent to which schizophrenia is associated with the risk of all-cause dementia is controversial. This study investigated the risk of dementia by type in patients with schizophrenia.

Methods:

Data were collected from the Taiwanese National Health Insurance Database 2005 and analyzed using multivariate Cox proportional hazard regression models to determine the effect of schizophrenia on the dementia risk after adjusting for demographic characteristics, comorbidities, and medications. Fine and Gray's competing risk analysis was used to determine the risk of dementia, as death can act as a competing risk factor for dementia.

Results:

We assessed 6040 schizophrenia patients and 24,160 propensity scale-matched control patients. Schizophrenia patients exhibited a 1.80-fold risk of dementia compared to controls (adjusted hazard ratio [aHR] = 1.80, 95% confidence interval [CI] = 1.36 ∼ 2.21,p <0.001) after adjusting for covariates. Cardiovascular disease (aHR = 5.26; 95% CI = 4.50 ∼ 6.72;p <0.001), hypertension (aHR = 1.83; 95% CI = 1.77 ∼ 2.04;p= 0.002), traumatic head injury (aHR = 1.35; 95% CI = 1.24 ∼ 1.78;p <0.001), chronic lung diseases (aHR = 1.64; 95% CI = 1.13 ∼ 2.56;p <0.001), alcohol-related disorders (aHR = 3.67; 95% CI = 2.68 ∼ 4.92;p <0.001), and Parkinson’s disease (aHR = 1.72; 95% CI = 1.25 ∼ 2.40;p <0.001) were significantly associated with dementia risk. Notably, first-generation antipsychotics (aHR = 0.80; 95% CI = 0.56 ∼ 0.95;p=0.044) and second-generation antipsychotics (aHR = 0.24; 95% CI = 0.11 ∼ 0.60;p <0.001) were associated with a lower dementia risk. Sensitivity tests yielded consistent findings after excluding the first year and first 3 years of observation. Patients with schizophrenia had the highest risk of developing Alzheimer’s [dementia/disease?] among dementia subtypes (aHR = 2.10; 95% CI = 1.88 ∼ 3.86;p< 0.001), followed by vascular dementia (aHR = 1.67; 95% CI = 1.27 ∼ 2.12;p< 0.001) and unspecified dementia (aHR = 1.30; 95% CI = 1.04 ∼ 2.01;p< 0.001).

Conclusions:

Schizophrenia was significantly associated with the risk of all-cause dementia. Data are scarce on the mechanisms through which antipsychotic agents protect persons with schizophrenia from developing dementia. Further research is recommended to elucidate the neurobiological mechanisms underlying the association between schizophrenia and dementia, and whether antipsychotics protect against the development of dementia in schizophrenia.

Cerebral small vessel disease and the risk of dementia: A systematic review and meta-analysis of population-based evidence

INTRODUCTION

Cerebral small vessel disease is increasingly linked to dementia.

METHODS

We systematically searched Medline, Embase, and Cochrane databases for prospective population-based studies addressing associations of white matter hyperintensities, covert brain infarcts (i.e., clinically silent infarcts), and cerebral microbleeds with risk of all-dementia or Alzheimer's disease and performed meta-analyses.

RESULTS

We identified 11 studies on white matter hyperintensities, covert brain infarcts, or cerebral microbleeds with risk of all-dementia or Alzheimer's disease. Pooled analyses showed an association of white matter hyperintensity volume and a borderline association of covert brain infarcts with risk of all-dementia (hazard ratio: 1.39 [95% confidence interval: 1.00; 1.94], N = 3913, and 1.47 [95% confidence interval: 0.97; 2.22], N = 8296). Microbleeds were not statistically significantly associated with an increased risk of all-dementia (hazard ratio: 1.25 [95% confidence interval: 0.66; 2.38], N = 8739).

DISCUSSION

White matter hyperintensities are associated with an increased risk of all-dementia and Alzheimer's disease in the general population. However, studies are warranted to further determine the role of markers of cerebral small vessel disease in dementia.

White matter abnormalities and cognition in patients with conflicting diagnoses and CSF profiles

OBJECTIVE

To determine whether white matter changes influence progression of cognitive decline in individuals with clinically diagnosed Alzheimer disease (AD) and differing biomarker profiles.

METHODS

Two hundred thirty-six individuals from the Alzheimer's Disease Neuroimaging Initiative database with clinical diagnoses of cognitively normal older adult (older controls [OCs]), mild cognitive impairment, and AD were studied. Support vector machine experiments were first performed to determine the utility of various biomarkers for classifying individuals by clinical diagnosis. General linear models were implemented to assess the relationships between CSF measures of β-amyloid 1-42, phosphorylated tau_181p, and MRI-based white matter signal abnormality (WMSA) volumes and cognitive decline. Analyses were performed across all patients as well as within subgroups of individuals that were defined by clinical cutoff points for both CSF measures.

RESULTS

CSF biomarkers alone classified individuals with AD vs OCs with 82% accuracy, and the addition of WMSA did not enhance this. Both CSF biomarkers as well as WMSA volume significantly contributed to predicting cognitive decline in executive and memory domains when assessed across all 236 individuals. In individuals with pathologic levels of both CSF biomarkers, WMSA only significantly contributed to models of future executive function decline. In individuals with subpathologic CSF biomarker levels (levels similar to those in OC individuals), WMSA significantly contributed to prediction of memory decline and were the sole significant predictor of executive function decline.

CONCLUSIONS

WMSA hold additional predictive power regarding cognitive progression in older individuals and are most effective as biomarkers in individuals who are cognitively impaired but do not fit the expected CSF biomarker profile of AD.

Effects of white matter lesions on brain perfusion in patients with mild cognitive impairment

OBJECTIVE

To evaluate the effects of white matter lesions on regional cerebral blood flow in subjects with amnestic mild cognitive impairment.

