Construction of a (18)F-FDG PET normative database of Japanese healthy elderly subjects and its application to demented and mild cognitive impairment patients

Selection of the optimal intensity normalization region for FDG-PET studies of normal aging and Alzheimer's disease

The primary method for measuring brain metabolism in humans is positron emission tomography (PET) imaging using the tracer 18F-fluorodeoxyglucose (FDG). Standardized uptake value ratios (SUVR) are commonly calculated from FDG-PET images to examine intra- and inter-subject effects. Various reference regions are used in the literature of FDG-PET studies of normal aging, making comparison between studies difficult. Our primary objective was to determine the optimal SUVR reference region in the context of healthy aging, using partial volume effect (PVE) and non-PVE corrected data. We calculated quantitative cerebral metabolic rates of glucose (CMRg) from PVE-corrected and non-corrected images from young and older adults. We also investigated regional atrophy using magnetic resonance (MR) images. FreeSurfer 6.0 atlases were used to explore possible reference regions of interest (ROI). Multiple regression was used to predict CMRg data, in each FreeSurfer ROI, with age and sex as predictors. Age had the least effect in predicting CMRg for PVE corrected data in the pons (r2 = 2.83 × 10-3, p = 0.67). For non-PVE corrected data age also had the least effect in predicting CMRg in the pons (r2 = 3.12 × 10-3, p = 0.67). We compared the effects of using the whole brain or the pons as a reference region in PVE corrected data in two regions susceptible to hypometabolism in Alzheimer's disease, the posterior cingulate and precuneus. Using the whole brain as a reference region resulted in non-significant group differences in the posterior cingulate while there were significant differences between all three groups in the precuneus (all p < 0.004). When using the pons as a reference region there was significant differences between all groups for both the posterior cingulate and the precuneus (all p < 0.001). Therefore, the use of the pons as a reference region is more sensitive to hypometabism changes associated with Alzheimer's disease than the whole brain.

The Cingulate Island Sign on FDG-PET vs. IMP-SPECT to Assess Mild Cognitive Impairment in Alzheimer's Disease vs. Dementia with Lewy Bodies

BACKGROUND AND PURPOSE

The cingulate island sign (CIS) on ¹⁸ F-fluorodeoxyglucose positron emission tomography (FDG-PET); ie, the relative preservation of mid-posterior cingulate cortex metabolism, is a supportive biomarker in the diagnostic criteria for dementia with Lewy bodies (DLB). However, limited information is currently available on the diagnostic value of the CIS on FDG-PET or ¹²³ I-iodoamphetamine single-photon emission computed tomography (IMP-SPECT) for differentiating between mild cognitive impairment (MCI) due to Alzheimer's disease (AD) (MCI-AD) and MCI due to DLB (MCI-DLB).

METHODS

We examined the CIS ratio in 9 AD patients, 9 DLB patients, 8 patients with MCI-AD, and 9 patients with MCI-DLB using FDG-PET and IMP-SPECT. The CIS ratio was calculated using NEUROSTAT software.

RESULTS

In the dementia groups, a receiver operating characteristic analysis of the CIS ratio showed significant accuracy for differentiating between AD and DLB on FDG-PET and IMP-SPECT. In the MCI groups, only the FDG-PET derived CIS ratio displayed significant accuracy for differentiating between AD and DLB.

CONCLUSIONS

The FDG-PET and IMP-SPECT derived CIS ratios are both useful for differentiating between AD and DLB. The FDG-PET derived CIS ratio is more valuable than the IMP-SPECT derived CIS ratio for differential diagnosis in patients with MCI. A larger study is needed to confirm these results.

Longitudinal effects of aging on 18F-FDG distribution in cognitively normal elderly individuals

Previous studies of aging effects on fluorine-18-labeled fluorodeoxyglucose (¹⁸F-FDG) distribution have employed cross-sectional designs. We examined aging effects on ¹⁸F-FDG distribution using both cross-sectional and longitudinal assessments. We obtained two ¹⁸F-FDG positron emission tomography scans at two different time points from 107 cognitively normal elderly participants. The participants’ mean ages at baseline and second scans were 67.9 and 75.7, respectively. The follow-up period ranged from 4 to 11 years with a mean of 7.8 years. The voxel-wise analysis revealed significant clusters in which ¹⁸F-FDG uptake was decreased between baseline and second scans (p < 0.05, family-wise error corrected) in the anterior cingulate cortex (ACC), posterior cingulate cortex/precuneus (PCC/PC), and lateral parietal cortex (LPC). The cross-sectional analysis of ¹⁸F-FDG uptake and age showed significant correlations in the ACC (p = 0.016) but not the PCC/PC (p = 0.240) at baseline, and in the ACC (p = 0.004) and PCC/PC (p = 0.002) at the second scan. The results of longitudinal assessments suggested that ¹⁸F-FDG uptake in the ACC, PCC/PC, and LPC decreased with advancing age in cognitively normal elderly individuals, and those of the cross-sectional assessments suggested that the trajectories of age-associated ¹⁸F-FDG decreases differed between the ACC and PCC/PC.

The Use of Short Versions of the Japanese WAIS-III to Aid in Differentiation Between Alzheimer's Disease and Dementia with Lewy Bodies

Objective

We examined the cognitive characteristics of patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) using the Wechsler Adult Intelligent Scale-Third Edition (WAIS-III). In addition, the utility of short versions of WAIS-III for estimating IQ scores and index scores were examined.

Methods

The subjects were 83 patients with probable AD, 33 patients with probable DLB, and 83 cognitively normal individuals.

Results

Patients with DLB showed significantly lower scores in Performance IQ and Processing Speed compared with those with AD. The short versions of WAIS-III with Information, Similarities, Arithmetic, Digit Span, Picture Completion, Digit Symbol-Coding, and Block Design demonstrated relatively small amount of error, high correlations, and reliabilities with the full version.

Conclusions

The results indicated that Performance IQ and Processing Speed in WAIS-III can be an indicator for differentiating AD and DLB in WAIS-III, and a short version obtained by the Similarities, Information, Picture Completion, Block Design, Arithmetic, Digit Span, and Digit-Symbol Coding yields high accuracy and can be used to estimate full-scale IQ scores on the WAIS-III.

Study of the Influence of Age in 18F-FDG PET Images Using a Data-Driven Approach and Its Evaluation in Alzheimer's Disease

Objectives

¹⁸F-FDG PET scan is one of the most frequently used neural imaging scans. However, the influence of age has proven to be the greatest interfering factor for many clinical dementia diagnoses when analyzing ¹⁸F-FDG PET images, since radiologists encounter difficulties when deciding whether the abnormalities in specific regions correlate with normal aging, disease, or both. In the present paper, the authors aimed to define specific brain regions and determine an age-correction mathematical model.

Methods

A data-driven approach was used based on 255 healthy subjects.

Results

The inferior frontal gyrus, the left medial part and the left medial orbital part of superior frontal gyrus, the right insula, the left anterior cingulate, the left median cingulate, and paracingulate gyri, and bilateral superior temporal gyri were found to have a strong negative correlation with age. For evaluation, an age-correction model was applied to 262 healthy subjects and 50 AD subjects selected from the ADNI database, and partial correlations between SUVR mean and three clinical results were carried out before and after age correction.

Conclusion

All correlation coefficients were significantly improved after the age correction. The proposed model was effective in the age correction of both healthy and AD subjects.

Differential Effects of the Factor Structure of the Wechsler Memory Scale-Revised on the Cortical Thickness and Complexity of Patients Aged Over 75 Years in a Memory Clinic Setting

The Wechsler Memory Scale-Revised (WMS-R) is one of the internationally well-known batteries for memory assessment in a general memory clinic setting. Several factor structures of the WMS-R for patients aged under 74 have been proposed. However, little is known about the factor structure of the WMS-R for patients aged over 75 years and its neurological significance. Thus, we conducted exploratory factor analysis to determine the factor structure of the WMS-R for patients aged over 75 years in a memory clinic setting. Regional cerebral blood flow (rCBF) was calculated from single-photon emission computed tomography data. Cortical thickness and cortical fractal dimension, as the marker of cortical complexity, were calculated from high resolution magnetic resonance imaging data. We found that the four factors appeared to be the most appropriate solution to the model, including recognition memory, paired associate memory, visual-and-working memory, and attention as factors. Patients with mild cognitive impairments showed significantly higher factor scores for paired associate memory, visual-and-working memory, and attention than patients with Alzheimer's disease. Regarding the neuroimaging data, the factor scores for paired associate memory positively correlated with rCBF in the left pericallosal and hippocampal regions. Moreover, the factor score for paired associate memory showed most robust correlations with the cortical thickness in the limbic system, whereas the factor score for attention correlated with the cortical thickness in the bilateral precuneus. Furthermore, each factor score correlated with the cortical fractal dimension in the bilateral frontotemporal regions. Interestingly, the factor scores for the visual-and-working memory and attention selectively correlated with the cortical fractal dimension in the right posterior cingulate cortex and right precuneus cortex, respectively. These findings demonstrate that recognition memory, paired associate memory, visual-and-working memory, and attention can be crucial factors for interpreting the WMS-R results of elderly patients aged over 75 years in a memory clinic setting. Considering these findings, the results of WMS-R in elderly patients aged over 75 years in a memory clinic setting should be cautiously interpreted.

Regional cerebral glucose metabolism in systemic lupus erythematosus patients with major depressive disorder

OBJECTIVES

Depression is frequently observed in patients with systemic lupus erythematosus (SLE). Neuropsychiatric SLE (NPSLE) patients often exhibit cerebral hypometabolism, but the association between cerebral metabolism and depression remains unclear. To elucidate the features of cerebral metabolism in SLE patients with depression, we performed brain 18F-fluoro-d-glucose positron emission tomography (FDG-PET) on SLE patients with and without major depressive disorder.

METHODS

We performed brain FDG-PET on 20 SLE subjects (5 male, 15 female). The subjects were divided into two groups: subjects with major depressive disorder (DSLE) and subjects without major depressive disorder (non-DSLE). Cerebral glucose metabolism was analyzed using the three-dimensional stereotactic surface projection (3D-SSP) program. Regional metabolism was evaluated by stereotactic extraction estimation (SEE), in which the whole brain was divided into segments.

RESULTS

Every SLE subject exhibited cerebral hypometabolism, in contrast to the normal healthy subjects. Regional analysis revealed a significantly lower ER in the left medial frontal gyrus (p=0.0055) and the right medial frontal gyrus (p=0.0022) in the DSLE group than in the non-DSLE group.

CONCLUSION

Hypometabolism in the medial frontal gyrus may be related to major depressive disorder in SLE. Larger studies are needed to clarify this relationship.

Regional glucose hypometabolic spread within the primary motor cortex is associated with amyotrophic lateral sclerosis disease progression: A fluoro-deoxyglucose positron emission tomography study

Objective

Here we investigate the process of neurodegeneration in amyotrophic lateral sclerosis (ALS). The relationship between the cortical field spreading of glucose metabolic decreases in the primary motor cortex (PMC) and the progression of corresponding extremity dysfunction was evaluated using [¹⁸F] fluoro-deoxyglucose (FDG)-positron emission tomography (PET).

Methods

Patients with ALS underwent [¹⁸F] FDG-PET and the resulting datasets were individually contrasted against healthy controls using the NEUROSTAT software. The extent ratio was defined as the proportion of pixels with a significant Z-score decrease within regions of the primary motor cortex (precentral gyrus or paracentral lobule) opposite to the impaired upper extremities (UEs) or lower extremities (LEs), respectively. Clinical symptoms in all extremities were assessed using an upper motor neuron (UMN) score and the MRC (Medical Research Council) sum score upon physical examination. Cross-sectional correlations were analysed between clinical symptoms, the duration of these symptoms, and the extent ratio.

Results

Nineteen regions of the primary motor cortex corresponding to symptomatic limb in 10 participants were evaluated. In the corresponding region of the primary motor cortex, the extent ratio increased (same meaning as hypometabolic area spread) in association with symptom duration (r_s = 0.5, p = 0.03). Neither UMN nor lower motor neuron (LMN) scores were correlated with symptom duration. Three out of 19 impaired regions did not show upper motor neuron (UMN) signs upon physical examination. The extent ratio and UMN score-controlled symptom duration were partially correlated (r_s = 0.5, p = 0.05).

Conclusions

In patients with ALS, glucose metabolism decreased in the impaired side of the primary motor cortex depending on the clinical symptom progression in the corresponding extremities, regardless of the presence of clinical UMN signs. A decrement in glucose metabolism on FDG-PET corresponding to symptoms in the primary motor cortex might be an indicator of the time-dependent course of ALS neurodegeneration.

Characteristics of mild cognitive impairment tending to convert into Alzheimer's disease or dementia with Lewy bodies: A follow-up study in a memory clinic

AIM

To determine characteristics of MCI that can predict whether patients will go on to develop AD or DLB.

METHODS

Ninety-three patients diagnosed with MCI underwent neuropsychological and neuroimaging examinations, and were followed-up for a mean of 44.9±19.3months. They were divided into four MCI subtypes (amnestic/non-amnestic MCI, single/multiple domain) according to neuropsychological findings, and into three other MCI categories (AD-type PET, DLB-type PET, and unknown-type PET) based on (18)F-fluorodeoxyglucose PET findings. Patients who were eventually diagnosed with AD, DLB, other dementia, or remained MCI were analyzed in relation to the groups to which they had initially been allocated at the MCI stage.

RESULTS

Clinical diagnosis after follow-up determined AD in 21 patients (22.6%), DLB in 12 patients (12.9%), other dementia in 2 patients (2.2%), and non-converter in 58 patients (62.3%). Amnestic single-domain MCI and AD-type PET tended to convert into AD. Amnestic multiple-domain MCI and DLB-type PET tended to convert into DLB. A few patients with AD-type PET later developed DLB, and some with DLB-type PET later developed AD.

CONCLUSIONS

Predicting which type of dementia a person with MCI will later develop might be possible based on early assessment with clinical symptoms in conjunction with neuropsychological and (18)F-fluorodeoxyglucose PET findings.

123I-FP-CIT SPECT findings and its clinical relevance in prodromal dementia with Lewy bodies

PURPOSE

Evidence for the prodromal stage of dementia with Lewy bodies (DLB) is very limited. To address this issue, we investigate the ¹²³I-FP-CIT SPECT measure of dopamine transporter binding finding and its clinical relevance.

METHODS

We enrolled subjects into a prodromal DLB group (PRD-DLB) (n = 20) and clinical DLB group (CLIN-DLB) (n = 18) and compared these groups with an Alzheimer's disease control group (AD) (n = 10). PRD-DLB was defined as patients having the non-motor symptoms associated with Lewy body disease (LBD) [i.e. REM sleep behavior disorder (RBD), olfactory dysfunction, autonomic dysfunction, and depression] and showing characteristic diffuse occipital hypometabolism in ¹⁸F-FDG PET. CLIN-DLB was defined as patients fulfilling the established criteria of probable DLB. Striatal specific binding ratio (SBR) of ¹²³I-FP-CIT SPECT was used for objective group comparisons. The correlations between SBR and cognitive function (MMSE), motor symptoms (UPDRS3), and duration of LBD-associated non-motor symptoms were compared between the two DLB groups.

RESULTS

Mean SBR scores of both PRD-DLB and CLIN-DLB were significantly lower than those of AD. No correlation was found between SBR and MMSE scores. Both in the CLIN-DLB and total DLB groups, SBR scores were negatively correlated with UPDRS3 scores, whereas no correlation was found in PRD-DLB. Among the LBD-related non-motor symptoms, duration of olfactory dysfunction, and RBD demonstrated negative correlation with SBR scores in PRD-DLB.

CONCLUSION

¹²³I-FP-CIT SPECT may play a role for detecting DLB among the subjects in prodromal stage. During this stage, long-term olfactory dysfunction and/or RBD may indicate more severe degeneration of the nigro-striatal dopaminergic pathway.

Early differential diagnosis between Alzheimer's disease and dementia with Lewy bodies: Comparison between (18)F-FDG PET and (123)I-IMP SPECT

Both (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and (123)I-iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) have been used for the differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Less information is available, however, regarding the differential diagnosis of mild cognitive impairment (MCI) due to AD and MCI due to DLB. We examined nine AD patients (AD group), nine DLB patients (DLB group), eight MCI due to AD patients (MCI-AD group), and nine MCI due to DLB patients (MCI-DLB group) with FDG PET and IMP SPECT using a well-characterized normal database and a stereotactic extraction estimation method. In the AD and DLB groups, receiver operating characteristic (ROC) analysis in the occipital regions showed significant accuracy of both FDG PET and IMP SPECT for the differential diagnosis. In the MCI-AD and MCI-DLB groups, ROC analysis showed significant accuracy of only FDG PET for the differential diagnosis. Both FDG PET and IMP SPECT would be useful for the differential diagnosis between AD and DLB. For the differential diagnosis of MCI-AD versus MCI-DLB, FDG PET would be more useful than IMP SPECT.

Brain metabolism in substance-induced psychosis and schizophrenia: a preliminary PET study

INTRODUCTION

The relation between schizophrenia and cannabis abuse has been widely discussed from etiopathogenetic, psychopathological and neurometabolic points of view. Relatively little has been written about the differences between schizophrenia with co-occurrent cannabis abuse and substance-induced psychotic disorder (SIPD). Given these premises, our study aims to investigate the psychopathological and neurometabolic features of these clinical entities.

METHODS

We enrolled patients experiencing an acute psychotic episode, affected either by schizophrenia with or without cannabis abuse (SCZ +/- CA; n = 5 and n = 5, respectively) with recent onset (<5 years of illness) or by SIPD (n = 6), as diagnosed by the Structured Clinical Interview for DSM-IV Axis I. Patients affected by SIPD were all cannabis abusers. All patients were assessed with the PANSS (Positive and Negative Scale for Schizophrenia), urinary toxicological tests and brain 18-FDG-PET scanning in resting condition. Statistical analysis (ANOVA) was performed with Statistical Parametric Mapping SPM8 and Scenium software.

RESULTS

Bilateral hypermetabolism in the posterior cingulum and the precuneus (p < 0.001) was observed in SIPD patients compared to patients with schizophrenia, with or without cannabis abuse.

CONCLUSIONS

Our preliminary PET findings suggest that substance abuse may cause increased brain metabolism in patients with induced psychosis but not in those with schizophrenia. These differences in brain metabolism were found in the posterior cingulum and precuneus, which are two core regions of the default mode network in humans.

