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

The role of brain structural magnetic resonance imaging in the assessment of hippocampal subfields in Alzheimer’s disease

Background

Volumetric MR neuroimaging can visualize the pattern of hippocampal subfield atrophic changes in AD. This can be used as a biomarker in early diagnosis of AD and allow early treatment to improve memory, behavioral symptoms, and delay the cognitive deterioration. The aim of this work is to assess the role of the volumetric study of different hippocampal subfields as a post-processing technique of structural MR imaging in patients with Alzheimer’s disease of different severity of cognitive functions. The regional ethics committee approved the study and written informed consent was obtained from all participants. In the duration from 2016 to 2018, a cross-sectional study was conducted on 30 patients (17 males and 13 females) and 15 healthy elderly controls (9 males and 6 females) referred to the Radiodiagnosis Department from the Neuropsychiatry Department. Patients were diagnosed with AD by clinical examination and using the Mini Mental State Examination (MMSE) and the Clinical Dementia Rating scale (CDR) as a measure of general cognitive performance.

Results

CA1 and subiculum subfields were significantly reduced in size in patients with Alzheimer’s disease in relation to the age-matched control group (P < 0.05). This finding was positively correlated with the MMSE score and negatively correlated with CDR clinical tests. No significant atrophy was found among other hippocampal subfields in the patients’ group.

Conclusion

This study proposed a new approach to detect atrophy in hippocampal subfields, using MR volumetric study of high-resolution T1 images, that can be used as a biomarker in the diagnosis of AD patients and differentiating them from elderly control subjects which is important in early diagnosis of AD and hence the proper treatment to improve the prognosis of the cognitive function.

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.

Prevalence of depression among memory clinic patients as measured by the Cornell Scale of Depression in Dementia

OBJECTIVES

Depression in dementia is common, but the prevalence rates differ according to the populations studied and which diagnostic tools are being used. The aim of this study is to explore the prevalence of depression among patients referred to a memory clinic or an outpatient clinic as measured by the Cornell Scale of Depression in dementia (CSDD) and to investigate which factors are associated with depression.

METHOD

The CSDD was completed for 1470 patients on their first visit to a memory clinic or an outpatient clinic. The prevalence of depression using three different cut-off points was calculated. Logistic regression and correlation analyses were performed.

RESULTS

Half of the patients had dementia. The mean CSDD was 6.7 (SD: 5.3) for the whole group, and 50.2% had a score above 5, whereas 37.5% had depression defined as a CSDD score above 7, and 14.1% had a score above 12. The mean scores were higher among those with dementia other than Alzheimer's disease, those with previous depression, and those with greater impairment in the activities of daily living (ADL). In the logistic regression analyses, younger age, ADL dysfunction, and previous depression were significantly associated with higher CSDD scores.

CONCLUSION

We found that depressive symptoms are common among patients referred for a dementia assessment in specialist health care. The strongest factors associated with depressive symptoms were younger age, ADL impairment, and previous depression.

The use of CT in dementia

Neuroimaging has become part of the required investigations when assessing a patient with dementia. In this brief paper, we summarize the role of computed tomography (CT) in the routine work-up in dementia and provide some information about the role of the CT scan in the field of dementia research. Although CT is far less sensitive than magnetic resonance imaging (MRI) in detecting changes associated with cognitive impairment, it may still have a role in this regard. This role is mainly that of detecting secondary, sometimes treatable causes of cognitive impairment, such as intracranial masses. In this sense, CT should be seen as a first-line tool. Possible advantages of CT are lower cost; shorter acquisition time, making it more adaptable to patients with poor compliance; and the possibility that it can be performed in patients with metal devices, such as a pacemaker. The role of CT in the field of dementia research is very restricted in comparison to that of MRI, and is limited to the structural assessment of vascular lesions, and to a lesser extent, to that of degenerative changes, particularly when using specific slicing.