PATIENTS AND METHODS

Seventy-five subjects with mild cognitive impairment (36 men and 39 women; mean age, 78.1 years) were included in the study. We used the Mini-Mental State Examination to assess cognitive function. All subjects underwent brain magnetic resonance imaging and ^99mTc ethylcysteinate dimer single photon emission computed tomography. Subjects were stratified based on the presence or absence of white matter lesions on magnetic resonance imaging. Statistical parametric mapping of differences in regional cerebral blood flow between the two groups were assessed by voxel-by-voxel group analysis using SPM8.

RESULTS

Of all 75 subjects with mild cognitive impairment, 46 (61.3%) had mild to moderate white matter lesions. The prevalence of hypertension tended to be higher in subjects with white matter lesions than in those without white matter lesions. Mini-Mental State Examination scores were significantly lower in subjects with white matter lesions than in those without white matter lesions. Subjects with white matter lesions had decreased regional cerebral blood flow mainly in the frontal, parietal, and medial temporal lobes, as well as the putamen, compared to those without white matter lesions.

CONCLUSION

In subjects with mild cognitive impairment, white matter lesions were associated with cognitive impairment and mainly frontal lobe brain function.

Excessive variability in systolic blood pressure that is self-measured at home exacerbates the progression of brain white matter lesions and cognitive impairment in the oldest old

To investigate the effects of variability in self-measured systolic blood pressure at home on the progression of cognitive impairment and white matter lesions in the oldest old. Between April 2009 and October 2009, 248 oldest old aged 80 years or older were eligibly enrolled from geriatric practices and community-dwelling areas of Shandong, China. Self-measured blood pressure at home (HBP) was measured for 7 consecutive days at the baseline, and the Mini-Mental State Examination (MMSE) score and brain white matter hyperintensities (WMH) were assessed at the baseline and during the final follow-up visit. Variability in systolic HBP was evaluated using coefficient of variation (CV) in serial daily systolic HBP measurements of the last 6 consecutive days. After an average of 2.3 years of follow-up visits, 232 oldest old were included in and 16 were excluded from the analysis. The MMSE score declined -4.76 (interquartile ranges: -10.71, -0.83) %, the periventricular WMH, deep WMH, total WMH and WMH fraction increased 16.46 (s.d.: 6.72)%, 10.05 (s.d.: 6.40)%, 14.69 (s.d.: 6.07)% and 15.95 (s.d.: 6.32)%, respectively, in the total oldest old. A declined percentage of the MMSE score and increased percentages of the periventricular WMH, deep WMH, total WMH and WMH fraction in the high group divided by tertile of the CV of the systolic HBP at baseline were greater than those in the low group (P<0.05). The significant differences were retained after adjusting for covariates, including the MMSE score, periventricular WMH, deep WMH and WMH fraction at the baseline (P<0.05). Excessive variability in self-measured systolic HBP exacerbates the progression of cognitive impairment and brain white matter lesions in the oldest old.

Multimodality Imaging Approach in Alzheimer disease. Part I: Structural MRI, Functional MRI, Diffusion Tensor Imaging and Magnetization Transfer Imaging

The authors make a complete review of the potential clinical applications of traditional and novel magnetic resonance imaging (MRI) techniques in the evaluation of patients with Alzheimer's disease, including structural MRI, functional MRI, diffusion tension imaging and magnetization transfer imaging.

White matter signal abnormality quality differentiates mild cognitive impairment that converts to Alzheimer's disease from nonconverters

The objective of this study was to assess how longitudinal change in the quantity and quality of white matter signal abnormalities (WMSAs) contributes to the progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). The Mahalanobis distance of WMSA from normal-appearing white matter using T1-, T2-, and proton density-weighted MRI was defined as a quality measure for WMSA. Cross-sectional analysis of WMSA volume in 104 cognitively healthy older adults, 116 individuals with MCI who converted to AD within 3 years (mild cognitive impairment converter [MCI-C]), 115 individuals with MCI that did not convert in that time (mild cognitive impairment nonconverter [MCI-NC]), and 124 individuals with AD from the Alzheimer's Disease Neuroimaging Initiative revealed that WMSA volume was substantially greater in AD relative to the other groups but did not differ between MCI-NC and MCI-C. Longitudinally, MCI-C exhibited faster WMSA quality progression but not volume compared with matched MCI-NC beginning 18 months before MCI-C conversion to AD. The strongest difference in rate of change was seen in the time period starting 6 months before MCI-C conversion to AD and ending 6 months after conversion (p < 0.001). The relatively strong effect in this time period relative to AD conversion in the MCI-C was similar to the relative rate of change in hippocampal volume, a traditional imaging marker of AD pathology. These data demonstrate changes in white matter tissue properties that occur within WMSA in individuals with MCI that will subsequently obtain a clinical diagnosis of AD within 18 months. Individuals with AD have substantially greater WMSA volume than all MCI suggesting that there is a progressive accumulation of WMSA with progressive disease severity, and that quality change predates changes in this total volume. Given the timing of the changes in WMSA tissue quality relative to the clinical diagnosis of AD, these findings suggest that WMSAs are a critical component for this conversion and are a critical component of this clinical syndrome.

Potential benefits of mindfulness-based interventions in mild cognitive impairment and Alzheimer's disease: an interdisciplinary perspective

The present article is based on the premise that the risk of developing Alzheimer's disease (AD) from its prodromal phase (mild cognitive impairment; MCI) is higher when adverse factors (e.g., stress, depression, and metabolic syndrome) are present and accumulate. Such factors augment the likelihood of hippocampal damage central in MCI/AD aetiology, as well as compensatory mechanisms failure triggering a switch toward neurodegeneration. Because of the devastating consequences of AD, there is a need for early interventions that can delay, perhaps prevent, the transition from MCI to AD. We hypothesize that mindfulness-based interventions (MBI) show promise with regard to this goal. The present review discusses the associations between modifiable adverse factors and MCI/AD decline, MBI's impacts on adverse factors, and the mechanisms that could underlie the benefits of MBI. A schematic model is proposed to illustrate the course of neurodegeneration specific to MCI/AD, as well as the possible preventive mechanisms of MBI. Whereas regulation of glucocorticosteroids, inflammation, and serotonin could mediate MBI's effects on stress and depression, resolution of the metabolic syndrome might happen through a reduction of inflammation and white matter hyperintensities, and normalization of insulin and oxidation. The literature reviewed in this paper suggests that the main reach of MBI over MCI/AD development involves the management of stress, depressive symptoms, and inflammation. Future research must focus on achieving deeper understanding of MBI's mechanisms of action in the context of MCI and AD. This necessitates bridging the gap between neuroscientific subfields and a cross-domain integration between basic and clinical knowledge.

Neurosonological Examination: A Non-Invasive Approach for the Detection of Cerebrovascular Impairment in AD

There has been a growing interest in vascular impairment associated with Alzheimer’s disease (AD). This interest was stimulated by the findings of higher incidence of vascular risk factors in AD. Signs of vascular impairment were investigated notably in the field of imaging methods. Our aim was to explore ultrasonographic studies of extra- and intracranial vessels in patients with AD and mild cognitive impairment (MCI) and define implications for diagnosis, treatment, and prevention of the disease. The most frequently studied parameters with extracranial ultrasound are intima-media thickness in common carotid artery, carotid atherosclerosis, and total cerebral blood flow. The transcranial ultrasound concentrates mostly on flow velocities, pulsatility indices, cerebrovascular reserve capacity, and cerebral microembolization. Studies suggest that there is morphological and functional impairment of cerebral circulation in AD compared to healthy subjects. Ultrasound as a non-invasive method could be potentially useful in identifying individuals in a higher risk of progression of cognitive decline.

Contemplating Alzheimer's disease and the contribution of white matter hyperintensities

As the older adult segment of the population increases, Alzheimer's disease (AD) has emerged as a significant public health epidemic. Over the past 3 decades, advances in the understanding of the biology of AD have led to a somewhat unified hypothesis of disease pathogenesis that emphasizes the precipitating role of beta amyloid protein. However, several lines of evidence suggest that multiple pathologies are necessary for clinical manifestation of the disease. Our focus over the past several years has been on the contribution of small vessel cerebrovascular disease, visualized as white matter hyperintensities (WMH) on magnetic resonance imaging, to AD. White matter hyperintensity volume, particularly in parietal regions, is elevated among individuals with and at risk for AD, predicts future diagnosis of AD, predicts the rate of progression of cognitive symptoms among individuals with AD, and increases over time among individuals destined to develop AD. White matter hyperintensities may represent an independent source of impairment and/or may interact more fundamentally with "primary" AD pathology. Future work should focus on more inclusive models of that better define "normal" vs "pathological" aging.

Risk factors for the progression of mild cognitive impairment to dementia

The increasing prevalence of cognitive impairment among the older adult population warrants attention to the identification of practices that may minimize the progression of early forms of cognitive impairment, including the transitional stage of mild cognitive impairment (MCI), to permanent stages of dementia. This article identifies both markers of disease progress and risk factors linked to the progression of MCI to dementia. Potentially modifiable risk factors may offer researchers a point of intervention to modify the effect of the risk factor and to minimize the future burden of dementia.

Does vascular burden contribute to the progression of mild cognitive impairment to dementia?

AIMS

To investigate the contribution of vascular risk factors (VRFs), vascular diseases (VDs) and white matter lesions (WMLs) to the progression of mild cognitive impairment (MCI) to dementia and Alzheimer's disease (AD).

METHODS

Two hundred forty-five consecutive subjects with MCI (age 74.09 ± 6.92 years) were followed for an average of 2.4 years. The Hachinski Ischemic Score and the Framingham Stroke Risk Profile were used to summarize VRFs and VDs. WMLs were graded using the Age-Related White Matter Changes Scale.

RESULTS

One hundred twenty-nine (52.6%) out of 245 subjects at risk converted to dementia, including 87 cases of AD. When hypertension occurred in MCI with deep WMLs, a 1.8-fold increased risk of dementia was observed (95% CI = 1.0-3.4). When deep WMLs occurred in MCI with high scores (≥4) on the Hachinski scale, a 3.5-fold (95% CI = 1.6-7.4) and 3.8-fold (95% CI = 1.2-11.5) risk of progression to dementia and AD was observed, respectively. Analogously, the joint effect of WMLs and high scores (≥14) on the Framingham scale nearly doubled the risk of dementia (hazard ratio = 1.9, 95% CI = 1.1-3.3).

CONCLUSIONS

Accelerated progression of MCI to dementia and AD is to be expected when VRFs and VDs occur together with WMLs.

Tau pathology and parietal white matter lesions have independent but synergistic effects on early development of Alzheimer's disease

BACKGROUND

White matter lesions (WMLs) are a common finding in patients with dementia. This study investigates the relationship between WMLs, hyperphosphorylated tau (P-tau) in cerebrospinal fluid (CSF) and apolipoprotein E (APOE) ε4 genotype in prodromal Alzheimer's disease (AD).

METHODS

Baseline levels of tau, P-tau and β-amyloid 1-42 in CSF, the presence of WMLs in the brain, and the APOE genotype were ascertained in 159 patients with mild cognitive impairment (MCI) and 38 cognitively healthy controls.

RESULTS

After 5.7 years, 58 patients had developed AD. In this group, patients with normal levels of CSF P-tau had higher levels of WMLs in the parietal regions than those with pathological P-tau levels (p < 0.05). Also, patients without APOE ε4 alleles had more WMLs in the parietal lobes than those with at least one allele (p < 0.05). MCI patients with pathological P-tau levels and parietal WMLs showed a greater risk of developing AD than those with just one of the two pathological parameters.

CONCLUSIONS

We suggest that WMLs in parietal lobes and tau pathology likely have independent but synergistic effects on the reduction of the cognitive reserve capacity of the brain. In patients with a more low-grade AD pathology, WMLs in the parietal lobes might increase the risk of developing dementia.

Do cerebral white matter lesions influence the rate of progression from mild cognitive impairment to dementia?

BACKGROUND

Cerebral white matter lesions (WML), evident on CT and MRI brain scans, are histopathologically heterogeneous but associated with vascular risk factors and thought mainly to indicate ischemic damage. There has been disagreement over their clinical prognostic value in predicting conversion from mild cognitive impairment (MCI) to dementia.

METHODS

We scrutinised and rated CT and MRI brain scans for degree of WML in a memory clinic cohort of 129 patients with at least 1 year of follow-up. We examined the relationship between WML severity and time until conversion to dementia for all MCI patients and for amnestic (aMCI) and non-amnestic (naMCI) subgroups separately.

RESULTS

Five-year outcome data were available for 87 (67%) of the 129 patients. The proportion of patients converting to dementia was 25% at 1 year and 76% at 5 years. Patients with aMCI converted to dementia significantly earlier than those with naMCI. WML severity was not associated with time to conversion to dementia for either MCI patients in general or aMCI patients in particular. Among naMCI patients, there was a tendency for those with a low degree of WML to survive without dementia for longer than those with a high degree of WML. However, this was not statistically significant.

CONCLUSIONS

MCI subtype is a significant independent predictor of conversion to dementia, with aMCI patients having higher risk than naMCI for conversion throughout the 5-year follow-up period. WML severity does not influence conversion to dementia for aMCI but might accelerate progression in naMCI.

Mild cognitive impairment: historical development and summary of research

This review article broadly traces the historical development, diagnostic criteria, clinical and neuropathological characteristics, and treatment strategies related to mild cognitive impairment (MCI), The concept of MCI is considered in the context of other terms that have been developed to characterize the elderly with varying degrees of cognitive impairment Criteria based on clinical global scale ratings, cognitive test performance, and performance on other domains of functioning are discussed. Approaches employing clinical, neuropsychological, neuroimaging, biological, and molecular genetic methodology used in the validation of MCI are considered, including results from cross-sectional, longitudinal, and postmortem investigations. Results of recent drug treatment studies of MCI and related methodological issues are also addressed.

Current status and future perspectives of magnetic resonance high-field imaging: a summary

There are several magnetic resonance (MR) imaging techniques that benefit from high-field MR imaging. This article describes a range of novel techniques that are currently being used clinically or will be used in the future for clinical purposes as they gain popularity. These techniques include functional MR imaging, diffusion tensor imaging, cortical thickness assessment, arterial spin labeling perfusion, white matter hyperintensity lesion assessment, and advanced MR angiography.

Review of cerebral microangiopathy and Alzheimer's disease: relation between white matter hyperintensities and microbleeds

Although Alzheimer's disease (AD) is basically considered to be a neurodegenerative disorder, cerebrovascular disease is also involved. The role of vascular risk factors and vascular disease in the progression of AD remains incompletely understood. With the development of brain MRI, it is now possible to detect small-vessel disease, whose prevalence and severity increase with age. The first types of small-vessel disease to be described were white matter hyperintensities (WMHs). More recently, small areas of signal loss on T(2)*-weighted images, also called microbleeds (MBs), have been reported. Cerebral MBs are focal deposits of hemosiderin that indicate prior microhemorrhages around small vessels, related to either ruptured atherosclerotic microvessels or amyloid angiopathy. Consequently, using brain MRI for the detection of microangiopathy may prove useful to improve our understanding of the impact of the vascular burden in AD pathology. The relationship between microangiopathy and the clinical course of AD or the conversion of mild cognitive impairment to AD remains questionable in terms of cognitive or affective symptoms, particularly if we consider MBs.

Plasma homocysteine, brain imaging and cognition in older patients with mental illness

BACKGROUND

Total plasma homocysteine (tHcy) concentration is elevated in older patients with mental illness, and patients with vascular disease have higher plasma tHcy concentration than patients without vascular disease. Plasma tHcy has been reported to be associated with cognitive functions. The mechanism by which plasma tHcy may influence cognitive functions is not clear.

METHOD

We have investigated the relation between plasma tHcy, brain imaging findings (computer tomography scan [CT]) and cognition, measured as Mini mental state examination (MMSE), in 395 consecutively enrolled older patients with mental illness.

RESULTS

Age and plasma tHcy were significant predictors of MMSE score, whereas pathological CT findings, indicating cerebrovascular disease, showed no prediction of MMSE score.

CONCLUSION

The relation between plasma tHcy and cognition is not mediated by cerebrovascular disease as evaluated by pathological CT findings.

Executive function mediates effects of white matter hyperintensities on episodic memory

This study examined the relationship between white matter hyperintensities (WMH) and executive functioning on episodic memory in a group of older adults who were cognitively normal or diagnosed with MCI or dementia. Volumetric magnetic resonance imaging (MRI) measures of total brain volume, white matter hyperintensity volume, and hippocampal volume along with age, education, and gender were evaluated as predictors of episodic memory. WMH were found to influence both episodic memory and executive functioning independently of other variables. The influence WMH on episodic memory was mediated by executive functioning and was completely eliminated when the interaction between executive functioning and hippocampal volume was entered in the regression model. The results indicate that executive functioning mediates the effects of WMH on episodic memory but that executive functioning and hippocampal volume can also interact such that executive functioning can exacerbate or ameliorate the influence of hippocampal volume on episodic memory.

Neurocognitive dysfunction associated with sleep quality and sleep apnea in patients with mild cognitive impairment

OBJECTIVES

Sleep apnea syndrome (SAS) is considered a risk factor for cognitive decline in the elderly. The specific neurocognitive decline has been suggested as a predictive factor for dementia in patients with mild cognitive impairment (MCI). The authors aim to illustrate the sleep characteristics related to the specific neurocognitive decline in the community-dwelling elderly including patients with MCI.

DESIGN

Cross-sectional.

SETTINGS

Center for sleep and chronobiology in Kangwon National University Hospital.

PARTICIPANTS

Thirty patients with MCI and 30 age- and sex-matched normal elderly subjects were selected.

MEASUREMENTS

The authors administered seven tests in the Korean version of the Consortium to Establish A Registry of Alzheimer's Disease Neuropsychological battery and conducted nocturnal polysomnography. A p value below 0.05 was considered a statistical significance.

RESULTS

There was no significant difference in sleep parameters between the MCI and normal comparison (NC) groups. Sleep efficiency was positively correlated with Constructional Recall (CR) scores in both NC and MCI groups (r = 0.393 and 0.391, respectively). The amount of slow wave sleep (SWS) was also positively correlated with Boston naming test (BNT) scores in both groups (r = 0.392, 0.470, respectively). Stepwise multiple regression models showed that SWS and the apnea index were significant independent variables associated with the BNT score (Δβ = 0.43 and -0.34, respectively; adjusted R = 0.298) in the MCI group, and the amount of rapid eye movement sleep was a significant independent variable associated with the CR score (Δβ = 0.49; adjusted R = 0.217) in the NC group.

CONCLUSIONS

Our results show that poor sleep quality and greater severity of SAS were associated with impaired language function reflecting frontal-subcortical pathology in patients with MCI. This suggests that vulnerability to a specific brain damage associated with SAS could increase the risk for dementia.

Distinctive RNA expression profiles in blood associated with white matter hyperintensities in brain

BACKGROUND AND PURPOSE

White matter hyperintensities (WMH) are areas of high signal detected by T2 and fluid-attenuated inversion recovery sequences on brain MRI. Although associated with aging, cerebrovascular risk factors, and cognitive impairment, the pathogenesis of WMH remains unclear. Thus, RNA expression was assessed in the blood of individuals with and without extensive WMH to search for evidence of oxidative stress, inflammation, and other abnormalities described in WMH lesions in brain.

METHODS

Subjects included 20 with extensive WMH (WMH+), 45% of whom had Alzheimer disease, and 18 with minimal WMH (WMH-), 44% of whom had Alzheimer disease. All subjects were clinically evaluated and underwent quantitative MRI. Total RNA from whole blood was processed on human whole genome Affymetrix HU133 Plus 2.0 microarrays. RNA expression was analyzed using an analysis of covariance.

RESULTS

Two hundred forty-one genes were differentially regulated at ± 1.2-fold difference (P < 0.005) in subjects with WMH+ as compared to WMH-, regardless of cognitive status and 50 genes were differentially regulated with ± 1.5-fold difference (P < 0.005). Cluster and principal components analyses showed that the expression profiles for these genes distinguished WMH+ from WMH- subjects. Function analyses suggested that WMH-specific genes were associated with oxidative stress, inflammation, detoxification, and hormone signaling, and included genes associated with oligodendrocyte proliferation, axon repair, long-term potentiation, and neurotransmission.

CONCLUSIONS

The unique RNA expression profile in blood associated with WMH is consistent with roles of systemic oxidative stress and inflammation, as well as other potential processes in the pathogenesis or consequences of WMH.

Association between white matter hyperintensities and executive decline in mild cognitive impairment is network dependent

White matter hyperintensities (WMH) in Mild Cognitive Impairment (MCI) have been associated with impaired executive functioning, although contradictory findings have been reported. The aim of this study was to examine whether WMH location influenced the relation between WMH and executive functioning in MCI participants (55-90 years) in the European multicenter memory-clinic-based DESCRIPA study, who underwent MRI scanning at baseline (N = 337). Linear mixed model analysis was performed to test the association between WMH damage in three networks (frontal-parietal, frontal-subcortical and frontal-parietal-subcortical network) and change in executive functioning over a 3-year period. WMH in the frontal-parietal and in the frontal-parietal-subcortical network were associated with decline in executive functioning. However, the frontal-subcortical network was not associated with change in executive functioning. Our results suggest that parietal WMH are a significant contributor to executive decline in MCI and that investigation of WMH in the cerebral networks supporting cognitive functions provide a new way to differentiate stable from cognitive declining MCI individuals.

The determinants and longitudinal course of post-stroke mild cognitive impairment

While post-stroke dementia has been extensively investigated, the large number of patients with mild cognitive impairment (MCI) following stroke has received less attention, and reports on the longitudinal course of such impairment are inconsistent in their findings. We examined patients with MCI (n = 45) or no cognitive impairment (NCI) (n = 59), based on consensus criteria following detailed neuropsychological assessments and magnetic resonance imaging (MRI) scans, and compared them with healthy control subjects (n = 84), all of whom were assessed at two time points, 3 years apart. The MCI at baseline in this group was judged to be vascular in etiology (vaMCI). Incident dementia was diagnosed in 24.4% of vaMCI and 8.5% of NCI subjects and no control subjects over 3 years, giving a rate of conversion of approximately 8% per year in post-stroke vaMCI. The vaMCI group showed greater decline in logical memory than the NCI group. Within the vaMCI group, those who developed dementia had great decline in language and executive function. Compared with NCI patients, those with vaMCI had more vascular risk factors and more white matter hyperintensities on MRI at baseline, but did not differ in their brain or hippocampal volumes. Neither MRI volumetric measures nor interval cerebrovascular events predicted decline in function. The major determinant of decline and categorical transition was impaired performance at baseline, suggesting that those with mild impairment post-stroke are more vulnerable to subsequent decline.

Progression of mild cognitive impairment to dementia in clinic- vs community-based cohorts

BACKGROUND

Mild cognitive impairment is increasingly recognized as an important public health problem associated with increased risk of developing dementia. Annual conversion rates, however, vary across different studies with clinic samples showing higher rates of conversion than community-based samples.

OBJECTIVES

To establish whether the rates of conversion from mild cognitive impairment to dementia differed according to recruitment source and, if so, to investigate factors that might explain this discrepancy.

DESIGN

Rates and predictors of conversion were examined in a prospective longitudinal study at a single center.

SETTING

Among the participants, 46% were recruited from a clinical setting and 54% were recruited directly through community outreach.

PARTICIPANTS

One hundred eleven individuals with mild cognitive impairment were followed up longitudinally for an average of 2.4 years (range, 0.5-4.0 years).

MAIN OUTCOME MEASURES

Conversion from mild cognitive impairment to dementia.

RESULTS

During the follow-up period, 28 individuals progressed to dementia with a mean (SD) time to conversion of 2.19 (0.72) years. The clinic sample had an annual conversion rate of 13%, whereas the community sample had an annual conversion rate of 3%. In a Cox proportional hazards model, clinic recruitment source alone was associated with an increased hazard of incident dementia (hazard ratio = 3.50; 95% confidence interval, 1.31-9.18; P = .01). When other variables were added to the model, only baseline functional impairment as measured by the Clinical Dementia Rating Scale (and no demographic, cognitive, or neuroimaging variables or mild cognitive impairment subtype) accounted for the differences in conversion rates across the 2 cohorts.

CONCLUSIONS

These findings add to the growing literature to suggest that the degree of functional impairment at baseline is an important predictor of conversion to dementia and may help explain differences in findings between epidemiological and clinic-based studies.

Structural neuroimaging in Altheimer's disease: do white matter hyperintensities matter?

The targeted brain dysfunction that accompanies aging can have a devastating effect on cognitive and intellectual abilities. A significant proportion of older adults experience precipitous cognitive decline that negatively impacts functional activities. Such individuals meet clinical diagnostic criteria for dementia, which is commonly attributed to Alzheimer's disease (AD). Structural neuroimaging, including magnetic resonance imaging (MRI), has contributed significantly to our understanding of the morphological and pathology-related changes that may underlie normal and disease-associated cognitive change in aging. White matter hyperintensities (WMH), which are distributed patches of increased hyperintense signal on T2-weighted MRI, are among the most common structural neuroimaging findings in older adults. In recent years, WMH have emerged as robust radiological correlates of cognitive decline. Studies suggest that WMH distributed in anterior brain regions are related to decline in executive abilities that is typical of normal aging, whereas WMH distributed in more posterior brain regions are common in AD. Although epidemiological, observational, and pathological studies suggest that WMH may be ischemic in origin and caused by consistent or variable hypoperfusion, there is emerging evidence that they may also reflect vascular deposition of (β-amyloid, particularly when they are distributed in posterior areas and are present in patients with AD. Findings from the literature highlight the potential contribution of small-vessel cerebrovascular disease to the pathogenesis of AD, and suggest a mechanistic interaction, but future longitudinal studies using multiple imaging modalities are required to fully understand the complex role of WMH in AD.

Mediterranean diet and mild cognitive impairment

BACKGROUND

Higher adherence to the Mediterranean diet (MeDi) may protect from Alzheimer disease (AD), but its association with mild cognitive impairment (MCI) has not been explored.

OBJECTIVE

To investigate the association between the MeDi and MCI.

DESIGN, SETTING, AND PATIENTS

In a multiethnic community study in New York, we used Cox proportional hazards to investigate the association between adherence to the MeDi (0-9 scale; higher scores indicate higher adherence) and (1) the incidence of MCI and (2) the progression from MCI to AD. All of the models were adjusted for cohort, age, sex, ethnicity, education, APOE genotype, caloric intake, body mass index, and duration between baseline dietary assessment and baseline diagnosis.

MAIN OUTCOME MEASURES

Incidence of MCI and progression from MCI to AD.

RESULTS

There were 1393 cognitively normal participants, 275 of whom developed MCI during a mean (SD) follow-up of 4.5 (2.7) years (range, 0.9-16.4 years). Compared with subjects in the lowest MeDi adherence tertile, subjects in the middle tertile had 17% less risk (hazard ratio [HR] = 0.83; 95% confidence interval [CI], 0.62-1.12; P = .24) of developing MCI and those in the highest tertile had 28% less risk (HR = 0.72; 95% CI, 0.52-1.00; P = .05) of developing MCI (trend HR = 0.85; 95% CI, 0.72-1.00; P for trend = .05). There were 482 subjects with MCI, 106 of whom developed AD during a mean (SD) follow-up of 4.3 (2.7) years (range, 1.0-13.8 years). Compared with subjects in the lowest MeDi adherence tertile, subjects in the middle tertile had 45% less risk (HR = 0.55; 95% CI, 0.34-0.90; P = .01) of developing AD and those in the highest tertile had 48% less risk (HR = 0.52; 95% CI, 0.30-0.91; P = .02) of developing AD (trend HR = 0.71; 95% CI, 0.53-0.95; P for trend = .02).

CONCLUSIONS

Higher adherence to the MeDi is associated with a trend for reduced risk of developing MCI and with reduced risk of MCI conversion to AD.

Progression of mild cognitive impairment to dementia: contribution of cerebrovascular disease compared with medial temporal lobe atrophy

BACKGROUND AND PURPOSE

We sought to determine the predictive value of magnetic resonance imaging measures of vascular disease (white matter hyperintensities [WMHs], lacunes, microbleeds, and infarcts) compared with atrophy on the progression of mild cognitive impairment to dementia.

METHODS

We included 152 consecutive patients with mild cognitive impairment. Baseline magnetic resonance imaging was used to determine the presence of medial temporal lobe atrophy and vascular disease (presence of lacunes, microbleeds, and infarcts was determined, and WMHs were rated on a semiquantitative scale). Patients were followed up for 2+/-1 years.

