Whitwell, Jennifer L.

AbstractIntroductionLittle is known about the role of age on neurodegeneration and protein deposition in atypical variants of Alzheimer's disease (AD).MethodsRegional tau and β‐amyloid positron emission tomography standard uptake value ratios and gray matter volumes were calculated in a cohort of 42 participants with atypical AD. The relationship between regional metrics and age was modeled using a Bayesian hierarchical linear model.ResultsAge was strongly associated with tau uptake across all cortical regions, particularly parietal, with greater uptake in younger participants. Younger age was associated with smaller parietal and lateral temporal volumes. Regional β‐amyloid differed little by age. Age showed a stronger association with tau than volume and β‐amyloid in all cortical regions. Age was not associated with cognitive performance.DiscussionAge is an important determinant of severity of cortical tau uptake in atypical AD, with young participants more likely to show widespread and severe cortical tau uptake.

This study examined the rate of producing alternating motion rates, sequential motion rates (SMRs), and repeated words in 27 individuals with the semantic variant of Primary Progressive Aphasia (svPPA). Only the rate of producing SMRs was significantly elevated in svPPA compared to controls. This may be associated with concomitant neuropsychiatric symptoms in svPPA, as correlation analysis showed a relationship between increased SMR rate and the Neuropsychiatric Inventory Questionnaire, which documented anxiety and disinhibition. Future studies will assess these findings in a larger cohort and work to better understand if this phenomenon is a manifestation of behavioral and/or motor changes.

AbstractAlzheimer's disease (AD) can present with atypical clinical forms where the prominent domain of deficit is not memory, that is, atypical AD. Atypical AD patients show cortical atrophy on MRI, hypometabolism on [18F]fluorodeoxyglucose (FDG) PET, tau uptake on [18F]AV‐1451 PET, and white matter tract degeneration on diffusion tensor imaging (DTI). How these disease processes relate to each other locally and distantly remains unclear. We aimed to examine multimodal neuroimaging relationships in individuals with atypical AD, using univariate and multivariate techniques at region‐ and voxel‐level. Forty atypical AD patients underwent MRI, FDG‐PET, tau‐PET, beta‐amyloid PET, and DTI. Patients were all beta‐amyloid positive. Partial Pearson's correlations were performed between tau and FDG standardized uptake value ratios, gray matter MRI‐volumes and white matter tract fractional anisotropy. Sparse canonical correlation analysis was applied to identify multivariate relationships between the same quantities. Voxel‐level associations across modalities were also assessed. Tau showed strong local negative correlations with FDG metabolism in the occipital and frontal lobes. Tau in frontal and parietal regions was negatively associated with temporoparietal gray matter MRI‐volume. Fractional anisotropy in a set of posterior white matter tracts, including the splenium of the corpus callosum, cingulum, and posterior thalamic radiation, was negatively correlated with parietal and occipital tau, atrophy and, predominantly, with hypometabolism. These results support the view that tau is the driving force behind neurodegeneration in atypical AD, and that a breakdown in structural connectivity is related to cortical neurodegeneration, particularly hypometabolism.

Purpose This case series details the clinical progression of patients with primary progressive apraxia of speech (PPAOS) to illustrate, using several methods and supplemental material examples, the changes that occur in speech and language functioning in this patient population. Method Four patients who presented with PPAOS were followed between 5 and 6 years. Two patients had predominant articulatory abnormalities (termed phonetic PPAOS ), 1 had predominant prosodic abnormalities (prosodic PPAOS), and 1 had relatively equal articulatory and prosodic abnormalities (mixed PPAOS). Detailed speech (including acoustics), language, neurologic, and neuropsychological data were collected. Results At initial exam, the patients ranged from 60 to 77 years old, with presenting disease duration of 1.5–10 years. Although all patients presented with an isolated apraxia of speech, all developed varying degrees of aphasia and dysarthria. Patients with phonetic PPAOS developed relatively more severe aphasia than the other 2 patients. All patients eventually had severe functional communication limitations and required alternative or augmentative means of communication, although at varying times postonset of their initial speech problem. Two patients developed dysphagia, 3 showed mild–moderate Parkinsonism, and 2 developed depression. For all patients, simple temporal acoustic measurements documented slowed speech rate over time. Conclusions This case series demonstrates that patients who initially present with PPAOS may develop aphasia and dysarthria, cognitive and behavioral changes, and other neurologic signs. Whether these changes can be predicted by the perceptual characteristics of the apraxia of speech is yet to be determined. The detailed longitudinal profiles provide valuable clinical insight into the progression of disease in people with PPAOS. Supplemental Material https://doi.org/10.23641/asha.7051616