Prediction of later clinical course by a specific glucose metabolic pattern in non-demented patients with probable REM sleep behavior disorder admitted to a memory clinic: A case study

The present study is a follow-up study of 11 non-demented patients with probable rapid eye movement (REM) sleep behavior disorder (RBD) at our memory clinic. During the follow-up period (mean±SD of 46.7±6.4 months), all 11 patients exhibited cognitive decline: four (Group A) exhibited core clinical features of dementia with Lewy bodies (DLB), along with severe cognitive decline, and were subsequently diagnosed as having probable DLB; four (Group B) did not exhibit core clinical features of DLB; and the remaining three (Group C) were diagnosed as having Parkinson's disease with dementia (PDD). Positron emission tomography with fluorodeoxyglucose-F18 at baseline revealed that Groups A and B exhibited glucose hypometabolism in the occipital lobe, especially in the primary visual cortex, and Group A tended to present hypometabolism in the parieto-temporal area as well. Group C tended to present hypometabolism in the medial prefrontal area and anterior cingulate gyrus. Neuropsychological examinations indicated poor performance in verbal memory and visuoperception in all groups. This case study suggests that patterns of hypometabolism and neuropsychological examinations at baseline may be indicators of the later clinical course of probable RBD patients.

Cognitive dysfunction in patients with very mild Alzheimer's disease and amnestic mild cognitive impairment showing hemispheric asymmetries of hypometabolism on ¹⁸F-FDG PET

OBJECTIVE

We investigated cognitive dysfunction in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) who present hemispheric asymmetries of cerebral metabolic rate of glucose (CMRglc) decrease on (18) F-fluorodeoxyglucose positron emission tomography.

METHODS

Based on the hemispheric asymmetries of CMRglc decrease in the posterior cingulate cortex, precuneus, and parietotemporal cortex, the patients were divided into three groups (a left-dominant hypometabolism group, a right-dominant hypometabolism group, and a non-dominant hypometabolism group). CMRglc decrease in the whole brain was controlled among the three groups. All the patients underwent mini-mental state examination (MMSE), Wechsler Memory Scale-Revised (WMS-R), and Wechsler Adult Intelligent Scale-Third (WAIS-III).

RESULTS

There were no significant differences in MMSE and WAIS-III scores among the three groups. In WMS-R, the results indicated that the left-dominant group demonstrated significantly lower scores in verbal memory than the other two groups. Furthermore, the left-dominant group had a greater tendency to be diagnosed with AD rather than aMCI.

CONCLUSIONS

Patients with AD and aMCI showing left-dominant hypometabolism tend to show severer impairment in verbal memory function and to be diagnosed with AD dementia.

Clinical profiles of dementia with Lewy bodies with and without Alzheimer's disease-like hypometabolism

OBJECTIVES

It is well known that Alzheimer's disease (AD)-type pathology is commonly present in dementia with Lewy bodies (DLB) brains and that the degree of AD-type pathology has an influence on the clinical characteristics of DLB. Although significant hypometabolism in the temporoparietal/precuneus on [(18)F]fluoro-d-glucose ((18)F-FDG) positron emission tomography (PET) scans is considered to support a diagnosis of AD, some DLB patients also exhibit this metabolic pattern. The clinical significance of the metabolic pattern on DLB remains unknown.

METHODS

Twenty-three DLB patients, 10 AD patients, and 11 controls underwent (18)F-FDG PET scans. According to the degree of hypometabolism in the parietal/precuneus regions, representing the AD-like metabolic pattern, 12 patients were placed in the DLB-AD(+) group and 11 patients were placed in the DLB-AD(-) group. The demographics and clinical variables were compared among the four groups.

RESULTS

In addition to the parietal/precuneus regions, the DLB-AD(+) group exhibited significantly greater posterior cingulate hypometabolism than the DLB-AD(-) group, although occipital metabolism did not differ. The prevalence of visual hallucinations and extracampine hallucinations, and the Bender-Gestalt test score were significantly higher in the DLB-AD(+) group than the DLB-AD(-) group, although there were no differences in the demographics and other examined clinical variables between the two DLB groups. These clinical differences were absent in the DLB-AD(-) group, AD group, and controls.

CONCLUSIONS

Parietal/precuneus hypometabolism may be associated with clinical characteristics in DLB patients. Further multiple imaging modalities that are sensitive to AD-type pathology are needed to reveal the neurobiological basis of the AD-like metabolic pattern.

Three presenile patients in which neuropsychological and neuroimaging examinations suggest possible progression to dementia with Lewy bodies

We report three presenile patients who were initially suspected of having Alzheimer's disease (AD) or being in the prodromal stage of AD, regardless of visuoperceptual dysfunctions in daily living, because they lacked the core features and prodromal non-motor symptoms of dementia with Lewy bodies. Subsequently, progression to dementia with Lewy bodies was suspected based on neuropsychological and neuroimaging findings; additionally, one of the three patients suffered from visual hallucinations. Neuropsychological examinations such as subjective contours, cube copying and block design in the Wechsler Adult Intelligence Scale-III revealed visuoperceptual dysfunction in all three patients even when other cognitive functions were rather preserved. Brain magnetic resonance imaging revealed no significant brain atrophy, including in the parieto-occipital area and the hippocampus, while brain (18)F-fluorodeoxyglucose positron emission tomography demonstrated right dominant metabolic reductions in the occipital lobe, including the primary visual cortex, in all three patients. We suggest the possibility of progression to dementia with Lewy bodies, but not AD or posterior cortical atrophy. Regardless of the presence of core features and prodromal non-motor symptoms, this progression is suggested when there are difficulties only in higher-level visual processing such as subjective contours and block design in the Wechsler Adult Intelligence Scale-III, no significant atrophy of the parieto-occipital area and hippocampus on brain magnetic resonance imaging, and hypometabolism in the occipital lobe including the primary visual cortex on brain (18)F-fluorodeoxyglucose positron emission tomography.

Primary visual cortical metabolism and rapid eye movement sleep behavior disorder in dementia with Lewy bodies

AIM

Significant glucose hypometabolism in the primary visual cortex (PVC) is considered to support a diagnosis of dementia with Lewy bodies (DLB), but its relationship to the clinical features remains unknown. The purpose of this study was to assess the association between the metabolic pattern and clinical variables in DLB.

METHODS

A total of 27 DLB patients who underwent [18F]fluoro-d-glucose (18F-FDG) positron emission tomography scans were examined. Demographics and clinical variables were compared between patients with and without glucose hypometabolism in the PVC. The correlations between the cerebral metabolic rate of glucose in the PVC and clinical variables were also investigated.

RESULTS

Only the onset age of probable rapid eye movement sleep behavior disorder (RBD) was significantly different between patients with and withoutglucose hypometabolism in the PVC, being younger in patients with the metabolic pattern; there were no other differences in clinical variables. The onset age of probable RBD was significantly correlated with the cerebral metabolic rate of glucose in the PVC.

CONCLUSIONS

Glucose hypometabolism in the PVC provides a potential mechanism for the link between antecedent RBD and the subsequent development of dementia in DLB patients. Glucose hypometabolism in the PVC may represent the effect of the pathophysiological process of DLB on RBD rather than a distinct condition in the disease progression. The physiological aspects of the link between this metabolic pattern and the onset of RBD remain unclear.

Characterizing the normative profile of 18F-FDG PET brain imaging: sex difference, aging effect, and cognitive reserve

The aim of this study was to investigate findings of positron emission tomography with 18F-fluorodeoxyglucose (18F-FDG PET) in normal subjects to clarify the effects of sex differences, aging, and cognitive reserve on cerebral glucose metabolism. Participants comprised 123 normal adults who underwent 18F-FDG PET and a neuropsychological battery. We used statistical parametric mapping (SPM8) to investigate sex differences, and aging effects. The effects of cognitive reserve on 18F-FDG uptake were investigated using years of education as a proxy. Finally, we studied the effect of cognitive reserve on the recruitment of glucose metabolism in a memory task by dichotomizing the data according to educational level. Our results showed that the overall cerebral glucose metabolism in females was higher than that in males, whereas male participants had higher glucose metabolism in the bilateral inferior temporal gyri and cerebellum than females. Age-related hypometabolism was found in anterior regions, including the anterior cingulate gyrus. These areas are part of the attentional system, which may decline with aging even in healthy elderly individuals. Highly educated subjects revealed focal hypermetabolism in the right hemisphere and lower recruitment of glucose metabolism in memory tasks. This phenomenon is likely a candidate for a neural substrate of cognitive reserve.

Neuropsychological detection of the early stage of amnestic mild cognitive impairment without objective memory impairment

AIM

We investigate the assessment method to detect the early stage of amnestic mild cognitive impairment (aMCI) using Wechsler Memory Scale - Revised (WMS-R) and Wechsler Adult Intelligence Scale - Third Edition (WAIS-III).

METHODS

Three groups (normal group, aMCI group, and early aMCI group), controlled for age and years of education, underwent brain (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET), WAIS-III, WMS-R, and other tests. The early aMCI group does not fulfill the clinical diagnostic criteria of aMCI because patients do not have objective memory impairment, but their clinical symptoms and results of (18)F-FDG PET indicate that they should be included in the category of aMCI.

RESULTS

The discrepancy of scores between Verbal IQ and General Memory had the highest accuracy in discriminating between normal and early aMCI groups.

CONCLUSION

The cutoff point determined in this study is useful to detect an early stage of aMCI, which may be distinguished from aMCI using the current criteria.

Dementia with Lewy bodies: early diagnostic challenges

Dementia with Lewy bodies (DLB) is defined pathologically as neurodegeneration associated with Lewy bodies (LB). LB-related symptoms, including olfactory dysfunction, dysautonomia, and mood and sleep disorders, are increasingly recognized as clinical signs that enable the early detection of DLB, because these symptoms often antedate dementia by years or even decades. It remains unknown if the clinical history of LB-related symptoms is sufficient for the prodromal state of DLB to be suspected in memory clinics. We retrospectively investigated the clinical courses, including olfactory dysfunction, dysautonomia, depression, and rapid eye movement sleep behaviour disorder, of 90 patients with probable DLB. The timing of LB-related symptoms that preceded or followed relative to the onset of memory loss was calculated. LB-related symptoms were present in 79 of 90 patients (87.8%) with probable DLB before or at the time of memory loss onset. These symptoms preceded the onset of memory loss between 1.2 and 9.3 years. We also report on four non-demented patients with a clinical history of LB-related symptoms in our memory clinic. All four patients showed reduced cardiac [(123) I]-metaiodobenzylguanidine levels. Moreover, [(18) F]fluoro-D-glucose positron emission tomography scans revealed glucose hypometabolism in the occipital cortex in two patients. One patient converted to probable DLB with the development of parkinsonism 2 years after major depression was diagnosed. Based on a clinical history of LB-related symptoms, we propose a conceptual framework to identify these symptomatic but non-demented individuals that led us to suspect the underlying pathophysiology of Lewy body disease. Further prospective study is warranted to determine the clinical significance of LB-related symptoms in non-demented patients.

Intelligence or years of education: which is better correlated with memory function in normal elderly Japanese subjects?

BACKGROUND

We compared differences in intelligence and memory function between normal elderly Japanese subjects with more years of education and those with fewer years of education. We also investigated clinical and neuropsychological factors that are strongly correlated with memory function.

METHODS

There were 118 normal elderly subjects who underwent the Mini-Mental State Examination, Wechsler Adult Intelligence Scale, 3rd edition (WAIS-III), and Wechsler Memory Scale Revised. Subjects with at least 13 years of education were categorized as the H group, and those with 12 years of education or less were categorized as the L group.

RESULTS

Age and Mini-Mental State Examination scores were not significantly different between the two groups. On the WAIS-III, there were significant differences between the two groups in Verbal IQ and Full Scale IQ. On the Wechsler Memory Scale Revised, there were significant differences between the two groups in Visual Memory, General Memory, and Delayed Recall. Correlation coefficients between memory function and the other factors demonstrated significant but weak correlations between years of education and General Memory (R = 0.22) and between years of education and Delayed Recall (R = 0.20). Strong correlations were found between Verbal IQ and Verbal Memory (R = 0.45), between Verbal IQ and General Memory (R = 0.49), between Full Scale IQ and General Memory (R = 0.50) and between Full Scale IQ and Delayed Recall (R = 0.48).

CONCLUSIONS

In normal elderly Japanese subjects, years of education weakly correlated with memory function while Verbal IQ, Full Scale IQ and Verbal Comprehension on WAIS-III had stronger correlations with memory function. Verbal IQ and Verbal Comprehension on WAIS-III were found to be insusceptible to the cognitive decline characteristic of Alzheimer's disease or amnestic mild cognitive impairment. Therefore, verbal intelligence, as measured by Verbal IQ and Verbal Comprehension, may be the most useful factor for inferring premorbid memory function in Alzheimer's disease or amnestic mild cognitive impairment patients.

Glucose hypometabolism in primary visual cortex is commonly associated with clinical features of dementia with Lewy bodies regardless of cognitive conditions

BACKGROUND

Although metabolic reduction in the primary visual cortex on [(18) F]-fluoro-d-glucose (FDG) positron emission tomographic (PET) scans is the hallmark of dementia with Lewy bodies (DLB) for differential diagnosis from Alzheimer's disease, the clinical significance of the metabolic pattern in patients without dementia remains unknown. The purpose of this study was to investigate the clinical profiles of patients without dementia with the metabolic pattern and its relevance to DLB.

METHODS

Of 145 individuals who underwent (18) F-FDG PET, 25 patients with glucose hypometabolism in the primary visual cortex were identified based on three-dimensional stereotactic surface projection images through comparison with a normative database. The frequency of core and suggestive clinical features of DLB was compared between the groups with and without the metabolic pattern.

RESULTS

Of 25 patients with glucose hypometabolism in the primary visual cortex, 12 exhibited more than two core features of DLB (probable DLB group) and 6 had rapid eye movement sleep behavior disorder (possible DLB group). Three patients exhibited memory loss without any core or suggestive features but with reduced cardiac iodine-123 metaiodobenzylguanidine uptake. Ten of these 21 patients exhibited no dementia. The proportion of individuals in the probable and possible DLB groups was significantly higher in the group with glucose hypometabolism in the primary visual cortex.

CONCLUSION

Glucose hypometabolism in the primary visual cortex is commonly associated with the clinical features of DLB regardless of cognitive conditions. Continued follow-up of these patients without dementia with the metabolic pattern is warranted to determine if they represent the prodromal state of DLB.

Assessment of dementia risk in aging adults using both FDG-PET and FDDNP-PET imaging

BACKGROUND

In a previous study, positron emission tomography (PET) with 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile (FDDNP), a molecule that binds to plaques and tangles in vitro, identified three subgroups of non-demented subjects according to FDDNP binding patterns: low global (LG) binding; high frontal, parietal, medial temporal binding (HF/PA); and high medial and lateral temporal and posterior cingulate (HT/PC) binding. In this follow-up investigation, we compared 2-deoxy-2-[F-18]fluoro- d-glucose (FDG)-PET cerebral metabolic patterns in the three FDDNP-PET binding subgroups.

METHODS

Fifty-four subjects with normal aging (N = 28) or amnestic forms of mild cognitive impairment (N = 26) underwent FDDNP-PET and FDG-PET scanning. Subjects in the LG, HF/PA, and HT/PC FDDNP subgroups were compared according to visual ratings, statistical parametric mapping, and automated region of interest analyses of their FDG-PET data.

RESULTS

The FDDNP-PET subgroups demonstrated different glucose metabolic patterns according to visual ratings, region of interest, and statistical parametric mapping analyses of FDG-PET data. The LG FDDNP subgroup showed no areas of significant hypometabolism relative to the other subgroups and had low Alzheimer's disease risk by FDG-PET standards. The HF/PA FDDNP subgroup demonstrated hypometabolism in bilateral inferior parietal/parietotemporal, bilateral posterior cingulate, perisylvian, mid-temporal gyrus, and dorsolateral prefrontal regions, which is a pattern suggestive of high Alzheimer's disease risk. The HT/PC FDDNP subgroup demonstrated heterogeneous FDG-PET patterns with predominant anterior frontal and anterior temporal hypometabolism, suggestive of mixed etiologies, including fronto-temporal dementia risk.

CONCLUSIONS

The FDG-PET data provided independent validation that different patterns of FDDNP-PET binding in non-demented individuals may be associated with differential dementia risk.

Relative Function: Nuclear Brain Imaging in United States Courts

Neuropsychological testing—medical imaging of the brain structure and function—allows the expert to inform the court on the brain structure and function of the forensic examinee. Supported by extensive clinical use, neuropsychological testing and structural imaging in the form of computerized tomography and structural magnetic resonance imaging have achieved general acceptance in court. However, functional imaging such as functional MRI and nuclear medicine techniques, such as positron emission tomography (PET), have faced more admissibility challenges. While functional imaging is becoming an increasingly important tool in assessing neuropsychiatric illness, we surmise that evidentiary challenges are largely related to the phase of trial in which the nuclear study is offered as evidence. This article will review the basic science of functional nuclear imaging including PET and single photon emission computed tomography. We will then review cases where admissibility of these techniques has been challenged and consider whether and how nuclear brain imaging can influence the outcome of the trial.

Diffuse occipital hypometabolism on [18 F]-FDG PET scans in patients with idiopathic REM sleep behavior disorder: prodromal dementia with Lewy bodies?

BACKGROUND

Previous longitudinal studies have revealed that specific patterns on [(18) F]-fluoro-d-glucose (FDG) positron emission tomography (PET) scans in patients with amnesic mild cognitive impairment can predict Alzheimer's disease (AD). However, the significance of particular patterns on [(18) F]-FDG PET scans in prodromal patients with dementia with Lewy bodies (DLB) remains unclear.

METHODS

Based on the prevailing evidence that rapid eye movement (REM) sleep behavior disorder (RBD) often precedes the onset of DLB, [(18) F]-FDG PET scans of nine non-demented patients reporting recurrent nocturnal dream-enactment behavior in our memory clinic were compared with the normative database using three-dimensional stereotactic surface projection (3D-SSP) images. All patients underwent clinical and neuropsychological examinations as well as cardiac [(123) I]-metaiodobenzylguanidine ([(123) I]-MIBG) scintigraphy.

RESULTS

Four patients were found to have diffuse areas of reduced cerebral metabolic rate of glucose (CMRglc), predominantly in the occipital lobe, which is the preferentially affected region in DLB patients. In contrast, five patients showed no such occipital hypometabolism; instead, these five patients showed hypometabolism in the left anterior cingulate gyrus (Broadmann area (BA) 24), right frontal lobe (BA 32) and right anterior temporal lobe (BA 38), which are the preferentially affected regions in Parkinson's disease rather than DLB. The extent of the reduction in CMRglc in the left occipital lobe was correlated with scores on the Bender Gestalt Test, which reflects visuospatial ability, but not with global cognitive measures. All patients showed reduced cardiac [(123) I]-MIBG levels, consistent with underlying Lewy body disease.

CONCLUSION

These variations in [(18) F]-FDG PET scans raise the possibility that the specific pattern of CMRglc reduction may predict developing DLB in patients with idiopathic RBD. Further follow-up studies are needed, particularly on patients with diffuse occipital hypometabolism.