Role of imaging techniques in the diagnosis of dementia

Dementia is a common and growing problem, affecting 5% of the over 65 s and 20% of the over 80s. The recent availability of new treatments for dementia, as well as the importance of subtype-specific management, has renewed interest in the use of brain imaging techniques that can assist in the accurate recognition of Alzheimer's disease (AD), dementia with Lewy bodies (DLB), vascular dementia (VaD) and frontotemporal dementia (FTD). Structural imaging, historically used to exclude an intracerebral lesion as a cause for dementia, is increasingly playing a role in "ruling in" diagnoses, with atrophy of the hippocampus and entorhinal cortex an early and sensitive marker for AD, and cortical and subcortical infarcts and white matter lesions characteristic of VaD. Regionally distinct patterns of hypoperfusion on single-photon emission computed tomography (SPECT) or hypometabolism on positron emission tomography (PET) can help differentiate FTD, AD and VaD, and dopaminergic loss in the basal ganglia can differentiate DLB from AD. Newer techniques show great promise to detect specific neuroreceptor changes as well as pathological underpinnings of dementia, such as amyloid and tau pathology.

Is there any role for computed tomography measurements of medial temporal lobe atrophy in dementia? A review of the literature and case series from a memory clinic

Neuroimaging in dementia has focused on documenting any burden of vascular disease or excluding any reversible intracranial pathology. We review the use of computed tomography to examine for medial temporal lobe atrophy in dementia and compare this with a case series of such measurements from our memory clinic. Measures of medial temporal lobe atrophy were used to separate patients with Alzheimer's disease from those with normal cognition, mood disorders or other forms of early dementia.

Evidence-based evaluation of magnetic resonance imaging as a diagnostic tool in dementia workup

BACKGROUND

The diagnostic utility of magnetic resonance imaging in dementia workups has increased recently. The basic use is to exclude space-occupying processes in the brain. However, magnetic resonance imaging offers major opportunities for studying atrophy of specific brain areas. A great interest has been put in whether atrophy in the medial temporal lobe can serve as an early diagnostic marker for Alzheimer disease.

METHODS AND RESULTS

In this evaluation, we used evidence-based techniques and reviewed more than 400 articles that address this issue. Our main finding is that a variety of methods in studying brain areas were used, and this made it difficult to extract conclusive information in a systematic way.

CONCLUSION

However, we were able to conclude that atrophy of the hippocampus can distinguish patients with Alzheimer disease from healthy subjects, but there was a lack of evidence because of insufficient studies concerning the usefulness of medial temporal lobe atrophy as a diagnostic marker in a more general setting.

La lunga attesa: towards a molecular approach to neuroimaging and therapeutics in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, neurofibrillary tangles (NFT), synaptic loss and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography (CT) and magnetic resonance imaging (MRI) is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single photon emission computed tomography (SPECT), possibly in conjuction with other related Aβ biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the Aβ amyloid burden in the brain, there is increasing interest in the development of MRI contrast agents and PET and SPECT radioligands that will permit the assessment of Aβ amyloid burden in vivo. - ma dov'è / la lenta processione di stagioni / che fu un'alba infinita e senza strade, / dov'è la lunga attesa e qual è il nome / del vuoto che ci invade. - Eugenio Montale.

Association of minimal thickness of the medial temporal lobe with hippocampal volume, maximal and minimal hippocampal length: volumetric approach with horizontal magnetic resonance imaging scans for evaluation of a diagnostic marker for neuroimaging of Alzheimer's disease

