Mild Probable Alzheimer's Disease Research Articles

Combining neuropsychological assessment and structural neuroimaging to identify early Alzheimer's disease in a memory clinic cohort.

The current study examined the contributions of comprehensive neuropsychological assessment and volumetric assessment of selected mesial temporal subregions on structural magnetic resonance imaging (MRI) to identify patients with amnestic mild cognitive impairment (aMCI) and mild probable Alzheimer's disease (AD) dementia in a memory clinic cohort. Comprehensive neuropsychological assessment and automated entorhinal, transentorhinal, and hippocampal volume measurements were conducted in 40 healthy controls, 38 patients with subjective memory symptoms, 16 patients with aMCI, 16 patients with mild probable AD dementia. Multinomial logistic regression was used to compare the neuropsychological and MRI measures. Combining the neuropsychological and MRI measures improved group membership prediction over the MRI measures alone but did not improve group membership prediction over the neuropsychological measures alone. Comprehensive neuropsychological assessment was an important tool to evaluate cognitive impairment. The mesial temporal volumetric MRI measures contributed no diagnostic value over and above the determinations made through neuropsychological assessment.

Episodic Thinking in Alzheimer's Disease Through the Lens of Language: Linguistic Analysis and Transformer-Based Classification.

Episodic memory decline is a hallmark of Alzheimer's disease (AD) and linked to deficits in episodic thinking directed to the future. We addressed the question whether a deficit in episodic thinking can be picked up directly from connected speech and its detection can be automatized. We linguistically classified 2,809 utterances (including embedded clauses in the utterances) from picture descriptions from 70 healthy older controls, 82 people with mild probable AD (pAD), and 46 people with moderate pAD for whether they were episodic, nonepisodic, or "other" (e.g., off-task). Generalized linear regression models were used to investigate how ratios of these categories change in AD, controlling for age, gender, and education. Finally, we applied deep learning technique to explore the feasibility of automating the episodicity analysis. Decline in episodicity significantly distinguished controls from both mild pAD and moderate pAD. Correlation analysis suggested this decline not to be an effect of age, gender, and education but of cognitive ability. The decline was not compensated by an increase of nonepisodic utterances but mainly of off-task expressions. A transformer-based classifier to explore the possibility of automatizing the classification of episodicity achieved a macro F1 score of 0.913 in the ternary classification. These results show that a loss of episodicity is an early effect in AD that is manifested in spontaneous speech and can be reliably measured by both humans and machines.

Volumetric regional MRI and neuropsychological predictors of motor task variability in cognitively unimpaired, Mild Cognitive Impairment, and probable Alzheimer's disease older adults

IntroductionThe mechanisms linking motor function to Alzheimer's disease (AD) progression have not been well studied, despite evidence of AD pathology within motor brain regions. Thus, there is a need for new motor measure that is sensitive and specific to AD. MethodsIn a sample of 121 older adults (54 cognitive unimpaired [CU], 35 amnestic Mild Cognitive Impairment [aMCI], and 32 probable mild AD), intrasubject standard deviation (ISD) across six trials of a novel upper-extremity motor task was predicted with volumetric regional gray matter and neuropsychological scores using classification and regression tree (CART) analyses. ResultsBoth gray matter and neuropsychological CART models indicated that motor task ISD (our measure of motor learning) was related to cortical regions and cognitive test scores associated with memory, executive function, and visuospatial skills. CART models also accurately distinguished motor task ISD of MCI and probable mild AD from CU. DiscussionVariability in motor task performance across practice trials may be valuable for understanding preclinical and early-stage AD.

Olive polyphenols and bioavailable glutathione: Promising results in patients diagnosed with mild Alzheimer's disease.

