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  • 1
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2006
    In:  Nature Materials Vol. 5, No. 3 ( 2006-03-01), p. 185-188
    In: Nature Materials, Springer Science and Business Media LLC, Vol. 5, No. 3 ( 2006-03-01), p. 185-188
    Type of Medium: Online Resource
    ISSN: 1476-1122 , 1476-4660
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2006
    detail.hit.zdb_id: 2088679-2
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  • 2
    In: European Journal of Neuroscience, Wiley, Vol. 54, No. 9 ( 2021-11), p. 7260-7273
    Abstract: The ability to flexibly manipulate memory representations is embedded in visual working memory (VWM) and can be tested using paradigms with retrospective cues. Although valid retrospective cues often facilitate memory recall, invalid ones may or may not result in performance costs. We investigated individual differences in utilising retrospective cues and evaluated how these individual differences are associated with brain oscillatory activity at rest. At the behavioural level, we operationalised flexibility as the ability to make effective use of retrospective cues or disregard them if required. At the neural level, we tested whether individual differences in such flexibility were associated with properties of resting‐state alpha oscillatory activity (8–12 Hz). To capture distinct aspects of these brain oscillations, we evaluated their power spectral density and temporal dynamics using long‐range temporal correlations (LRTCs). In addition, we performed multivariate patterns analysis (MVPA) to classify individuals' level of behavioural flexibility based on these neural measures. We observed that alpha power alone (magnitude) at rest was not associated with flexibility. However, we found that the participants' ability to manipulate VWM representations was correlated with alpha LRTC and could be decoded using MVPA on patterns of alpha power. Our findings suggest that alpha LRTC and multivariate patterns of alpha power at rest may underlie some of the individual differences in using retrospective cues in working memory tasks.
    Type of Medium: Online Resource
    ISSN: 0953-816X , 1460-9568
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2005178-5
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    AIP Publishing ; 2004
    In:  Applied Physics Letters Vol. 85, No. 4 ( 2004-07-26), p. 528-530
    In: Applied Physics Letters, AIP Publishing, Vol. 85, No. 4 ( 2004-07-26), p. 528-530
    Abstract: We report on the formation of surface structures by photopolymerization of C60 and C70 in isotropic solutions. The structures show the same periodicity of the interference patterns used for photopolymerization and behave as diffraction gratings. Mass spectrometry confirmed that the deposited material contains polymerized fullerenes, while the structure of the deposit was investigated by atomic force microscopy. We have also shown that these periodic structures are useful for inducing mesophase orientation.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    RVK:
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2004
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 4
    In: Alzheimer's & Dementia, