Magnetic resonance imaging differences between dementia with Lewy bodies and Alzheimer's disease: a pilot study

Neuroimaging in dementia and depression

Neuroimaging is traditionally divided into structural and functional imaging. Structural imaging looks at brain structure or anatomy and includes computed tomography (CT) and magnetic resonance imaging (MRI). Functional techniques seek to examine the physiological functioning of the brain, either at rest or during activation, and include single photon emission computed tomography (SPECT), positron emission tomography (PET), MRI spectroscopy, functional MRI (fMRI) and encephalographic brain mapping. Although fMRI, MRI spectroscopy and brain mapping are likely to have clinical applications in the near future, the main imaging modalities of current clinical relevance to psychiatrists are CT, MRI and SPECT, which will be the focus of this article.

Relationship between amygdala volume and emotion recognition in adolescents at ultra-high risk for psychosis

Amygdala volume has been proposed as a neural risk biomarker for psychotic illness, but findings in the ultra-high risk for psychosis (UHR) population have been somewhat inconsistent, which may be related to underlying social cognitive abilities. The current study investigated whether amygdala volumes were related to emotion-recognition impairments in UHR individuals, and whether volumes differed by sex. Secondary aims were to assess whether (a) emotion-recognition performance was associated with interhemispheric amygdala volume asymmetry and (b) amgydala volume and volume asymmetry acted as a mediator between emotion-recognition and outcome measures. The amygdala was manually delineated from magnetic resonance images for 39 UHR individuals who had also completed facial and prosody emotion-recognition tasks. Partial correlations were conducted to examine associations between amydgala volume/asymmetry and recognition of negative emotions. Mediation analyses were conducted using regression and bootstrapping techniques. Amygdala volume was positively correlated with sadness emotion recognition, in particular prosody, for females only. Left amygdala volume mediated the effect of sadness recognition on depressive symptoms, negative symptoms, overall psychopathology, and global functioning in females. Findings suggest a complex relationship between emotion recognition, the structure of the amygdala and illness outcome, where recognition of sadness appears to be the precipitator of this relationship in UHR females. Further research is needed to determine illness specificity and to confirm our sex- and emotion-specific results.

Pattern of brain atrophy rates in autopsy-confirmed dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is characterized by preserved whole brain and medial temporal lobe volumes compared with Alzheimer's disease dementia (AD) on magnetic resonance imaging. However, frequently coexistent AD-type pathology may influence the pattern of regional brain atrophy rates in DLB patients. We investigated the pattern and magnitude of the atrophy rates from 2 serial MRIs in autopsy-confirmed DLB patients (n = 20) and mixed DLB/AD patients (n = 22), compared with AD (n = 30) and elderly nondemented control subjects (n = 15), followed antemortem. DLB patients without significant AD-type pathology were characterized by lower global and regional rates of atrophy, similar to control subjects. The mixed DLB/AD patients displayed greater atrophy rates in the whole brain, temporoparietal cortices, hippocampus and amygdala, and ventricle expansion, similar to AD patients. In the DLB and DLB/AD patients, the atrophy rates correlated with Braak neurofibrillary tangle stage, cognitive decline, and progression of motor symptoms. Global and regional atrophy rates are associated with AD-type pathology in DLB, and these rates can be used as biomarkers of AD progression in patients with LB pathology.

Application of the VSRAD, a specific and sensitive voxel-based morphometry, to comparison of entorhinal cortex atrophy between dementia with Lewy bodies and Alzheimer's disease

BACKGROUND

Previous studies using magnetic resonance imaging (MRI) showed that dementia with Lewy bodies (DLB) had less atrophy in some medial temporal structures than Alzheimer's disease (AD). However, very few studies have focused on the entorhinal cortex, which is closely related to episodic memory. We compared the degree of entorhinal cortex atrophy between the two types of dementia using the voxel-based specific regional analysis system for AD (VSRAD) targeting this region.

METHODS

The subjects consisted of 60 patients with DLB and 210 patients with AD. The degree of entorhinal cortex atrophy was quantified by application of the VSRAD to MRI data, and a Z score >2 was defined as significant atrophy.

RESULTS

The DLB group had significantly lower Z scores than the AD group (mean ± SD: 2.25 ± 1.10 vs. 2.85 ± 1.33, p < 0.01). The analysis of covariance with possible confounding factors as covariates also showed that Z scores were significantly lower in the DLB group than in the AD group (p < 0.01). The proportion of patients with atrophy was significantly lower in the DLB group than in the AD group (53 vs. 72%, p < 0.01).

CONCLUSIONS

The present study using the VSRAD suggests that DLB shows less atrophy in the entorhinal cortex than AD.

Differentiating dementia with Lewy bodies and Alzheimer’s disease using MRI

SUMMARY Despite the characteristic clinical differences between dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD), a large degree of overlap exists. In particular, the clinical diagnostic criteria for DLB lack sensitivity so that many cases of DLB will be missed during life. MRI techniques offer a noninvasive method to assess the brain structure and function in more detail. In particular, advanced MRI methods such as diffusion-tensor imaging, functional MRI, arterial spin labeling (perfusion) and magnetic resonance spectroscopy may offer more sensitive methods to detect early and, possibly, preclinical change in dementia and contribute to our understanding of the differences between AD and DLB. This paper provides an overview of MRI changes in DLB and AD, the relationship to other imaging modalities such as single-photon emission computed tomography and PET, highlighting the differences between the conditions currently applicable to the clinical setting, as well as recent developments in MRI methods yet to be translated into large-scale clinical studies.

Measurement of gray and white matter atrophy in dementia with Lewy bodies using diffeomorphic anatomic registration through exponentiated lie algebra: A comparison with conventional voxel-based morphometry

BACKGROUND AND PURPOSE

DLB is recognized as the second major form of dementia in the elderly. The regional pattern of GM atrophy in DLB highly overlaps that in AD. The aim of this study was to identify the critical pattern of atrophy in DLB by using DARTEL, which provides improved registration accuracy compared with that of conventional VBM.

MATERIALS AND METHODS

We evaluated 51 patients with probable AD, 43 patients with probable DLB, and 40 age-matched healthy controls. The pattern of GM atrophy in each group was compared by using conventional VBM and VBM-DARTEL.

RESULTS

Regional patterns of atrophy identified by using conventional VBM differed significantly from those identified by using VBM-DARTEL. A decrease in GM volume in the MTLs in both AD and DLB was identified with VBM-DARTEL; the decrease was greater in patients with AD than in those with DLB. Comparisons with healthy controls revealed that the WM volume of the whole brain was preserved in patients with DLB. In contrast, a severe bilateral decrease in WM in the MTLs was detected in patients with AD.

CONCLUSIONS

VBM-DARTEL provided more accurate results, and it enabled the identification of more localized morphologic alterations than did conventional VBM. Analysis of WM preservation in DLB could help to differentiate this condition from AD.

Rates of cerebral atrophy differ in different degenerative pathologies

Neurodegenerative disorders are pathologically characterized by the deposition of abnormal proteins in the brain. It is likely that future treatment trials will target the underlying protein biochemistry and it is therefore increasingly important to be able to distinguish between different pathologies during life. The aim of this study was to determine whether rates of brain atrophy differ in neurodegenerative dementias that vary by pathological diagnoses and characteristic protein biochemistry. Fifty-six autopsied subjects were identified with a clinical diagnosis of dementia and two serial head MRI. Subjects were subdivided based on pathological diagnoses into Alzheimer's disease, dementia with Lewy bodies (DLB), mixed Alzheimer's disease/DLB, frontotemporal lobar degeneration with ubiquitin-only-immunoreactive changes (FTLD-U), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). Twenty-five controls were matched by age, gender and scan interval, to the study cohort. The boundary-shift integral was used to calculate change over time in whole brain (BBSI) and ventricular volume (VBSI). All BSI results were annualized by adjusting for scan interval. The rates of whole brain atrophy and ventricular expansion were significantly increased compared to controls in the Alzheimer's disease, mixed Alzheimer's disease/DLB, FTLD-U, CBD and PSP groups. However, atrophy rates in the DLB group were not significantly different from control rates of atrophy. The largest rates of atrophy were observed in the CBD group which had a BBSI of 2.3% and VBSI of 16.2%. The CBD group had significantly greater rates of BBSI and VBSI than the DLB, mixed Alzheimer's disease/DLB, Alzheimer's disease and PSP groups, with a similar trend observed when compared to the FTLD-U group. The FTLD-U group showed the next largest rates with a BBSI of 1.7% and VBSI of 9.6% which were both significantly greater than the DLB group. There was no significant difference in the rates of atrophy between the Alzheimer's disease, mixed Alzheimer's disease/DLB and PSP groups, which all showed similar rates of atrophy; BBSI of 1.1, 1.3 and 1.0% and VBSI of 8.3, 7.2 and 10.9%, respectively. Rates of atrophy therefore differ according to the pathological diagnoses and underlying protein biochemistry. While rates are unlikely to be useful in differentiating Alzheimer's disease from cases with mixed Alzheimer's disease/DLB pathology, they demonstrate important pathophysiological differences between DLB and those with mixed Alzheimer's disease/DLB and Alzheimer's disease pathology, and between those with CBD and PSP pathology.

