What can imaging tell us about cognitive impairment and dementia?

Abstract

Dementia is a contemporary global health issue with far reaching consequences, not only for affected individuals and their families, but for national and global socioeconomic conditions. The hallmark feature of dementia is that of irreversible cognitive decline, usually affecting memory, and impaired activities of daily living. Advances in healthcare worldwide have facilitated longer life spans, increasing the risks of developing cognitive decline and dementia in late life. Dementia remains a clinical diagnosis. The role of structural and molecular neuroimaging in patients with dementia is primarily supportive role rather than diagnostic, American and European guidelines recommending imaging to exclude treatable causes of dementia, such as tumor, hydrocephalus or intracranial haemorrhage, but also to distinguish between different dementia subtypes, the commonest of which is Alzheimer's disease. However, this depends on the availability of these imaging techniques at individual centres. Advanced magnetic resonance imaging (MRI) techniques, such as functional connectivity MRI, diffusion tensor imaging and magnetic resonance spectroscopy, and molecular imaging techniques, such as 18F fluoro-deoxy glucose positron emission tomography (PET), amyloid PET, tau PET, are currently within the realm of dementia research but are available for clinical use. Increasingly the research focus is on earlier identification of at risk preclinical individuals, for example due to family history. Intervention at the preclinical stages before irreversible brain damage occurs is currently the best hope of reducing the impact of dementia.

An Overview of Human Immunodeficiency Virus Type 1-Associated Common Neurological Complications: Does Aging Pose a Challenge?

“…Although earlier studies in primate models suggest the possibility of separating simian immunodeficiency viruses (SIV)/AIDS from SIV encephalitis by identifying novel metabolites using MRS scanning, its clinical application in human patients has not been tested [17]. However, recent advances in in vivo molecular and structural brain imaging techniques for patients with dementia, or dementia-associated diseases like Alzheimer’s disease (AD) or Parkinson’s disease (PD), offer a great opportunity to design precise therapeutic strategies to combat the disease from its early onset [18]. …”

Imaging Morphologic Substrates and Molecular Changes for Differential Diagnosis of Vascular Dementia

“…As these studies provide insight in early changes of the diseases, selective PETstudies might be useful to detect preclinical stages in which therapeutic efforts might be promising. Multimodal imaging including advanced techniques for morphological and molecular imaging are important for research in dementias, but are also more and more introduced into clinical application [43][44][45].…”

Lesion load assessment among multiple sclerosis patient using DIR, FLAIR, and T2WI sequences

“…Although conventional MRI sequences are not successful in cortical lesions demonstration, and despite the advances in new MR techniques such as magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI), still conventional MRI protocols playing an important role in early diagnosis of MS or CIS (suggestive of MS) [4][5][6].…”

“…The disease affects the calloso-septal interface, periventricular white matter, cerebellum, and brain stem [3,4]. Several studies revealed that most MS lesion load histologically are on the cerebral cortex specifically the gray matter and white mater interface [5], which commonly associated with cognitive disability which can be revealed by magnetic resonance imaging (MRI) [6]. It was established that lesion load measurement on brain could predict neurological disorders occurred during several years.…”