Mental calculation in mild Alzheimer's disease: A pilot study

The purpose of this study was to determine whether dyscalculia is present in the early stages of Alzheimer's disease (AD) and if it is associated with a characteristic neuropsychological pattern. We examined 28 probable AD patients with scores of 18 or greater on the Mini-Mental State Examination (MMS) and with an educational level of 12 or more years. The ability to perform mental calculation was assessed by two tests: the Stamp Test (ST) and the Serial Seven Subtraction Test (SSST). The other cognitive domains were evaluated with an extensive neuropsychological battery. We found significant differences in performances on the calculation tests between patients and controls. The ST was correlated with attention and visuospatial skills, whereas the SSST was correlated with both receptive language and the MMS; both test were similarly correlated with productive language. This study suggests that impairment in mental calculation can be an early sign of AD. The ST seems to represent a more complex task dependent on attentional resources, whereas the SSST would be a purer measure of anarithmetia.     

Syndromes of behavioural and psychological symptoms in mild Alzheimer's disease

OBJECTIVES: Behavioural and psychological symptoms of dementia (BPSD) are common in Alzheimer's disease (AD), and are associated with significant distress for patient and carer. Certain behavioural and psychological symptoms have been associated with each other, leading to the suggestion that differences in symptom patterns among patients with AD may represent different syndromes within AD. The purpose of this study is to see if patients with AD could be meaningfully classified into syndromes, based on the relationships between their BPSD. METHODOLOGY: The sample was recruited through a memory clinic. Two hundred and forty first visit patients with a diagnosis of very mild to mild AD were included. BPSD were assessed using the BEHAVE-AD. Latent class analysis was used to assess for different classes or groups of patients within the sample, based on their behavioural and psychological symptoms. RESULTS: Three classes were identified; Class 1 with a low prevalence of behavioural and psychological symptoms; Class 2 an anxiety/depressive symptom class and Class 3 an aggressive symptom class. CONCLUSIONS: The three classes (or groups) of patients obtained by LCA in this sample may be explained by a 'latent', as yet, unidentified factor. Further research is required to determine if these classes are stable over time, and to identify possible latent variables.     

Subjective rating of executive functions in mild Alzheimer's disease

Objectives: Subjective cognitive decline is considered to be a core feature of pre-Alzheimer's disease (AD) conditions, the vast majority of literature having focused on memory concerns. Neuropsychological studies have implicated executive dysfunction on objective performance measures in AD, but no research has evaluated whether individuals with AD have concerns about their executive functions and whether it differs from their caregiver's concerns. In the present study, we sought to evaluate self- and informant ratings of executive functioning in patients with mild AD.

Method: Participants were 23 patients with mild AD and 32 healthy elderly controls (HC) and their informants who completed the Behavior Rating Inventory of Executive Function – Adult version.

Results: Patients with AD and their informants reported greater executive dysfunction than the HC group and their informants, respectively, and patients reported greater difficulty than their informants. The largest effect size for both self- and informant ratings was obtained for the Working Memory scale.

Conclusions: These findings indicate that subjective cognitive concerns in mild AD extend beyond the memory domain to executive functions. That greater difficulty was endorsed by patients than their informants suggests that at least in the mild stage of AD some awareness of executive dysfunction may be maintained in some patients. Implications for clinical care are discussed.     

Hippocampal atrophy patterns in mild cognitive impairment and Alzheimer's disease

Background:

Histopathological studies and animal models suggest that hippocampal subfields may be differently affected by aging, Alzheimer's disease (AD), and other diseases. High‐resolution images at 4 Tesla depict details of the internal structure of the hippocampus allowing for in vivo volumetry of different subfields. The aims of this study were as follows: (1) to determine patterns of volume loss in hippocampal subfields in normal aging, AD, and amnestic mild cognitive impairment (MCI). (2) To determine if measurements of hippocampal subfields provide advantages over total hippocampal volume for differentiation between groups.

Methods:

Ninety‐one subjects (53 controls (mean age: 69.3 ± 7.3), 20 MCI (mean age: 73.6 ± 7.1), and 18 AD (mean age: 69.1 ± 9.5) were studied with a high‐resolution T2 weighted imaging sequence aimed at the hippocampus. Entorhinal cortex (ERC), subiculum, CA1, CA1‐CA2 transition zone (CA1‐2), CA3 & dentate gyrus (CA3&DG) were manually marked in the anterior third of the hippocampal body. Hippocampal volume was obtained from the Freesurfer and manually edited.

Results:

Compared to controls, AD had smaller volumes of ERC, subiculum, CA1, CA1‐2, and total hippocampal volumes. MCI had smaller CA1‐2 volumes. Discriminant analysis and power analysis showed that CA1‐2 was superior to total hippocampal volume for distinction between controls and MCI.