IntroductionRecent studies highlighted the role of olive polyphenols in disrupting the ordered structure of highly cytotoxic amyloid beta protofibrils and the efficacy of a derivatized form of glutathione to counteract neuronal oxidative stress affecting specific brain regions at early stages of Alzheimer's disease (AD) pathogenesis. We performed a randomized cross‐over clinical trial to evaluate their potential benefits in mild AD.MethodsOleuropein and S‐acetyl glutathione were administered as dietary supplement for 6 months to 18 patients diagnosed for probable mild AD according to International Working Group 2 criteria. Patients underwent an extensive cognitive and behavioral neuropsychological test battery at the beginning and end of the study to evaluate cognitive deterioration, memory, visuospatial abilities, attention, language, executive functions, and behavioral disorders. We compared patients receiving treatment to patients receiving no treatment.ResultsAll the measured neurocognitive parameters stabilized or improved after the treatment in all patients.DiscussionDietary supplement with olive polyphenols and bioavailable glutathione could be useful for patients diagnosed with mild AD.

Effect of APOE Genotype on Plasma Docosahexaenoic Acid (DHA), Eicosapentaenoic Acid, Arachidonic Acid, and Hippocampal Volume in the Alzheimer's Disease Cooperative Study-Sponsored DHA Clinical Trial.

Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) play key roles in several metabolic processes relevant to Alzheimer's disease (AD) pathogenesis and neuroinflammation. Carrying the APOEɛ4 allele (APOE4) accelerates omega-3 polyunsaturated fatty acid (PUFA) oxidation. In a pre-planned subgroup analysis of the Alzheimer's Disease Cooperative Study-sponsored DHA clinical trial, APOE4 carriers with mild probable AD had no improvements in cognitive outcomes compared to placebo, while APOE 4 non-carriers showed a benefit from DHA supplementation. We sought to clarify the effect of APOEɛ4/ɛ4 on both the ratio of plasma DHA and EPA to AA, and on hippocampal volumes after DHA supplementation. Plasma fatty acids and APOE genotype were obtained in 275 participants randomized to 18 months of DHA supplementation or placebo. A subset of these participants completed brain MRI imaging (n = 86) and lumbar punctures (n = 53). After the intervention, DHA-treated APOEɛ3/ɛ3 and APOEɛ2/ɛ3 carriers demonstrated significantly greater increase in plasma DHA/AA compared to ɛ4/ɛ4 carriers. APOEɛ2/ɛ3 had a greater increase in plasma EPA/AA and less decline in left and right hippocampal volumes compared to compared to ɛ4/ɛ4 carriers. The change in plasma and cerebrospinal fluid DHA/AA was strongly correlated. Greater baseline and increase in plasma EPA/AA was associated with a lower decrease in the right hippocampal volume, but only in APOE 4 non-carriers. The lower increase in plasma DHA/AA and EPA/AA in APOEɛ4/ɛ4 carriers after DHA supplementation reduces brain delivery and affects the efficacy of DHA supplementation.

Brain PET amyloid and neurodegeneration biomarkers in the context of the 2018 NIA-AA research framework: an individual approach exploring clinical-biomarker mismatches and sociodemographic parameters.

[18F]FDG-PET and [11C]PIB-PET are validated as neurodegeneration and amyloid biomarkers of Alzheimer's disease (AD). We used a PET staging system based on the 2018 NIA-AA research framework to compare the proportion of amyloid positivity (A+) and hypometabolism ((N)+) in cases of mild probable AD, amnestic mild cognitive impairment (aMCI), and healthy controls, incorporating an additional classification of abnormal [18F]FDG-PET patterns and investigating the co-occurrence of such with A+, exploring [18F]FDG-PET to generate hypotheses in cases presenting with clinical-biomarker "mismatches." Elderly individuals (N = 108) clinically classified as controls (N = 27), aMCI (N = 43) or mild probable AD (N = 38) were included. Authors assessed their A(N) profiles and classified [18F]FDG-PET neurodegenerative patterns as typical or non-typical of AD, performing re-assessments of images whenever clinical classification was in disagreement with the PET staging (clinical-biomarker "mismatches"). We also investigated associations between "mismatches" and sociodemographic and educational characteristics. AD presented with higher rates of A+ and (N)+. There was also a higher proportion of A+ and (N)+ individuals in the aMCI group in comparison to controls, however without statistical significance regarding the A staging. There was a significant association between amyloid positivity and AD (N)+ hypometabolic patterns typical of AD. Non-AD (N)+ hypometabolism was seen in all A- (N)+ cases in the mild probable AD and control groups and [18F]FDG-PET patterns classified such individuals as "SNAP" and one as probable frontotemporal lobar degeneration. All A- (N)- cases in the probable AD group had less than 4years of formal education and lower socioeconomic status (SES). The PET-based staging system unveiled significant A(N) differences between AD and the other groups, whereas aMCI and controls had different (N) staging, explaining the cognitive impairment in aMCI. [18F]FDG-PET could be used beyond simple (N) staging, since it provided alternative hypotheses to cases with clinical-biomarker "mismatches." An AD hypometabolic pattern correlated with amyloid positivity. Low education and SES were related to dementia in the absence of biomarker changes.

