Senjem, Matthew L.

ObjectiveThe aim of this study was to determine whether the frequency of TAR DNA‐binding protein 43 (TDP‐43) deposition in Alzheimer's disease (AD) differs across pathologically defined AD subtypes (hippocampal sparing [HpSp]; typical and limbic) and further examine the relationship between TDP‐43, pathological subtype, and clinical features in AD.MethodsWe identified all cases with pathologically confirmed AD (NIA‐Reagan intermediate‐high probability, Braak stage IV–VI) independent of cognitive status (n = 188). Neurofibrillary tangle counts were performed using thioflavin‐S microscopy in hippocampus and three neocortical regions, and all cases were subtyped: HpSp AD pathology (n = 19); typical AD pathology (n = 136); and limbic AD pathology (n = 33). TDP‐43 immunoreactivity was performed in multiple brain regions to assess for the presence of TDP‐43 and TDP‐43 stage. All cases were clinically subclassified at presentation as amnestic AD dementia versus atypical AD dementia. Statistical analysis was performed using linear and penalized logistic regression to assess associations with pathological subtype, and the effects of TDP‐43, accounting for possible interactions between pathological subtype and TDP‐43.ResultsTDP‐43 deposition was frequent in typical (59%) and limbic AD pathologies (67%), but not HpSp AD pathology (21%; p = 0.003). The observed associations of TDP‐43 with greater memory loss, naming and functional decline, and smaller hippocampal volumes, closest to death, did not differ across AD pathological subtype. Clinical presentation was associated with pathological subtype (p = 0.01), but not TDP‐43 (p = 0.69).InterpretationAlthough the frequency of TDP‐43 deposition in AD varies by pathological subtype, the observed effects of TDP‐43 on clinical/magnetic resonance imaging features are consistent across pathological subtypes. Clinical presentation in AD is driven by pathological subtype, not by TDP‐43. Ann Neurol 2015;78:Ann Neurol 2015;78:679–696

AbstractIntroductionAlzheimer's Disease Neuroimaging Initiative (ADNI) is now in its 10th year. The primary objective of the magnetic resonance imaging (MRI) core of ADNI has been to improve methods for clinical trials in Alzheimer's disease (AD) and related disorders.MethodsWe review the contributions of the MRI core from present and past cycles of ADNI (ADNI‐1, ‐Grand Opportunity and ‐2). We also review plans for the future‐ADNI‐3.ResultsContributions of the MRI core include creating standardized acquisition protocols and quality control methods; examining the effect of technical features of image acquisition and analysis on outcome metrics; deriving sample size estimates for future trials based on those outcomes; and piloting the potential utility of MR perfusion, diffusion, and functional connectivity measures in multicenter clinical trials.DiscussionOver the past decade the MRI core of ADNI has fulfilled its mandate of improving methods for clinical trials in AD and will continue to do so in the future.

Background and purpose A subset of patients with Alzheimer's disease ( AD ) present with early and prominent language impairment (aphasic AD ). Our previous study demonstrated an association between global β‐amyloid burden measured on [ 11 C] Pittsburgh compound B (PiB) positron emission tomography and general cognitive impairment, but not with aphasia, in such subjects. As a follow‐up, whether there is any association between regional β‐amyloid burden, atrophy on magnetic resonance imaging ( MRI ) and global cognitive impairment, aphasia or other cognitive and functional impairment in aphasic AD is assessed. Methods Forty‐four aphasic AD subjects who underwent PiB scanning and volumetric MRI and were determined to be positive for β‐amyloid deposition were analyzed. All had completed detailed neurological, neuropsychological and language batteries. Spearman's rank‐order correlation was utilized to assess for associations. Results Greater visuospatial impairment was associated with increased β‐amyloid burden in the primary visual cortex ( P = 0.001). Although there were many trends for associations between neurocognitive and language deficits and regional β‐amyloid burden, there were no strong associations that survived correction for multiple comparisons. However, neurocognitive and language impairment in these subjects strongly correlated with the degree of left lateral temporal and inferior parietal atrophy ( P < 0.004). Conclusions The findings from this study suggest a close relation between the severity of regional atrophy and cognitive and language impairment, but argue against a strong association between regional β‐amyloid burden and such deficits in aphasic AD subjects. Hence, other pathological factors may be driving the previously identified association between global β‐amyloid deposition and general cognitive impairment in aphasic AD .

Background and purposeThe aim of our study was to determine the utility of longitudinal magnetic resonance imaging (MRI) measurements as potential biomarkers in the main genetic variants of frontotemporal dementia (FTD), including microtubule‐associated protein tau (MAPT) and progranulin (GRN) mutations and C9ORF72 repeat expansions, as well as sporadic FTD.MethodsIn this longitudinal study, 58 subjects were identified who had at least two MRI and MAPT mutations (n = 21), GRN mutations (n = 11), C9ORF72 repeat expansions (n = 11) or sporadic FTD (n = 15). A total of 198 serial MRI measurements were analyzed. Rates of whole brain atrophy were calculated using the boundary shift integral. Regional rates of atrophy were calculated using tensor‐based morphometry. Sample size estimates were calculated.ResultsProgressive brain atrophy was observed in all groups, with fastest rates of whole brain atrophy in GRN, followed by sporadic FTD, C9ORF72 and MAPT. All variants showed greatest rates in the frontal and temporal lobes, with parietal lobes also strikingly affected in GRN. Regional rates of atrophy across all lobes were greater in GRN compared to the other groups. C9ORF72 showed greater rates of atrophy in the left cerebellum and right occipital lobe than MAPT, and sporadic FTD showed greater rates in the anterior cingulate than C9ORF72 and MAPT. Sample size estimates were lowest using temporal lobe rates in GRN, ventricular rates in MAPT and C9ORF72, and whole brain rates in sporadic FTD.ConclusionThese data support the utility of using rates of atrophy as outcome measures in future drug trials in FTD and show that different imaging biomarkers may offer advantages in the different variants of FTD.