A 3-D volumetric study of the medial temporal lobe (MTL) was performed to evaluate how a minimum thickness of the MTL (mtMTL), a visually estimated measure, is associated with other MTL measures, maximal and minimal hippocampal length (max-HL, min-HL) and hippocampal volume, all measured with a 3-D device, Neurolucida, in 33 patients with Alzheimer's disease (AD), seven patients with mild cognitive impairment (MCI), and 20 age-matched controls. Cognitive impairment was evaluated with Mini-Mental State examination (MMSE). The T1-weighted horizontal magnetic resonance imaging (MRI) scans with slices 5 mm thick were analyzed with Neurolucida and the mtMTL was measured with visual estimation. The MTL was divided into the amygdala and hippocampus. Max-HL on both sides was longer in controls than in AD and MCI, whereas min-HL and mtMTL were longer in controls than in AD, and no difference was observed between MCI and controls. Similarly hippocampal volume was larger in controls than in AD, and no differences were seen within the MCI and controls. No difference in amygdala and midbrain volumes was observed among AD, MCI and controls. Correlation of MMSE score with min-HL and mtMTL was higher than that with max-HL. Although hippocampal and MTL measures examined here failed to show significant difference between AD and MCI, max-HL could be a diagnostic neuroimaging sign of AD. The high correlation of MMSE with mtMTL as well as with min-HL compared with that with max-HL, also will support neuroimaging diagnosis of AD.

Imaginem oblivionis: the prospects of neuroimaging for early detection of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are A beta amyloid plaques, neurofibrillary tangles, and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the A beta amyloid burden in the brain, there is increasing interest in the development of PET and SPECT radioligands that will permit the assessment of A beta amyloid burden in vivo. From this, the prospect of specific preclinical diagnosis arises, possibly in conjunction with other related A beta biomarkers in plasma and CSF.

Grouping for behavioral and psychological symptoms in dementia: clinical and biological aspects. Consensus paper of the European Alzheimer disease consortium

Behavioral and psychological symptoms of dementia (BPSD), constitute a major clinical component of Alzheimer's disease (AD). There is a growing interest in BPSD as they are responsible for a large share of the suffering of patients and caregivers, and they strongly determine the patient's lifestyle and management. Better detection and understanding of these symptoms is essential to provide appropriate management. This article is a consensus produced by the behavioral group of the European Alzheimer's Disease Consortium (EADC). The aim of this article is to present clinical description and biological correlates of the major behavioral and psychological symptomatology in AD. BPSD is not a unitary concept. Instead, it should be divided into several symptoms or more likely: groups of symptoms, each possibly reflecting a different prevalence, course over time, biological correlate and psychosocial determinants. There is some clinical evidence for clusters within groups of BPSD. Biological studies indicate that patients with AD and BPSD are associated with variations in the pathological features (atrophy, brain perfusion/metabolism, histopathology) when compared to people with AD without BPSD. An individually tailored approach taking all these aspects into account is warranted as it may offer more, and better, pharmacological and non-pharmacological treatment opportunities.

Neuroimaging as a diagnostic tool in dementia with Lewy bodies

Due to similar presenting symptoms, many physicians find it difficult to distinguish cases of dementia with Lewy bodies (DLB) from Alzheimer's disease or Parkinson's disease with dementia. The pathologic diagnosis of DLB has improved because of the discovery of probes for alpha-synuclein, a protein found in Lewy bodies. However, pathologic diagnosis can be employed postmortem only, and therefore diagnostic techniques that can be employed to guide patient management are still needed. Consensus criteria have been developed for establishing a clinical diagnosis of DLB, but they lack sensitivity. Therefore, a review of the recent literature was conducted to establish whether neuroimaging studies are useful diagnostic tools to help differentiate these syndromes. At least six types of tests can be used to image the brain of patients with dementia. Structural studies (x-ray, magnetic resonance imaging and computerized tomography) can disclose the presence of stroke sequelae and other lesions, whereas functional studies (magnetic resonance spectroscopy, positron emission tomography and single-photon emission computed tomography) can disclose metabolic and blood flow alterations that may be characteristic for different types of dementia. Although more formal studies are needed to confirm that these imaging techniques are reliable diagnostic tools for DLB and permit the establishment of guidelines for their use, neuroimaging techniques currently are being employed in practice to differentiate dementia types as a guide to treatment.