Visual Processing during Short-Term Memory Binding in Mild Alzheimer's Disease.

Patients with Alzheimer's disease (AD) typically present with attentional and oculomotor abnormalities that can have an impact on visual processing and associated cognitive functions. Over the last few years, we have witnessed a shift toward the analyses of eye movement behaviors as a means to further our understanding of the pathophysiology of common disorders such as AD. However, little work has been done to unveil the link between eye moment abnormalities and poor performance on cognitive tasks known to be markers for AD patients, such as the short-term memory-binding task. We analyzed eye movement fixation behaviors of thirteen healthy older adults (Controls) and thirteen patients with probable mild AD while they performed the visual short-term memory binding task. The short-term memory binding task asks participants to detect changes across two consecutive arrays of two bicolored object whose features (i.e., colors) have to be remembered separately (i.e., Unbound Colors), or combined within integrated objects (i.e., Bound Colors). Patients with mild AD showed the well-known pattern of selective memory binding impairments. This was accompanied by significant impairments in their eye movements only when they processed Bound Colors. Patients with mild AD remarkably decreased their mean gaze duration during the encoding of color-color bindings. These findings open new windows of research into the pathophysiological mechanisms of memory deficits in AD patients and the link between its phenotypic expressions (i.e., oculomotor and cognitive disorders). We discuss these findings considering current trends regarding clinical assessment, neural correlates, and potential avenues for robust biomarkers.

THE ADDENBROOKE’S COGNITIVE EXAMINATION-REVISED (ACE-R) IN THE DIAGNOSIS OF MILD COGNITIVE IMPAIRMENT DUE TO ALZHEIMER’S DISEASE: A PRELIMINARY ANALYSIS

The ACE-R allows a brief evaluation of five cognitive domains and has proven to be useful in detecting dementia. However, its diagnostic value in mild cognitive impairment (MCI), especially due to Alzheimer's disease (AD), has been much less investigated. The battery also offers the VLOM ratio sub-score that comprises the ratio of the scores of verbal fluency + language / orientation +memory. The test was administered to 19 MCI patients who converted to AD dementia over a three-year follow-up, to 90 probable mild AD dementia and to 98 cognitively healthy subjects, matched for age and education. All subjects were also submitted to the Mattis Dementia Rating Scale. The three groups were compared and cut-off points for ACE-R total score and VLOM ratio were defined by ROC curve analysis. Areas under ROC curves-AUC (cut-off points - % sensitivity / % specificity) for ACE-R were: MCI-AD x controls = 0.755 (<87 - 100.0/45.9), AD dementia x controls = 0.864 (<80 - 77.7/79.6), MCI-AD x AD dementia = 0.738 (<76 - 60.0/84.2). VLOM ratio analysis displayed an AUC = 0.883 (>2.9 - 84.2/81.6) for MCI-AD x controls. The preliminary results confirm good sensitivity of the ACE-R in discriminating MCI-AD from healthy controls, particularly through the VLOM ratio. However, the specificity must be improved. The test also demonstrated good capacity on differentiating mild AD dementia from controls. MCI-AD patients displayed a mean score eight points higher than AD dementia subjects, an information that may be useful in the clinical setting. The inclusion of additional MCI patients will allow to investigate the value of the ACE-R in predicting MCI conversion to dementia, as well as to explore alternative component analysis as a strategy to achieve a better differential diagnosis between MCI-AD from MCI non-converters or from MCI converting into non-AD dementias.

Changes of EEG Spectra and Functional Connectivity during an Object-Location Memory Task in Alzheimer's Disease.

Object-location memory is particularly fragile and specifically impaired in Alzheimer’s disease (AD) patients. Electroencephalogram (EEG) was utilized to objectively measure memory impairment for memory formation correlates of EEG oscillatory activities. We aimed to construct an object-location memory paradigm and explore EEG signs of it. Two groups of 20 probable mild AD patients and 19 healthy older adults were included in a cross-sectional analysis. All subjects took an object-location memory task. EEG recordings performed during object-location memory tasks were compared between the two groups in the two EEG parameters (spectral parameters and phase synchronization). The memory performance of AD patients was worse than that of healthy elderly adults The power of object-location memory of the AD group was significantly higher than the NC group (healthy elderly adults) in the alpha band in the encoding session, and alpha and theta bands in the retrieval session. The channels-pairs the phase lag index value of object-location memory in the AD group was clearly higher than the NC group in the delta, theta, and alpha bands in encoding sessions and delta and theta bands in retrieval sessions. The results provide support for the hypothesis that the AD patients may use compensation mechanisms to remember the items and episode.

Increased long distance event-related gamma band connectivity in Alzheimer's disease.

BackgroundBrain oscillatory responses can be used for non-invasive analyses of cortico-cortical connectivity, local neuronal synchronization, and coherence of oscillations in many neuropsychiatric conditions including Alzheimer's disease (AD). In the present paper, we examine sensory-evoked and event-related gamma coherences elicited by visual stimuli in three sub-gamma bands in two sub-groups of patients with AD (i.e., acetylcholinesterase-inhibitor treated and untreated) and healthy controls.MethodsWe studied a total of 39 patients with probable mild AD (according to NINCDS-ADRDA criteria) who had been sub-divided into untreated (n = 21) and treated (n = 18) (patients either on cholinergic monotherapy or combined therapy with memantine) AD groups, and 21 age-, gender-, and education-matched healthy elderly controls. A simple flash visual paradigm was applied for the acquisition of sensory-evoked coherences. Event-related coherences were elicited using a classical visual oddball paradigm. Both sensory-evoked and event-related gamma coherences were calculated for long-distance intrahemispheric pairs for three frequency ranges: 25–30 Hz, 30–35 Hz, and 40–48 Hz in post-stimulus 0–800 ms duration. The long-distance intrahemispheric pairs from both sides were fronto-parietal, fronto-temporal, fronto-temporoparietal, fronto-occipital, centro-occipital and parieto-occipital.ResultsThe sensory-evoked or event-related gamma coherences revealed that both treated and untreated AD patients had significantly increased values compared to healthy controls in all three sub-gamma bands. Moreover, the treated AD patients demonstrated significantly higher fronto-parietal gamma coherences during both sensory stimulation and oddball paradigm and lower occipito-parietal coherences during oddball paradigm in comparison to untreated AD patients.ConclusionThe present study demonstrated that an increase of gamma coherences was present in response to both visual sensory and cognitive stimulation in AD patients in all gamma sub-bands. Therefore, gamma oscillatory activity seems to be fundamental in brain functions at both the sensory and cognitive levels. The increase of gamma coherence values was not due to cholinergic treatment to any significant extent, as both treated and untreated AD patients had increased gamma coherence values compared to healthy controls. The use of coherence values reflecting brain connectivity holds potential for neuroimaging of AD and understanding brain dynamics related to the effects of medication.

A clinical trial to validate event-related potential markers of Alzheimer's disease in outpatient settings

IntroductionWe investigated whether event-related potentials (ERP) collected in outpatient settings and analyzed with standardized methods can provide a sensitive and reliable measure of the cognitive deficits associated with early Alzheimer's disease (AD). MethodsA total of 103 subjects with probable mild AD and 101 healthy controls were recruited at seven clinical study sites. Subjects were tested using an auditory oddball ERP paradigm. ResultsSubjects with mild AD showed lower amplitude and increased latency for ERP features associated with attention, working memory, and executive function. These subjects also had decreased accuracy and longer reaction time in the target detection task associated with the ERP test. DiscussionAnalysis of ERP data showed significant changes in subjects with mild AD that are consistent with the cognitive deficits found in this population. The use of an integrated hardware/software system for data acquisition and automated data analysis methods make administration of ERP tests practical in outpatient settings.

Non-rapid eye movement sleep instability in mild cognitive impairment: a pilot study

ObjectivePolysomnographic (PSG) studies in mild cognitive impairment (MCI) are not conclusive and are limited only to conventional sleep parameters. The aim of our study was to evaluate sleep architecture and cyclic alternating pattern (CAP) parameters in subjects with MCI, and to assess their eventual correlation with cognition. MethodsEleven subjects with MCI (mean age 68.5 ± 7.0 years), 11 patients with mild probable Alzheimer's disease (AD; mean age 72.7 ± 5.9 years), referred to the Outpatient Cognitive Disorders Clinic, and 11 cognitively intact healthy elderly individuals (mean age 69.2 ± 12.6 years) underwent ambulatory PSG for the evaluation of nocturnal sleep architecture and CAP parameters. ResultsRapid eye movement sleep, CAP rate, and CAP slow components (A1 index) were decreased in MCI subjects and to a greater extent in AD patients, compared to cognitively intact controls. AD showed also decreased slow wave sleep (SWS) relative to healthy elderly individuals. MCI nappers showed decreased nocturnal SWS and A1 subtypes compared to non-nappers. Several correlations between sleep variables and neuropsychological tests were found. ConclusionsMCI and AD subjects showed a decreased sleep instability correlated with their cognitive decline. Such a decrease may be considered as a potential biomarker of underlying neurodegeneration.

Inhibitory deterioration may contribute to hallucinations in Alzheimer's disease

Introduction. Although delusions and hallucinations are relatively common symptoms in individuals with Alzheimer's disease (AD), very little is known regarding underlying mechanisms. We examined whether these manifestations could be underpinned by psychological distress and executive impairments.Methods. Thirty-one participants with probable mild AD and 33 healthy older adults were administered a neuropsychological and clinical battery assessing delusions, hallucinations, anxiety, depression, episodic memory and executive functions (shifting, updating and inhibition).Results. Prevalence of delusions and hallucinations were significantly higher in AD participants compared to control participants. Further, hallucinations in AD participants were significantly correlated with poor inhibition, with the latter uniquely predicting the former, as compared to other variables. In addition, hallucinations in AD participants were associated with depression, a relationship that was further mediated by inhibition.Conclusion. Hallucinations in individuals with AD seem to be related to difficulties suppressing irrelevant thoughts, resulting in these irrelevant thoughts becoming confused with ongoing reality.

