Cerebral blood flow changes during aging process and in cognitive disorders: A review

We aimed to summarize the available evidence on cerebral blood flow (CBF) changes in normal aging and common cognitive disorders. We searched PubMed for studies on CBF changes in normal aging and cognitive disorders up to 1 January 2019. We summarized the milestones in the history of CBF assessment and reviewed the current evidence on the association between CBF and cognitive changes in normal aging, vascular cognitive impairment (VCI) and Alzheimer’s disease (AD). There is promising evidence regarding the utility of CBF studies in cognition research. Age-related CBF changes could be related to a progressive neuronal loss or diminished activity and synaptic density of neurons in the brain. While a similar cause or outcome theory applies to VCI and AD, it is possible that CBF reduction might precede cognitive decline. Despite the diversity of CBF research findings, its measurement could help early detection of cognitive disorders and also understanding their underlying etiology.

Radiological biomarkers for diagnosis in PSP: Where are we and where do we need to be?

PSP is a pathologically defined neurodegenerative tauopathy with a variety of clinical presentations including typical Richardson's syndrome and other variant PSP syndromes. A large body of neuroimaging research has been conducted over the past two decades, with many studies proposing different structural MRI and molecular PET/SPECT biomarkers for PSP. These include measures of brainstem, cortical and striatal atrophy, diffusion weighted and diffusion tensor imaging abnormalities, [18F] fluorodeoxyglucose PET hypometabolism, reductions in striatal dopamine imaging and, most recently, PET imaging with ligands that bind to tau. Our aim was to critically evaluate the degree to which structural and molecular neuroimaging metrics fulfill criteria for diagnostic biomarkers of PSP. We queried the PubMed, Cochrane, Medline, and PSYCInfo databases for original research articles published in English over the past 20 years using postmortem diagnosis or the NINDS-SPSP criteria as the diagnostic standard from 1996 to 2016. We define a five-level theoretical construct for the utility of neuroimaging biomarkers in PSP, with level 1 representing group-level findings, level 2 representing biomarkers with demonstrable individual-level diagnostic utility, level 3 representing biomarkers for early disease, level 4 representing surrogate biomarkers of PSP pathology, and level 5 representing definitive PSP biomarkers of PSP pathology. We discuss the degree to which each of the currently available biomarkers fit into this theoretical construct, consider the role of biomarkers in the diagnosis of Richardson's syndrome, variant PSP syndromes and autopsy confirmed PSP, and emphasize current shortfalls in the field. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Pure akinesia with low myocardial metaiodobenzylguanidine uptake

The objective of this study was to delineate the clinical features of patients with pure akinesia and a low heart versus mediastinum ratio below 2.0 in the delayed images of myocardial metaiodobenzylguanidine scintigraphy, a marker for the clinical diagnosis of Lewy body diseases. A total of 13 patients was enrolled. The clinical features of the patients were uniformly elderly (mean age, 73.7 years), a male gender preponderance (10 men and 3 women), relatively mild motor disability (mean Hoehn Yahr grade 2.4) without laterality, festinating gait (77%) and loss of postural reflex (69%), which were the most common; also observed were fair levodopa responses (70%), cognitive dysfunction in some (23%), common autonomic dysfunction (urinary urgency and frequency, 85%; constipation, 77%; and postural hypotension, 38%) and common occipital hypoperfusion (62%). These features may facilitate the clinical differential diagnosis of these patients from patients with pure akinesia due to progressive supranuclear palsy.

PSP as distinguished from CBD, MSA-P and PD by clinical and imaging differences at an early stage

OBJECTIVE

Because it is often difficult to precisely diagnose and distinguish progressive supranuclear palsy (PSP) from corticobasal degeneration (CBD), multiple system atrophy-parkinsonism (MSA-P) and Parkinson's disease (PD) at the onset of the disease, we compared the patients and clarified the features of these diseases.

METHODS

We compared 77 PSP, 26 CBD, 26 MSA-P and 166 PD patients from clinical and imaging points of view including cerebral blood flow (CBF) in the frontal eye field.

RESULTS

The clinical characteristics of PSP were supranuclear gaze disturbance, optokinetic nystagmus (OKN) impairment and falls at the first visit. On head MRI, midbrain tegmentum atrophy was much more frequently detected in PSP than in all of the other groups. Heart-to-mediastinum average count ratio (H/M) in iodine-123 meta-iodobenzyl guanidine ((123)I-MIBG) myocardial scintigraphy was not decreased in PSP, CBD, MSA-P and PD-Yahr 1 (-1), but patients of PD-2, 3, 4 and 5 showed a significant decrease compared with the PSP group. The CBF in the left frontal eye field of PD-3 group and that in right frontal eye field of PD-3 and PD-4 groups were lower than that of PSP group, although other groups showed a tendency without a significant decrease compared with PSP group.

CONCLUSION

PSP is distinguishable from CBD, MSA-P and PD even at the early stage with extra-ocular movement (EOM) disturbance, falls, atrophy of the midbrain tegmentum, and H/M in (123)I-MIBG myocardial scintigraphy, and the reduction of CBF in area 8 could serve as a supplemental diagnostic method for distinguishing PSP from PD-3 or PD-4.