Conclusion:

The patterns of subfield atrophy in AD and MCI were consistent with patterns of neuronal cell loss/reduced synaptic density described by histopathology. These preliminary findings suggest that hippocampal subfield volumetry might be a better measure for diagnosis of early AD and for detection of other disease effects than measurement of total hippocampus. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.

     

Altered resting state networks in mild cognitive impairment and mild Alzheimer's disease: an fMRI study

Activity and reactivity of the default mode network in the brain was studied using functional magnetic resonance imaging (fMRI) in 28 nondemented individuals with mild cognitive impairment (MCI), 18 patients with mild Alzheimer's disease (AD), and 41 healthy elderly controls (HC). The default mode network was interrogated by means of decreases in brain activity, termed deactivations, during a visual encoding task and during a nonspatial working memory task. Deactivation was found in the default mode network involving the anterior frontal, precuneus, and posterior cingulate cortex. MCI patients showed less deactivation than HC, but more than AD. The most pronounced differences between MCI, HC, and AD occurred in the very early phase of deactivation, reflecting the reactivity and adaptation of the network. The default mode network response in the anterior frontal cortex significantly distinguished MCI from both HC (in the medial frontal) and AD (in the anterior cingulate cortex). The response in the precuneus could only distinguish between patients and HC, not between MCI and AD. These findings may be consistent with the notion that MCI is a transitional state between healthy aging and dementia and with the proposed early changes in MCI in the posterior cingulate cortex and precuneus. These findings suggest that altered activity in the default mode network may act as an early marker for AD pathology.     

Structural MRI biomarkers for preclinical and mild Alzheimer's disease

Noninvasive MRI biomarkers for Alzheimer's disease (AD) may enable earlier clinical diagnosis and the monitoring of therapeutic effectiveness. To assess potential neuroimaging biomarkers, the Alzheimer's Disease Neuroimaging Initiative is following normal controls (NC) and individuals with mild cognitive impairment (MCI) or AD. We applied high‐throughput image analyses procedures to these data to demonstrate the feasibility of detecting subtle structural changes in prodromal AD. Raw DICOM scans (139 NC, 175 MCI, and 84 AD) were downloaded for analysis. Volumetric segmentation and cortical surface reconstruction produced continuous cortical surface maps and region‐of‐interest (ROI) measures. The MCI cohort was subdivided into single‐ (SMCI) and multiple‐domain MCI (MMCI) based on neuropsychological performance. Repeated measures analyses of covariance were used to examine group and hemispheric effects while controlling for age, sex, and, for volumetric measures, intracranial vault. ROI analyses showed group differences for ventricular, temporal, posterior and rostral anterior cingulate, posterior parietal, and frontal regions. SMCI and NC differed within temporal, rostral posterior cingulate, inferior parietal, precuneus, and caudal midfrontal regions. With MMCI and AD, greater differences were evident in these regions and additional frontal and retrosplenial cortices; evidence for non‐AD pathology in MMCI also was suggested. Mesial temporal right‐dominant asymmetries were evident and did not interact with diagnosis. Our findings demonstrate that high‐throughput methods provide numerous measures to detect subtle effects of prodromal AD, suggesting early and later stages of the preclinical state in this cross‐sectional sample. These methods will enable a more complete longitudinal characterization and allow us to identify changes that are predictive of conversion to AD. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.     

Cerebrospinal fluid biomarkers of neurovascular dysfunction in mild dementia and Alzheimer's disease

Alzheimer''s disease (AD) is the most common form of age-related dementias. In addition to genetics, environment, and lifestyle, growing evidence supports vascular contributions to dementias including dementia because of AD. Alzheimer''s disease affects multiple cell types within the neurovascular unit (NVU), including brain vascular cells (endothelial cells, pericytes, and vascular smooth muscle cells), glial cells (astrocytes and microglia), and neurons. Thus, identifying and integrating biomarkers of the NVU cell-specific responses and injury with established AD biomarkers, amyloid-β (Aβ) and tau, has a potential to contribute to better understanding of the disease process in dementias including AD. Here, we discuss the existing literature on cerebrospinal fluid biomarkers of the NVU cell-specific responses during early stages of dementia and AD. We suggest that the clinical usefulness of established AD biomarkers, Aβ and tau, could be further improved by developing an algorithm that will incorporate biomarkers of the NVU cell-specific responses and injury. Such biomarker algorithm could aid in early detection and intervention as well as identify novel treatment targets to delay disease onset, slow progression, and/or prevent AD.     