THE RESEARCH LUMBAR PUNCTURE: FURTHER EVIDENCE OF SAFETY AND TOLERABILITY WHEN UNDERTAKEN BY EXPERIENCED ANAESTHETISTS

The lumbar puncture was described in 1891 by Heinrich Quincke. Its use as a diagnostic aid in the ill patient with central nervous system pathology is well established. Its role as a research tool has a shorter history. With the advent of cerebrospinal fluid biomarkers, the research lumbar puncture is being undertaken more frequently to investigate a variety of conditions. Previous large series show a wide variation in the incidence of complications. In one, the authors report any adverse event as 11.7% and clinically significant adverse events as 3.97%. We have already shown that if undertaken by clinicians experienced in regional anaesthesia the rate of complications is considerably lower. We now describe additional data from our series as further evidence of this theory. In an audit of our practice, we analysed notes of 120 consecutive patients who underwent a lumbar puncture at the Glasgow Memory Clinic between October 2011 and May 2014. They were volunteers having cerebrospinal fluid biomarker analysis as part of commercial studies. All were mildly cognitively impaired or had probable mild Alzheimer's disease. The procedures were carried out two experienced consultant anaesthetists who regularly perform spinal anaesthesia as part of their routine clinical practice. Data was available for 118/120 patients (50 female, 68 male). Mean age 68.6 years. 102/118(86.4%) of procedures were completed at the first attempt, 14 (11.9%) on the second and 2 (1.7%) on the third. 3 patients (2.5%) complained of procedural back pain and 1 (0.8%) of back and leg pain. 2 (1.7%) had transient lower limb paraesthesiae. There were no bloody taps. The procedures were well tolerated with a very small percentage of transient symptoms. In the hands experienced anaesthetists using relatively narrow gauge spinal needles the Research Lumbar Puncture has a very low rate of immediate complications.

Development of a screening algorithm for Alzheimer's disease using categorical verbal fluency.

We developed a weighted composite score of the categorical verbal fluency test (CVFT) that can more easily and widely screen Alzheimer's disease (AD) than the mini-mental status examination (MMSE). We administered the CVFT using animal category and MMSE to 423 community-dwelling mild probable AD patients and their age- and gender-matched cognitively normal controls. To enhance the diagnostic accuracy for AD of the CVFT, we obtained a weighted composite score from subindex scores of the CVFT using a logistic regression model: logit (case) = 1.160+0.474× gender +0.003× age +0.226× education level – 0.089× first-half score – 0.516× switching score -0.303× clustering score +0.534× perseveration score. The area under the receiver operating curve (AUC) for AD of this composite score AD was 0.903 (95% CI = 0.883 – 0.923), and was larger than that of the age-, gender- and education-adjusted total score of the CVFT (p<0.001). In 100 bootstrapped re-samples, the composite score consistently showed better diagnostic accuracy, sensitivity and specificity for AD than the total score. Although AUC for AD of the CVFT composite score was slightly smaller than that of the MMSE (0.930, p = 0.006), the CVFT composite score may be a good alternative to the MMSE for screening AD since it is much briefer, cheaper, and more easily applicable over phone or internet than the MMSE.

Early Diagnosis of Alzheimer's Disease and Parkinson's Disease Associated with Dementia Using Cerebral Perfusion SPECT

Background: Since patterns of cognitive dysfunction in mild Parkinson's disease associated with dementia (PDD) are similar to those in mild Alzheimer's disease (AD), it is difficult to accurately differentiate between these two types of dementia in their early phases using neuropsychological tests. The purpose of the current study was to investigate differences in cerebral perfusion patterns of patients with AD and PDD at the earliest stages using single photon emission computed tomography (SPECT). Methods: We consecutively recruited 31 patients with mild PDD, 32 patients with mild probable AD and 33 age-matched healthy subjects. All subjects underwent ^99mTc-hexamethylpropyleneamine oxime perfusion SPECT and completed general neuropsychological tests. Results: We found that both mild PDD and AD patients showed distinct hypoperfusion in frontal, parietal and temporal regions, compared with healthy subjects. More importantly, hypoperfusion in occipital and cerebellar regions was observed only in mild PDD. Conclusion: The observation of a significant decrease in cerebral perfusion in occipital and cerebellar regions in patients with mild PDD is likely useful to differentiate between PDD and AD at the earliest stages.