Tracking Alzheimer's disease

Population-based brain mapping provides great insight into the trajectory of aging and dementia, as well as brain changes that normally occur over the human life span. We describe three novel brain mapping techniques, cortical thickness mapping, tensor-based morphometry (TBM), and hippocampal surface modeling, which offer enormous power for measuring disease progression in drug trials, and shed light on the neuroscience of brain degeneration in Alzheimer's disease (AD) and mild cognitive impairment (MCI). We report the first time-lapse maps of cortical atrophy spreading dynamically in the living brain, based on averaging data from populations of subjects with Alzheimer's disease and normal subjects imaged longitudinally with MRI. These dynamic sequences show a rapidly advancing wave of cortical atrophy sweeping from limbic and temporal cortices into higher-order association and ultimately primary sensorimotor areas, in a pattern that correlates with cognitive decline. A complementary technique, TBM, reveals the 3D profile of atrophic rates, at each point in the brain. A third technique, hippocampal surface modeling, plots the profile of shape alterations across the hippocampal surface. The three techniques provide moderate to highly automated analyses of images, have been validated on hundreds of scans, and are sensitive to clinically relevant changes in individual patients and groups undergoing different drug treatments. We compare time-lapse maps of AD, MCI, and other dementias, correlate these changes with cognition, and relate them to similar time-lapse maps of childhood development, schizophrenia, and HIV-associated brain degeneration. Strengths and weaknesses of these different imaging measures for basic neuroscience and drug trials are discussed.

Differences in magnetization transfer ratios of the hippocampus between dementia with Lewy bodies and Alzheimer's disease

We compared magnetization transfer ratios (MTRs) in the brains of patients with dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) to determine whether regional differences in the brain structures between DLB and AD are detectable with magnetization transfer imaging. Seventeen patients with DLB, 31 patients with AD and 18 elderly normal controls were included. Although no significant differences were found in MTRs in the frontal white matter between the three groups, MTRs in the hippocampus, parahippocampus, and posterior cingulate white matter in both patients with DLB and AD were significantly lower than those in age-matched control subjects. However, MTRs in the hippocampus of patients with DLB were significantly higher than those in patients with AD. Logistic regression analysis revealed that hippocampal MTR yielded a sensitivity of 76% and a specificity of 71% in discriminating DLB from AD. These results may reflect underlying histopathological differences with less severe neuronal degeneration in the hippocampus of DLB. MTR measurement of the hippocampus may contribute to the clinical differentiation between DLB and AD.

The clinical utility of structural neuroimaging with MRI for diagnosis and differential diagnosis of dementia: a memory clinic study

OBJECTIVES

The individual contribution to the final comprehensive clinical diagnosis of neuropsychology (NP) and magnetic resonance imaging (MRI), respectively, was quantified in a specialized tertiary care setting to investigate the added clinical value of routine MRI.

METHODS

In 106 patients referred to a university memory clinic for the work-up of cognitive disturbances the primary care diagnosis, the initial clinical neuropsychiatric diagnosis, the neuropsychological and MRI diagnoses, and the final comprehensive clinical diagnosis were documented. The neuropsychological investigation was performed using the CERAD test battery. MRI was performed using T1, double echo and FLAIR sequences without contrast medium. The change of the final comprehensive clinical diagnosis in relation to the initial neuropsychiatric diagnosis was used to determine the diagnostic contribution of both, MRI and NP.

RESULTS

NP and MRI led to a significant change of the final comprehensive diagnosis in 26% of patients (CI: 0.26 +/- 0.09; p < 0.05). In addition, three cases of secondary dementias, and six cases of vascular encephalopathy without dementia were recognized by MRI. Sensitivity, specificity, and the positive predictive value were higher for NP and MRI, respectively, than for the initial clinical diagnosis alone.