Subjective memory complaints in Chinese subjects with mild cognitive impairment and early Alzheimer's disease

BACKGROUND: Mild cognitive impairment (MCI) represents a transitional state between normal aging and dementia. However, there is inconsistent opinion as to the validity of subjective memory complaints as a criterion for diagnosis. OBJECTIVE: This study aimed to examine the potential significance of applying a short memory questionnaire in the assessment of Chinese subjects with MCI and early dementia. METHODS: Three hundred and six ambulatory Chinese subjects were recruited. Each participant completed a short memory questionnaire. They were also assessed with the Chinese versions of the mini-mental state examination (CMMSE), Alzheimer's disease assessment scale-cognitive subscale (ADAS-Cog), category verbal fluency test (CVFT) and span tests. Severity of cognitive impairment was evaluated using the Clinical Dementia Rating (CDR); subjects with CDR 0.5 were further classified into MCI not demented (MCIND) and MCI possible incipient dementia (MCIID) depending on the subscale scores of CDR. RESULTS: An increasing frequency of memory complaints with increasing CDR was observed (Kruskal Wallis test, chi square = 21.29, df 3, p < 0.001). With a cutoff of 3 or more memory complaints, the memory questionnaire demonstrated a sensitivity of 65.3% and 70.4% in identifying subjects with incipient and early dementia respectively. Significant associations between memory complaints and most cognitive test performance were found (Spearman's correlations, p < 0.01). Logistic regression analysis revealed that educational level, the memory questionnaire, ADAS-Cog total and delayed recall scores were significant predictors of MCIID status. CONCLUSIONS: The findings suggested that a short memory questionnaire is useful in the screening of MCI, particularly in subjects who already present with subtle functioning disturbances. Subjective memory complaints were significant correlated with objective performance of memory functions, reflecting the usefulness of memory complaints in the assessment of MCI.     

Olanzapine does not enhance cognition in non-agitated and non-psychotic patients with mild to moderate Alzheimer's dementia

OBJECTIVE: This was an exploratory study of olanzapine as potential treatment for improvement in cognition in patients with Alzheimer's disease without prominent psychobehavioral symptoms. METHODS: Non-psychotic/non-agitated patients (n = 268) with Alzheimer's disease, who had baseline Mini-Mental State Examination (MMSE) scores of 14-26 were randomized to treatment with olanzapine (2.5 to 7.5 mg/d) or placebo for 26 weeks. The primary objectives were to determine if treatment with olanzapine improved cognition as indexed by the Alzheimer's disease Assessment Scale for Cognition (ADAS-Cog) and the Clinician's Interview-Based Impression of Change (CIBIC) after 26 weeks of therapy. RESULTS: Patients treated with olanzapine vs placebo experienced significant worsening ADAS-Cog scores at weeks 12 (p = 0.03) and 26 (p = 0.004). Changes in CIBIC scores were not significantly different between treatment groups at either assessment. A post hoc analysis revealed that olanzapine-treated patients with more cognitive impairment at baseline (MMSE scores of 14-18) (n = 35) experienced significantly greater deterioration in ADAS-Cog performance than patients in the placebo group (n = 24; p < 0.001); whereas in patients with less cognitive impairment (n = 78, baseline MMSE scores of 23-26) between-group ADAS-Cog changes were not significant. CONCLUSIONS: In this 26-week study non-psychotic/non-agitated patients with Alzheimer's disease treated with olanzapine experienced significant worsening of cognition as compared to placebo.     

The validity and reliability of the Turkish version of Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) in patients with mild and moderate Alzheimer's disease and normal subjects

OBJECTIVES: The cognitive subscale of the Alzheimer's Disease Assesment Scale (ADAS-Cog) is the most widely used test in clinical trials dealing with Alzheimer's disease (AD). The aim of this study was to investigate the validity and reliability of the Turkish version of ADAS-Cog. METHODS: Twenty-nine patients with AD, fulfilling NINCDS-ADRDA criteria of probable AD, who were in stage 3-5 according to the Global Deterioration Scale (GDS), and 27 non-demented control subjects with similar age, gender and educational status were recruited for the study. The Turkish version of ADAS-Cog, Standardized Mini Mental Status Examination (MMSE) and Short Orientation-Memory-Concentration Test (SOMCT) were applied to both of the groups. Inter-rater reliability, internal consistency, test-retest reliability; face validity, differential validity and convergent validity were statistically analyzed. RESULTS: Both MMSE and ADAS-Cog have significantly differentiated patients with AD and control subjects (p < 0.001). A significant correlation was established between MMSE and ADAS-Cog scores in AD group (r: -0.739). ADAS-Cog was also highly significantly correlated with GDS (r: 0.720) and SOMCT (r: 0.738). For the group with AD, control and whole cohort coefficients of internal consistency, Cronbach's alpha: 0.800, 0.515, 0.873 were found respectively. Inter-rater reliability for total ADAS-Cog score was found as ICC: 0.99 and 0.98 and test-retest reliability was found as ICC: 0.91 and 0.95 for demented and nondemented subjects, respectively. CONCLUSION: The Turkish version of ADAS-Cog has been found to be highly reliable and valid in differentiating patients with mild and moderate AD from nondemented subjects.