Ecological Evaluation of Executive Functions in Mild Cognitive Impairment and Alzheimer Disease

Executive deficits characterize the initial phases of Alzheimer disease (AD) and mild cognitive impairment (MCI), and are clinically correlated to neuropsychiatric symptoms and functional loss. The aim of this study was to determine the accuracy of the Behavioral Assessment of the Dysexecutive Syndrome test (BADS) for comparing the performance between patients with amnestic MCI (aMCI) and mild AD and for detecting early signs of alterations in executive functions. BADS was performed on 60 healthy controls, 20 patients with aMCI, and 40 mild probable AD patients (20 early-onset AD patients and 20 late-onset AD patients). Significant differences in battery performance were found among groups on the BADS subtests Rule Shift Cards, Program of Action, Zoo Map, 6 Modified Elements, and 3 total scores. Early changes in executive functions were detected in both AD (irrespective of age of onset) and aMCI patients. The BADS proved useful for differentiating between these patient groups. Our results confirmed the presence of early alterations in executive functions among aMCI and mild AD patients.

Destination memory in mild Alzheimer's Disease.

In order to assess their destination memory, sixteen patients with probable mild Alzheimer Disease (AD), sixteen older adults and 16 young adults were asked to tell facts to pictures. On a subsequent task, they were asked to remember whether they had previously told that fact to that face or not. AD patients showed poorer destination recall than the older adults, and the older adults showed poorer destination recall than the young adults. Our results suggest that destination memory is highly impaired in AD.

Differences of Regional Cerebral Blood Flow between Early Alzheimer’s Disease and Parkinson’s Disease Associated with Dementia on99mTc-Hexamethyl Propylene Amine Oxime Perfusion Single Photon Emission Computed Tomography

Background: Alzheimer's disease (AD) and Parkinson's disease associated with dementia (PDD) are considered to be fre- quent types of cortical and subcortical dementia. Definitive diagnosis of neurodegenerative diseases is impossible without biopsy. Single photon emission computed tomography (SPECT) of the brain has long been used for years with cognitive disorders. Nevertheless, differential brain perfusion of patients with PDD and AD who exhibit mild dementia has not been reported. Therefore, we investigated the differences in the cerebral perfusional pattern using perfusion SPECT between mild AD and mild PDD to help clarify the diagnosis in the early stage of these dementias, since accurate diagnosis is crucial in deci- sion regarding treatment, appropriate advice, management and prognosis. Methods: Thirty-one patients with mild PDD and 32 patients with mild probable AD were enrolled in this study. All subjects underwent 99m Tc-hexamethyl propylene amine oxime perfusion SPECT and general neuropsychological tests, and these da- ta including perfusion images were analyzed. Results: Perfusion SPECT showed hypoperfusion in frontal, parietal and temporal regions in both PDD and AD patients with mild dementia. Hypoperfusion in the occipital and cerebellar regions was significantly apparent in only PDD patients. Conclusion: Comparison of mild PDD with mild AD showed a significantly decreased perfusion in the occipital and cer- ebellar region in patients with mild PDD. Cerebral perfusion in the occipital region and the cerebellum could be a crucial diffe- rential diagnostic method of these diseases in the early phase. Further studies are needed for a definitive conclusion.

Slowing of Information Processing in Alzheimer Disease

To use Sternberg's Additive Factor Method to determine whether patients with mild Alzheimer disease (AD) are slow in information processing and/or response execution. We gave an odd-even categorization task to 16 patients with probable mild AD and 17 age-matched healthy controls. We recorded reaction and movement times to stimuli varying for noise, target set size, stimulus-response compatibility, and fore-period interval, to probe the cognitive and motor stages of information processing. Both groups performed the task accurately, indicating good preservation of odd-even categorization in mild AD. The AD group's reaction times were similar to the controls' across conditions, and not selectively affected in any of the cognitive stages of the Additive Factor Method. However, the AD group's movement times were slower than the controls' across conditions. AD patients' performance on a task requiring categorization ability was slowed more by motor than cognitive components of information processing. When evaluating the performance of patients with AD in reaction-time paradigms, we should not attribute group differences solely to differences in cognitive processing. Execution components should also be considered.