CONCLUSION

MRI as well as neuropsychological testing improves early detection and differential diagnosis of dementia and additionally supplies clinically relevant findings. MRI carries added clinical value in the investigation of dementias.

Diagnosis of dementia with Lewy bodies in clinical practice: a literature review

OBJECTIVE

To review the research data about dementia with Lewy bodies (DLB) and describe those clinical features and investigations that will enhance more accurate diagnosis in day-to-day practice.

METHODS

A literature search using MEDLINE, Psychlit, Psychinfo and Cochrane databases was performed.

CONCLUSIONS

The diagnosis of DLB is important now that treatment is available using cognitive enhancers and because of the risk to patients with DLB who are prescribed neuroleptics. The use of consensus criteria, despite their limitations, and judicious use of ancillary investigations, especially neuroimaging and neuropsychological tests, will enhance diagnostic accuracy.

Comparing gray matter loss profiles between dementia with Lewy bodies and Alzheimer's disease using cortical pattern matching: diagnosis and gender effects

We used magnetic resonance imaging (MRI) and cortical pattern matching to map differences in cortical gray matter deficits between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), and explored the possible influence of gender on these patterns. Twenty-nine patients with AD (age 77.9 +/- 5.5), 16 patients with DLB (76.4 +/- 6.7), and 38 controls (75.3 +/- 6.8) were included. Dementia groups were matched for illness severity. Detailed spatial analyses of gray matter were conducted across the entire cerebral cortex by measuring local proportions of gray matter at thousands of homologous cortical surface locations in each subject and between diagnostic groups. To visualize regional changes, statistical differences were mapped at each cortical surface location in 3D. Main effects of diagnosis demonstrated prominent gray matter differences in orbitofrontal and temporal cortices, where AD exhibited the greatest deficits relative to DLB. Main effects of sex showed less gray matter in men within all group comparisons. Exploratory findings for sex by diagnosis interactions suggest greater gray matter loss in the anterior cingulate for men with AD, relative to controls, AD females, and individuals with DLB. Relative preservation of orbitofrontal cortices in addition to temporal structures may contribute to distinguishing DLB from AD. Further investigation of the influence of gender might provide a more comprehensive understanding of the pathophysiological differences underlying the two forms of dementia.

Basal forebrain atrophy is a distinctive pattern in dementia with Lewy bodies

We determined brain atrophy patterns in dementia with Lewy bodies and Alzheimer's disease using voxel-based morphometry, an indirect volumetry. Ten patients with dementia with Lewy bodies, 10 patients with Alzheimer's disease and 10 controls were included. All groups were matched for age; sex and global differences in voxel intensities were included as confounding covariates. We observed basal forebrain atrophy discriminating dementia with Lewy bodies from Alzheimer's disease. Compared to controls, atrophy of lateral prefrontal cortex and left premotor cortex was seen in dementia with Lewy bodies whereas atrophy of the medial temporal cortex, posterior parietal cortex, thalamus and temporo-occipital areas was observed in Alzheimer's disease. Atrophy of insular cortex was found in both patient groups.

Are Parkinson's disease with dementia and dementia with Lewy bodies the same entity?

The diagnosis of Parkinson's disease with dementia (PDD) or dementia with Lewy bodies (DLB) is based on an arbitary distinction between the time of onset of motor and cognitive symptoms. These syndromes share many neurobiological similarities, but there are also differences. Deposition of beta-amyloid protein is more marked and more closely related to cognitive impairment in DLB than PDD, possibly contributing to dementia at onset. The relatively more severe executive impairment in DLB than PDD may relate to the loss of frontohippocampal projections in DLB. Visual hallucinations and delusions associate with more abundant Lewy body pathology in temporal cortex in DLB. The differential involvement of pathology in the striatum may account for the differences in parkinsonism. Longitudinal studies with neuropathological and neurochemical evaluations will be essential to enable more robust comparisons and determine pathological substrates contributing to the differences in cognitive, motor, and psychiatric symptoms.

Progress in clinical neurosciences: Parkinson's disease with dementia and dementia with Lewy bodies

Dementia occurs in up to 30% of people with Parkinson's disease and is a major cause of disability. Pathologically, Parkinson's dementia, where dementia follows the onset of parkinsonism by at least one year, overlaps with dementia with Lewy bodies. We review the functional impact, definitions, neuropsychology, epidemiology and pathophysiology of Parkinson's dementia, dementia with Lewy bodies and their overlap. Associated psychiatric and imaging findings are also considered. Lastly, current and emerging approaches to assessment and treatment in patients with these Lewy body associated dementias are presented.

