Magnetic resonance imaging and computed tomography in Alzheimer's disease

Exploring the Value of MRI Measurement of Hippocampal Volume for Predicting the Occurrence and Progression of Alzheimer's Disease Based on Artificial Intelligence Deep Learning Technology and Evidence-Based Medicine Meta-Analysis

BACKGROUND

Alzheimer's disease (AD), a major dementia cause, lacks effective treatment. MRI-based hippocampal volume measurement using artificial intelligence offers new insights into early diagnosis and intervention in AD progression.

OBJECTIVE

This study, involving 483 AD patients, 756 patients with mild cognitive impairment (MCI), and 968 normal controls (NC), investigated the predictive capability of MRI-based hippocampus volume measurements for AD risk using artificial intelligence and evidence-based medicine.

METHODS

Utilizing data from ADNI and OASIS-brains databases, three convolutional neural networks (InceptionResNetv2, Densenet169, and SEResNet50) were employed for automated AD classification based on structural MRI imaging. A multitask deep learning model and a densely connected 3D convolutional network were utilized. Additionally, a systematic meta-analysis explored the value of MRI-based hippocampal volume measurement in predicting AD occurrence and progression, drawing on 23 eligible articles from PubMed and Embase databases.

RESULTS

InceptionResNetv2 outperformed other networks, achieving 99.75% accuracy and 100% AUC for AD-NC classification and 99.16% accuracy and 100% AUC for MCI-NC classification. Notably, at a 512×512 size, InceptionResNetv2 demonstrated a classification accuracy of 94.29% and an AUC of 98% for AD-NC and 97.31% accuracy and 98% AUC for MCI-NC.

CONCLUSIONS

The study concludes that MRI-based hippocampal volume changes effectively predict AD onset and progression, facilitating early intervention and prevention.

A task force for diagnosis and treatment of people with Alzheimer's disease in Latin America

Alzheimer's disease (AD) represents a substantial burden to patients, their caregivers, health systems, and society in Latin America and the Caribbean (LAC). This impact is exacerbated by limited access to diagnosis, specialized care, and therapies for AD within and among nations. The region has varied geographic, ethnic, cultural, and economic conditions, which create unique challenges to AD diagnosis and management. To address these issues, the Americas Health Foundation convened a panel of eight neurologists, geriatricians, and psychiatrists from Argentina, Brazil, Colombia, Ecuador, Guatemala, Mexico, and Peru who are experts in AD for a three-day virtual meeting to discuss best practices for AD diagnosis and treatment in LAC and create a manuscript offering recommendations to address identified barriers. In LAC, several barriers hamper diagnosing and treating people with dementia. These barriers include access to healthcare, fragmented healthcare systems, limited research funding, unstandardized diagnosis and treatment, genetic heterogeneity, and varying social determinants of health. Additional training for physicians and other healthcare workers at the primary care level, region-specific or adequately adapted cognitive tests, increased public healthcare insurance coverage of testing and treatment, and dedicated search strategies to detect populations with gene variants associated with AD are among the recommendations to improve the landscape of AD.

MRI findings suggestive of Alzheimer's disease in patients with primary open angle glaucoma - a single sequence analysis using rapid 3D T1 spoiled gradient echo

OBJECTIVE

Primary open-angle glaucoma (POAG) is a degenerative optic neuropathy disease which has somewhat similar pathophysiology to Alzheimer's disease (AD). This study aims to determine the presence of medial temporal atrophy and parietal lobe atrophy in patients with POAG compared to normal controls using medial temporal atrophy (MTA) scoring and posterior cortical atrophy (PCA) scoring system on T1 magnetization-prepared rapid gradient-echo.

METHODS

50 POAG patients and 50 normal subjects were recruited and an MRI brain with T1-magnetization-prepared rapid gradient-echo was performed. Medial temporal lobe and parietal lobe atrophy were by MTA and PCA/Koedam scoring. The score of the PCA and MTA were compared between the POAG group and the controls.

RESULTS

There was a significant statistical difference between PCA score in POAG and the healthy control group (p-value = 0.026). There is no statistical difference between MTA score in POAG compared to the healthy control group (p-value = 0.58).

CONCLUSION

This study suggests a correlation between POAG and PCA score. Potential application of this scoring method in clinical diagnosis and monitoring of POAG patients.

ADVANCES IN KNOWLEDGE

The scoring method used in AD may also be applied in the diagnosis and monitoring of POAGMRI brain, specifically rapid volumetric T1 spoiled gradient echo sequence, may be applied in POAG assessment.

Quantitative MR imaging in Alzheimer disease

Alzheimer disease (AD) is the most common type of dementia. It currently affects approximately 4 million people in the United States. AD is a progressive neurodegenerative disorder characterized by the gradual deposition of neuritic plaques and neurofibrillary tangles in the brain, which is thought to occur decades before the onset of clinical symptoms. Identification of people at risk before the clinical appearance of dementia has become a priority due to the potential benefits of therapeutic intervention. Although atrophy of medial temporal lobe structures has been shown to correlate with progression of AD, a growing number of recent reports have indicated that such atrophy may not be specific to AD. To improve diagnostic specificity, new quantitative magnetic resonance (MR) imaging methods are being developed that exploit known pathogenic mechanisms exclusive to AD. This article reviews the MR techniques that are currently available for the diagnostic assessment of AD.

In vivo study of acetylcholine esterase in basal forebrain, amygdala, and cortex in mild to moderate Alzheimer disease

It is currently unclear whether impairment of the cholinergic system is present in Alzheimer disease (AD) already at an early stage and to what extent it depends on degeneration of the nucleus basalis of Meynert (nbM). We examined acetylcholine esterase activity in vivo in the nbM, the amygdala, and cerebral neocortex. Measurements were performed in normal controls and in patients with mild to moderate AD with positron emission tomography (PET) and C-11-labeled N-methyl-4-piperidyl-acetate (MP4A) which is a specific substrate of AChE. AChE activity was reduced significantly in amygdala and cerebral cortex. In contrast, AChE activity and glucose metabolism appeared preserved or even increased in the nbM. The results support the concept that neocortical and amygdaloid functional changes of the cholinergic system are an early and leading event in AD, rather than the consequence of neurodegeneration of basal nuclei.

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.

Volumetric study of lobar atrophy in Pick complex and Alzheimer's disease

BACKGROUND

Lobar atrophy is an important neuroimaging feature of Pick complex (PiC). However, differences in patterns of focal brain atrophy between PiC and Alzheimer's disease (AD), and among PiC subgroups, have not been studied quantitatively.

OBJECTIVE

To compare volumetric measures among primary progressive aphasia (PPA), frontotemporal dementia (FTD) and AD; to assess association between brain atrophy and cognition.

PATIENTS

Seventeen patients with PPA, 11 with FTD and 24 with probable AD were studied.

METHODS

We measured total and regional volume quantitatively using MRI and computerized volumetry. Contributing factors were controlled statistically or by adopting brain volume ratios. We investigated the classifying power of volumetry and correlated regional brain volume with cognitive and language test scores.

RESULTS

The ratio for fronto-temporo-central region was smaller on the left in PPA and on the right in FTD. AD and some PPA patients had smaller parietal lobes. The frontal ratios correctly classified 93% of PPA and FTD patients, but only 50% of the entire PiC and AD patients. Language-dependent examinations correlated with the left fronto-temporal volume.

CONCLUSIONS

Brain atrophy differs in PPA, FTD and AD, but there is some morphological overlap between PiC and AD in parietal volumes. Focal brain atrophy is most consistently associated with language impairments.

Age-related brain changes associated with motor function in healthy older people

OBJECTIVE

To identify the MRI imaging findings associated with motor changes in healthy older people.

DESIGN

A cross-sectional study.

SETTING

A study of neurologic function in very healthy older people, the Oregon Brain Aging Study.

PARTICIPANTS

Clinical and MRI data were examined in 50 very healthy older subjects (mean age = 85.1, SD = 7.2 years).

MEASUREMENTS

Clinical measures (finger tapping, hand opening and closing, steps and time to walk 30 feet and timed standing on one foot) were dependent variables in multiple regression analyses using age and the following MRI measures as independent variables: total brain volume (TBV)/intracranial volume; ventricular volume/TBV; periventricular high signal/TBV; deep high signal/TBV.

RESULTS

The number of steps and the time to walk 30 feet were each associated with periventricular high signal (steps: r = .58, P < .001; time: r = .60, P < .001) and ventricular volume (steps: r = .54, P < .001; time: r = .58, P < .001). These associations remained significant after adjusting for age. None of the other clinical variables was associated with the MRI volumes.

CONCLUSIONS

Gait measures were associated significantly with periventricular high signal and ventricular volume. These CNS changes contribute to the cause of these important markers of aging.

Brain functions and psychiatric disorders. A clinical view

Psychiatric disorders are viewed as brain disorders affecting five circuits of the brain: the brainstem, the hypothalamus, the motor striatum, the limbic system (ventral striatum), and the neocortex. This five-circuit model combines neuroscientific, psychopharmacologic, evolutionary, introspective, and behavioral data. The article presents a broad speculative overview of some brain functions and dysfunctions relevant for clinicians.

Evolution in the conceptualization of dementia and Alzheimer's disease: Greco-Roman period to the 1960s

Most histories of senile dementia commence with Alois Alzheimer's description in 1906 of the first case of Alzheimer's disease, yet the history of senile dementia before 1906 is quite rich, dating back to the ancient Greek and Roman philosophers and physicians. Over the 2500 years since ancient times, the concept of senile dementia has evolved from a rather vague notion that mental decline occurred inevitably in old age, to become defined today by a distinct set of clinical and pathological features with the potential for treatment and prevention within grasp. Throughout history, many elderly individuals with unpredictable behavior were sequestered in institutions, and the line between mental disorders and senile dementia was hazy at best. The identification of Alzheimer's disease at the onset of the 20th century was a turning point for the understanding of senile dementia, and the concepts and histological findings presented by the early researchers of Alzheimer's disease remain relevant still today. Indeed, these early findings are proving to be a continuing source of insight, as many of the issues debated at the turn of the century remain unresolved still today. This paper thus traces the history of the evolution of our current conceptualization of Alzheimer's disease from the amorphous Greco-Roman concept of age-associated dementia.