RESULTS

Seventy-two (47%) patients progressed to dementia during follow-up. Of these, 56 (37%) patients were diagnosed with Alzheimer's disease, and 16 (10%) patients were diagnosed with a non-Alzheimer dementia (including vascular dementia, frontotemporal lobar degeneration, and Parkinson dementia). Converters were older and had a lower Mini-Mental State Examination score at baseline. On baseline magnetic resonance imaging, patients who progressed to a non-Alzheimer dementia showed more severe WMHs and had a higher prevalence of lacunes in the basal ganglia and microbleeds compared with nonconverters. Cox proportional-hazard models showed that, adjusted for age and sex, baseline medial temporal lobe atrophy (hazard ratio=2.9; 95% CI, 1.7 to 5.3), but not vascular disease, was associated with progression to Alzheimer's disease. By contrast, deep WMHs (hazard ratio=5.7; 95% CI, 1.2 to 26.7) and periventricular hyperintensities (hazard ratio=6.5; 95% CI, 1.4 to 29.8) predicted progression to non-Alzheimer dementia. Furthermore, microbleeds (hazard ratio=2.6; 95% CI, 0.9 to 7.5) yielded a >2-fold increased, though nonsignificant, risk of non-Alzheimer dementia.

CONCLUSIONS

Medial temporal lobe atrophy and markers of cerebrovascular disease predict the development of different types of dementia in mild cognitive impairment patients.

Preventing neurocognitive late effects in childhood cancer survivors

Neurocognitive late effects are common sequelae of cancer in children, especially in those who have undergone treatment for brain tumors or in those receiving prophylactic cranial radiation therapy to treat leukemia. Neurocognitive morbidity in attention, executive functioning, processing speed, working memory, and memory frequently occurs and contributes to declines in intellectual and academic abilities. Oncologists are faced with the challenge of using the most effective, often the most intense, therapy to achieve the primary goal of medical success, balanced with the desire to prevent adverse late effects. Not all children with similar diagnoses and treatment have identical neurocognitive outcomes; some do very poorly and some do well. Attention now turns to the reliable prediction of risk for poor outcomes and then, using risk-adapted therapy, to preserve neurocognitive function. Prevention of late effects through rehabilitative strategies, continuation of school, and pharmacotherapy will be explored.

Periventricular white matter hyperintensities increase the likelihood of progression from amnestic mild cognitive impairment to dementia

BACKGROUND

White matter hyperintensities (WMH) have an effect on cognition and are increased in severity among individuals with amnestic mild cognitive impairment (aMCI). The influence of WMH on progression of aMCI to Alzheimer's disease (AD) is less clear.

METHODS

Data were drawn from a three-year prospective, double blind, placebo controlled clinical trial that examined the effect of donepezil or vitamin E on progression from aMCI to AD. WMH from multiple brain regions were scored on MR images obtained at entry into the trial from a subset of 152 study participants using a standardized visual rating scale. Cox proportional hazards models adjusting for age, education and treatment arm were used to investigate the role of WMH on time to progression.

RESULTS

55 of the 152 (36.2 %) aMCI subjects progressed to AD. Only periventricular hyperintensities (PVH) were related to an increased risk of AD within three years (HR = 1.59, 95 % CI = 1.24 - 2.05, p-value < 0.001). Correcting for medial temporal lobe atrophy or the presence of lacunes did not change statistical significance.

CONCLUSION

PVH are associated with an increased risk of progression from aMCI to AD. This suggests that PVH, an MRI finding thought to represent cerebrovascular damage, contributes to AD onset in vulnerable individuals independent of Alzheimer pathology.

Is computed tomography still useful as a neuroimaging tool in psychiatry?

BACKGROUND

Computed tomography (CT) has played a pivotal role in psychiatry from its inception; however with the advent of other high-resolution noninvasive neuroimaging techniques such as MRI, the field has gone through a dramatic transformation.

OBJECTIVE

This article will explore the current role of CT in psychiatry.

METHODS

An extensive search of the published literature (1970 - 2008) was conducted, employing a number of databases and terms relevant to CT and imaging.

RESULTS/CONCLUSION

At present CT is primarily used as a screening tool to exclude intracranial pathology. This is partly because it is widely available and less expensive than other imaging modalities. CT is unable to provide region-specific information like MRI and this has restricted its use in disorders in which functional disturbances are suspected, however it remains the preferred mode of investigation where gross structural abnormalities are suspected.

Memory and cognition in preclinical dementia: what we know and what we do not know

This overview focuses on the cognitive transition between normal aging and dementia. Numerous studies indicate that individuals who will go on to develop dementia show cognitive deficits many years before the time at which a clinical diagnosis could be rendered. The degree of preclinical impairment is remarkably similar for tasks assessing episodic memory, executive functioning, and perceptual speed, consistent with the view that multiple brain alterations occur prior to clinical disease onset. Although most research in this area has dealt with Alzheimer disease (AD), several recent reports indicate that the pattern of preclinical impairment is very similar in the second largest dementia disorder, vascular dementia (VaD). This is important because currently the possibility for interventions to postpone disease onset is greater in VaD than in AD. Despite pronounced preclinical cognitive deficits in dementia, the performance distributions between cases and controls are largely overlapping, hampering the ability to identify high-risk individuals. To alleviate this problem, future research should evaluate hybrid models for the prediction of dementia. In such models, multiple indicators of cognitive functioning should be included along with markers from other domains that have been linked to subsequent dementia (such as brain imaging, genetics, and lifestyle variables). To the extent that these categories of variables add unique variance, classification accuracy will increase and the overlap in performance scores between incident cases and controls will decrease, thereby enhancing clinical usefulness. This approach would also facilitate the examination of interactive effects among classes of preclinical markers.

Vascular subcortical hyperintensities predict conversion to vascular and mixed dementia in MCI patients

BACKGROUND AND PURPOSE

Patients with mild cognitive impairment (MCI) have an increased risk of dementia. The identification of predictors of conversion to dementia is therefore important. The aim of our study was to test the hypothesis that subcortical hyperintensities (SH) are associated with an increased rate of conversion to dementia in MCI patients.

METHODS

This was an observational study on consecutive MCI patients attending a memory clinic. We assessed SH on a baseline MRI scan, using a semiquantitative rating scale. A multivariable Cox regression model was used to test the association of SH with conversion to dementia.