Parkinson's disease is associated with hippocampal atrophy

Patients with Parkinson's disease (PD) may have hippocampal atrophy compared with controls. We compared hippocampal, and extra-hippocampal volumes between PD, PDD (patients with PD who have mild cognitive impairment or dementia), Alzheimer's disease (AD) and controls using volumetric magnetic resonance imaging (MRI). Participants (10 patients with PD, 10 with PDD, 11 with AD, and 12 control subjects) had an informant interview, neurological examination, and psychometric testing. Established, reliable methods were used to measure the hippocampus, parahippocampal gyrus, temporal, frontal, and parieto-occipital lobes. Correction for intracranial volume was carried out before comparison. There was no age difference between groups (mean age, 74 years). On the Clinical Dementia Rating scale (CDR) cognitive impairment was mild (CDR = 0.5) in the majority of PDD and AD patients. Hippocampal (P < 0.0004) volumes were smaller in the patient groups. Effect sizes compared with the control group were: PD, 0.66; PDD, 1.22; and AD, 1.81. The other volumes did not differ significantly. Among PD and PDD patients, recognition memory (r = 0.54, P = 0.015) and Mini-Mental State Examination scores (r = 0.56, P = 0.01) correlated with left, but not right hippocampal volume. In conclusion, hippocampal volume showed a pattern (Control > PD > PDD > AD) suggesting progressive hippocampal volume loss in PD. Volumetric MRI imaging might provide an early marker for dementia in PD.

Neuroimaging in dementia with Lewy bodies: metabolism, neurochemistry, and morphology

Dementia with Lewy bodies (DLB) is recognized as one of the most common forms of neurodegenerative dementia. Neuroimaging contributes to a better understanding of the pathophysiology of DLB by examining alterations in brain metabolism, neurochemisty, and morphology in living patients. Neuroimaging can provide objective and quantifiable antemortem markers for the presence of and the progression of DLB and permits differentiation from other dementias. This article reviews current neuroimaging findings in DLB with particular attention to occipital hypometabolism, dopaminergic and cholinergic deficits, and medial temporal lobe atrophy as measured by positron emission tomography, single-photon emission computed tomography, and magnetic resonance imaging.

Magnetic resonance imaging, Down's syndrome and Alzheimer's disease: research and clinical implications

BACKGROUND

The diagnosis of Alzheimer's disease (AD) remains at times difficult to make using available neuropsychological measures. Neuro-imaging is a relatively new form of detecting the changes associated with dementia. The present study investigated the role of magnetic resonance imaging (MRI) in diagnosing AD in adults with Down's syndrome (DS).

METHODS

Subjects with DS and Alzheimer-type dementia were matched to non-demented controls with DS. Magnetic resonance imaging findings (i.e. volumetric and two-dimensional scans) were compared between the two groups in order to show a relationship between the changes of AD and structural MRI abnormalities.

RESULTS

Specific structural abnormalities which are seen in non-intellectually disabled subjects with dementia are also found in individuals with both DS and AD. However, such findings cannot be used to diagnose clinical AD with good accuracy in adults with DS. A number of practical issues of patient compliance and over-sedation are demonstrated by the findings.

CONCLUSIONS

Magnetic resonance imaging has an important but limited role to play in the management of AD in the population with DS. If intravenous sedation is used, medical support is essential to prevent a serious mishap.

Patterns of cerebral atrophy in dementia with Lewy bodies using voxel-based morphometry

Previous cross-sectional MRI studies based on region-of-interest analyses have shown that increased cerebral atrophy is a feature of both Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Relative preservation of the hippocampus and temporal lobe structures in DLB compared to AD has been reported in region-of-interest-based studies. Recently, image processing techniques such as voxel-based morphometry (VBM) have been developed to provide an unbiased, visually informative, and comprehensive means of studying patterns of cerebral atrophy. We report the first study to use the voxel-based approach to assess patterns of cerebral atrophy in DLB compared to control subjects and AD. Regional gray matter volume loss was observed bilaterally in the temporal and frontal lobes and insular cortex of patients with DLB compared to control subjects. Comparison of dementia groups showed preservation of the medial temporal lobe, hippocampus, and amygdala in DLB relative to AD. Significant gray matter loss was also observed in the thalamus of AD patients compared to DLB.

The Mini-Mental State exam may help in the differentiation of dementia with Lewy bodies and Alzheimer's disease

OBJECTIVE

Since patients with dementia with Lewy bodies (DLB) tend to have greater impairment of attention and construction and better memory ability on neuropsychological tests than patients with Alzheimer's disease (AD), we determined if the items that measure attention, memory, and construction in the Mini-Mental State Examination (MMSE) help to distinguish DLB from AD early in the course of the dementia.

DESIGN

We retrospectively studied the first available MMSE exam for each of our patients with DLB or AD and compared their MMSE subscores for attention, memory, and construction.

SETTING

A university dementia brain bank in central Illinois, USA.

PATIENTS

All patients with neuropathologically-proven DLB or AD with MMSE scores > or =13.

RESULTS

We identified 17 DLB and 27 AD patients for whom we had MMSE exams. The attention and construction subtest scores of the DLB group were worse (p=0.0071 and p=0.0038, respectively) than those of the AD group. The memory subscores of the DLB group were better, although the difference did not reach statistical significance (p=0.22). When a mathematical equation was used to combine the three subscores with equal weighting (Attention-5/3Memory+5.Construction), the scores of the DLB group were worse (p=0.00007). Using this equation, a score less than 5 points was associated with DLB with a sensitivity of 0.82 (95% Confidence Interval (CI)=0.57-0.96) and a specificity of 0.81 (95% CI=0.62-0.94).

CONCLUSIONS

Our findings support the work of others regarding the relative neuropsychological impairments of DLB and AD and indicate that the MMSE may be helpful in the differentiation of DLB and AD.

Dementia with Lewy bodies

DLB is a complex disorder with important associations with PD and AD. As clinicians, it is important for us to identify these patients because of their unique responses to medical interventions and to help patients and caregivers more fully understand this disease process and its implications. Further research is needed to improve our understanding of the pathophysiology of this important dementing disorder, with the ultimate goal of improving clinical management of this disease.

Brain volume, intracranial volume, and dementia

RATIONALE AND OBJECTIVES

Using a large magnetic resonance (MR) imaging data set (n = 532), we investigated the utility of total intracranial volume (TICV) as a correction factor for head size variability when assessing total brain volume (TBV) and the subcortical volumes of the temporal horn of the lateral ventricular system and the hippocampus.

METHODS

A uniform tissue segmentation procedure (analyze) was used to calculate volumes. Total brain volume was compared with TICV in 357 control subjects and 175 patients with various dementing and neuropsychiatric disorders (mixed dementia/neuropsychiatric group). These MR-based TBV/TICV relationships were compared with actual postmortem (n = 87) values obtained from a study of neurologically healthy subjects at the time of death. Comparisons were also made in which temporal horn and hippocampal volumes were corrected by TICV and TBV. Lastly, the ability of corrected TBV and temporal horn and hippocampal volumes to distinguish subjects in the mixed dementia/neuropsychiatric group from controls was examined by logistic regression.

RESULTS

In the control sample, brain volume averaged 9% of TICV, regardless of age. In contrast, TBV in the mixed dementia/neuropsychiatric subjects showed, on average, a 22% reduction compared with TICV. By plotting TBV/TICV curves, highly significant but different regression lines emerged, wherein a reduction in brain volume in conditions of mixed dementia/neuropsychiatric disorder showed a distinct separation from the norm. The TBV/TICV regression line generated from MR imaging in controls did not differ from the postmortem TBV/TICV regression line. Logistic regression showed a 96% correct classification of mixed dementia/neuropsychiatric subjects from controls by using the TBV/TICV ratio. This technique has the advantage that each subject serves as his or her own control.

CONCLUSIONS

In cases of dementia and neuropsychiatric disorder in persons 65 and older, TBV corrected by TICV readily differentiated this clinical population from controls. This technique is easy and simple to use and has various clinical applications. For temporal horn and hippocampal volume, corrections with TBV rather than TICV may provide more clinically meaningful corrections.

A comparison of medial and lateral temporal lobe atrophy in dementia with Lewy bodies and Alzheimer's disease: magnetic resonance imaging volumetric study

OBJECTIVES

To compare medial and lateral temporal lobe atrophy on magnetic resonance imaging (MRI) in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD), and to examine the relationship between volumetric indices and cognitive and non-cognitive symptoms.

METHODS

T(1)-weighted 1.0-tesla MRI scans were acquired in elderly subjects with DLB (n = 26; mean age = 75.8 years) and AD (n = 22; 77.3 years) and normal controls (n = 26; 76.2 years). MRI-based volume measurements of the hippocampus, parahippocampus, fusiform gyrus, combined inferior and middle temporal gyri, and superior temporal gyrus were acquired.

RESULTS

Hippocampal and parahippocampal volumes were significantly larger in subjects with DLB compared to AD. Differences in hippocampal volumes between DLB and AD were observed across the entire length, and in all subjects with dementia there was a loss of hippocampal asymmetry compared to normal controls. Atrophy of temporal lobe structures correlated with memory impairment in both groups, and with age in DLB. There was no association between atrophy and psychotic symptoms in either group.

CONCLUSIONS

Subjects with DLB and AD have a different pattern of temporal lobe atrophy with the most striking differences relating to medial rather than lateral temporal lobe structures. These structural differences could explain the relative preservation of memory function in DLB compared to AD.

Magnetic resonance imaging and magnetic resonance spectroscopy in dementias

This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect.

Medial temporal lobe width on CT scanning in Alzheimer's disease: comparison with vascular dementia, depression and dementia with Lewy bodies

A simple linear measurement of the minimum width of the medial temporal lobe (MTL) on angled CT scans has been suggested as an accurate ante-mortem marker for Alzheimer's disease (AD). To determine the clinical utility and specificity of this finding, we performed angled CT scans with 5-mm slices in 116 subjects referred to a geographically based Old Age Psychiatry service in Newcastle. Diagnoses were of NINCDS/ADRDA AD (n = 69, 36 probable and 33 possible). NINDS/AIREN vascular dementia (VaD, n = 25), consensus criteria for dementia with Lewy bodies (DLB, n = 9) and DSM-IV criteria for major depression (n = 13). Subjects were well matched for age. Minimum MTL width was significantly greater in depressed subjects (13.7 mm) compared to those with dementia, though no differences were seen within the dementia groups (AD 10.8, VaD 10.4, and DLB 10.9 mm). An MTL width below 11.5 mm had a sensitivity of 54% (56/103) and a specificity of 77% (10/13) for distinguishing dementia from depression. We conclude that a single cross-sectional measurement of MTL width on CT does not help differentiate between different types of dementia, though it may provide some supportive evidence when distinguishing depression from dementia.

Dementia with Lewy bodies

OBJECTIVE

The aim of this paper is to summarise recent clinical and research findings with regard to dementia with Lewy bodies (DLB).

METHOD

A literature review (Medline) was carried out, as well as a review of reports of recent DLB symposia of international meetings and of other relevant papers and data known to the authors.

RESULTS

Dementia with Lewy bodies, as the disorder should be known, is the second commonest form of degenerative dementia, accounting for up to 20% cases in the elderly. It is characterised by fluctuating cognitive impairment, spontaneous parkinsonism and recurrent visual hallucinations. Consensus clinical and neuropathological criteria have been published. The clinical criteria have been shown to have high specificity, but may still lack sensitivity. Recognition of DLB is clinically important in view of the high incidence (60%) of adverse and life-threatening reaction to antipsychotics, the difference in prognosis and, possibly, the differential treatment response to cholinergic therapy. Neuroimaging changes have not been well described in DLB but some show promise as potential markers to differentiate DLB from AD. These include relative preservation of temporal lobe structures on magnetic resonance imaging and loss of pre- and postsynaptic dopaminergic markers on single photon emission tomography.

CONCLUSIONS

Dementia with Lewy bodies is a common cause of cognitive impairment in late life which appears to be clinically and neuropathologically distinct from AD. All clinicians should be aware of the typical triad of clinical features (fluctuating cognitive impairment, visual hallucinations and parkinsonism) which characterise the disorder and either avoid antipsychotics or prescribe them with extreme caution in such patients. Further research is likely to result in advances in diagnostic methods and therapeutics in the near future.

Recent advances in atypical parkinsonian disorders

Recent advances in epidemiologic, diagnostic, pathologic, and management aspects of atypical parkinsonian disorders are reviewed and placed in perspective. The implications of considering progressive supranuclear palsy and corticobasal degeneration as tauopathies, and multiple system atrophy and dementia with Lewy bodies as alpha-synucleopathies are discussed.