AbstractBackgroundElevated uptake of the [18F]AV‐1451 tau‐PET ligand has been observed cross‐sectionally in subjects with progressive supranuclear palsy (PSP). However, it is unknown how the ligand performs longitudinally in PSP. We aimed to determine how regional measures of change on [18F]AV‐1451 PET perform as longitudinal biomarkers of PSP compared with the more established biomarker of rate of midbrain atrophy.MethodsSixteen subjects with PSP underwent 2 serial [18F]AV‐1451 tau‐PET scans and 3‐Tesla MRI over 12 months and were age‐ and sex‐matched to 39 healthy controls with longitudinal [18F]AV‐1451 PET. Median [18F]AV‐1451 uptake was calculated for each scan for regions of interest across the brain and divided by uptake in cerebellar crus to create standard uptake value ratios. Midbrain volume on MRI was also calculated for each scan. Sample sizes required to power placebo‐controlled treatment trials were calculated.ResultsRate of midbrain atrophy was significantly increased in PSP compared with controls. [18F]AV‐1451 regional change measures were significantly increased in PSP compared with controls in the pallidum, precentral cortex, dentate nucleus of the cerebellum, and midbrain. Change over time in the PSP Rating Scale correlated with change in midbrain volume but did not correlate with change in the [18F]AV‐1451 measures. Smallest sample‐size estimates were obtained with rate of midbrain atrophy, followed by the PSP Rating Scale, with both outperforming [18F]AV‐1451 measures.Conclusions[18F]AV‐1451 tau‐PET measures increase over time in subjects with PSP, but longitudinal [18F]AV‐1451 measures may not perform as well as rate of midbrain atrophy as biomarkers for PSP clinical trials. © 2018 International Parkinson and Movement Disorder Society

Background: Neuropsychological assessment can add essential information to the characterization of individuals presenting with the logopenic variant of primary progressive aphasia (lvPPA). Objective: This study examined the neuropsychological characteristics of lvPPA patients. We also examined differences in regional and whole brain atrophy based on neuropsychological profiles. Methods: We conducted a hierarchical cluster analysis on memory, executive functioning, and visuospatial neuropsychological test data for 56 individuals with lvPPA. We then compared resultant clusters to left middle temporal, inferior parietal, and superior parietal regions-of-interest using multivariate analysis of covariance. We also performed voxel-level analyses. Results: We identified three clusters characterized as lvPPA with no neurocognitive impairment ( n = 5), lvPPA with mild neurocognitive deficits ( n = 23), and lvPPA with marked cognitive deficits ( n = 28). WAB-AQ was associated with left middle temporal volume. Superior parietal volumes were smaller for the lvPPA group with marked cognitive symptoms compared to the less severe groups. Voxel-level analyses showed greater atrophy in temporal, parietal, lateral occipital, and frontal regions, left worse than right. Age, disease duration, gender, WAB-AQ, and PiB-PET did not account for differences between groups. Conclusions: LvPPA patients without cognitive deficits in other domains were relatively uncommon while 50% of our sample exhibited pronounced neurocognitive deficits outside the language domain. Pronounced cognitive deficits in lvPPA are associated with widespread atrophy, left worse than right. Our study underscores the importance of examining neuropsychological function in addition to language in patients with lvPPA.