Linear width of the medial temporal lobe can discriminate Alzheimer’s disease from normal aging: the Sunnybrook Dementia Study

To discriminate Alzheimer's disease (AD) from healthy controls, the thinnest medial temporal lobe (tMTL) width on 3D-MRI was measured according to a newly developed method at the inter-collicular sulcus (ICS) level with scans aligned to the long axis of the hippocampus in 22 mild, 27 moderate probable AD patients and 41 healthy controls. For comparison, MTL width replicating the technique of Jobst et al. (jMTL) as well as hippocampal and parahippocampal volumes, were also measured. Using logistic regression taking into account age, sex, and education, tMTL width classified mild AD from controls with a sensitivity of 86%, specificity of 95% and accuracy of 92%. Similar values were obtained for moderate or total AD group versus controls. By comparison, jMTL width was only useful in distinguishing moderate AD from controls, and volumetric measures were equally sensitive in classifying mild and moderate AD in our sample. This quick, reliable, and standardized measurement of tMTL can be helpful in differentiating even mild AD from controls with reasonable accuracy.

Accuracy of CT scan measurements of the medial temporal lobe in routine dementia diagnostics

BACKGROUND

Atrophy of the medial part of the temporal lobe is seen in Alzheimer's disease (AD). We studied the usefulness of CT scan measurements of the medial temporal lobe (MTL) in elderly with suspected dementia.

METHODS

MTL measurements were done with callipers by three raters, blinded to the diagnosis and to each other, on scans from 110 subjects with suspected dementia from a memory clinic in Oslo, Norway and 36 participants included in the OPTIMA study, Oxford, England.

RESULTS

The correlation between the MTL and the Mini-Mental State Examination (MMSE) was very low, and there was a marked overlap between Alzheimer and cognitively unimpaired subjects. The inter-rater reliability was lower on the Norwegian than on the OPTIMA scans (R = 0.48 vs R = 0.68), but this was partly explained by larger MTL readings (4.5 mm after adjustment for age, gender and MMSE sumscore) on the OPTIMA scans as the reliability was confounded by MTL width and was higher at larger MTLs. A wider scan width (3 mm vs 2 mm in the OPTIMA scans) can also contribute to differences in reliability.

CONCLUSIONS

The published threshold values regarding the CT scan MTL measurements for the diagnosis of AD may be invalid when applied by other radiology departments without a local standardisation and validation.

How do memory clinics compare with traditional old age psychiatry services?

METHODS

100 consecutive referrals to the Northern Memory Clinic (NMC) were compared with 100 referrals to a traditional Old Age Psychiatry (OAPsych) service in the same city in terms of demographic variables, cognitive function (assessed by the Mini-Mental State Examination), and diagnosis. The study also examined the ability of psychometric assessments (CAMCOG, MMSE, Trail-Making Tests A & B, Word Fluency) and CT scans included in the NMC assessment to differentiate between those with and without DSM-IV dementia.

RESULTS

NMC patients were significantly younger than OAPsych patients, had lower levels of cognitive impairment, and had a wider range of diagnoses. The NMC patients who were diagnosed as having dementia were found to be at least 2 years earlier in the course of the disease than those seen by the OAPsych team. The CAMCOG and MMSE were proved to be effective at distinguishing between patients diagnosed as dementing versus non-dementing with cut-offs of 82/83 and 23/24 respectively, confirming previous findings. The Memory subscale of the CAMCOG, though much shorter, was equally as effective using a cut-off of 20/21. Trail-Making Tests, Word Fluency (FAS), and measurement of the minimum width of the medial temporal lobe (MTL) on angled CT scans were poor indicators of dementia in this sample.

CONCLUSIONS

This study confirms that the memory clinic is targeting a distinct patient group compared to traditional old age psychiatry services, is identifying cases of dementia much earlier, and as such has potential to make valuable contributions to patient care.