RESULTS

We included 170 MCI patients. The median duration of follow-up was 3.8 years. During this period, 67 patients (39.4%, 95% CI: 32.1 to 46.8%) developed dementia: Alzheimer disease (AD) in 29 patients, dementia with Lewy bodies in 19, mixed dementia in 8, vascular dementia in 7, fronto-temporal dementia in 2, and primary progressive aphasia in 2. SH were not associated with the risk to develop dementia as a whole, including AD. However, the risk to develop vascular or mixed dementia increased significantly with increasing amounts of SH at baseline (HR=1.14 [95% CI: 1.06 to 1.24]), especially periventricular hyperintensities (HR=2.71 [95% CI: 1.60 to 4.58]), independently of medial temporal lobe atrophy, age, gender, vascular risk factors, education, and cognitive functions at baseline.

CONCLUSIONS

The risk of vascular or mixed dementia, but not of other types of dementia, was significantly increased in MCI patients with a large amount of subcortical hyperintensities at baseline.

Subcortical ischemic vascular disease and cognition: A systematic review

Subcortical Ischemic Vascular Disease (SIVD) is underdiagnosed. This review investigates the relationship among SIVD severity, cognitive status and neuroimaging markers.

METHODS

Cohort, cross-sectional and case control studies were searched on ISI, Medline, Scielo, PsychoInfo and LILACS databases published between 1995 and 2006.

RESULTS

The most impaired cognitive domains were executive, attentional and memory retrieval mechanisms. These cognitive features were frequently associated to White Matter Lesions (WML).

CONCLUSIONS

WML is an independent factor in cognitive decline. However, the threshold for this impact is not yet clearly established.

The cerebrovascular pathology in Alzheimer's disease and its influence on clinical variables

Vascular pathology is frequently found in the brains of patients with Alzheimer's disease (AD). The aim of this study is to assess the frequency of vascular pathology in the brain in AD patients in a systematic manner and its clinical significance at presentation. A series of 51 patients with mild to moderate AD were consecutively enrolled. At baseline, every patient underwent the following clinical scales: Mini-Mental, Clinical Dementia Rating Scale, Ischemic Scale, Blessed Dementia Rating Scale, Alzheimer's Disease Assessment Scale Cognitive Subscale, Neuropsychiatric Inventory, and an Activities of Daily Living Scale (Disability Assessment for Dementia). We also carried out magnetic resonance imaging of the brain and color echo Doppler of carotids to measure the intima-media thickness. White matter hyperintensities were quantitatively evaluated with the Wahlund scale. We did not find correlation between intima-media thicknesses of carotids and clinical scales and between the Wahlund scale and clinical scales. The presence or absence of both microinfarctions and hypertension had no influence in the scores of the clinical scales. We conclude that the vascular component is common in AD but only as coincident pathology.

Subcortical hyperintensities are associated with cognitive decline in patients with mild cognitive impairment

BACKGROUND AND PURPOSE

It has been suggested that subcortical lesions may influence cognitive performances at early stages of cognitive impairment but not in late stages of dementia. We aimed to test whether cognitive decline is associated with subcortical hyperintensities in patients with mild cognitive impairment (MCI).

METHODS

We included 170 consecutive MCI patients (mean follow-up, 3.8+/-1.6 years). We assessed subcortical hyperintensities on a baseline magnetic resonance imaging scan with a semiquantitative rating scale. The mean annual cognitive decline was calculated with the Mini-Mental State Examination and the Dementia Rating Scale at baseline and the end of follow-up.

RESULTS

Compared with patients whose cognitive performances remained stable or improved during follow-up, patients whose cognitive performances declined often had a larger amount (greater than the median of the distribution) of periventricular (PVH) (P=0.0005) and white-matter (P=0.02) hyperintensities. The rate of cognitive decline was higher with increasing PVH: mean change in the Mini-Mental State Examination score=0.16 vs -0.66 points/year in patients with PVH in the first versus third tertile (P=0.0002). The rate of decline in executive functioning was also higher with increasing PVH: mean change in the Dementia Rating Scale initiation subscore=-0.05 vs -1.42 points/year in patients with PVH in the first versus third tertile (P=0.04). These associations were independent of vascular risk factors, temporal lobe atrophy, and MCI subtype and were stronger in patients with baseline executive dysfunction.

CONCLUSIONS

White-matter hyperintensities and especially PVH were significantly associated with cognitive decline in MCI patients. This result was independent of the MCI subtype but stronger in cases of executive dysfunction at baseline.

Vascular risk factors and white matter hyperintensities in patients with amnestic mild cognitive impairment

BACKGROUND

Subjects affected by aMCI are considered at high risk for AD. Nevertheless, the role of both vascular risk factors and WMH is matter of debate.

PATIENTS AND METHODS

We enrolled consecutively 21 aMCI subjects according to Petersen Criteria; the study included routine screening for dementia, neuropsychological evaluation and brain MRI. Six vascular risk factors were assessed and WMH was quantified by means of a semiautomatic lesion-detection program.

RESULTS

Conversion to AD, according to NINCDS-ADRDA criteria, was 47.6%. Converters tended to be more affected by the most of vascular risk factors while no difference was noted in WMH. The best predictors of conversion to AD were scores obtained at several neuropsychological examination.

CONCLUSION

Our results show that criteria for aMCI identify subjects with a high risk to develop AD. WMH doesn't seem to have a role in progression from aMCI to AD, while some vascular risk factors seem to promote it.

Neuroimaging of white matter in aging and dementia

Clinical neuroscientists have focused increasing attention on white matter connections in the brain and on the effects of aging and disease on these connections. Recent advances in magnetic resonance imaging (MRI) analysis have given researchers new tools for quantifying and visualizing white matter to better relate white matter structure and function. The goals of this article are (a) to acquaint the reader with both established and newer methods for imaging and quantifying white matter anatomy and pathology; and (b) to review recent findings on white matter pathology in aging and dementia. Computer-assisted quantification appears to offer better statistical power than visual rating scales for detecting these relationships. New MR modalities such as diffusion imaging can detect white matter abnormalities not shown with conventional acquisition sequences. These newer techniques hold promise for early detection of disease and for delineating functional connections between brain areas.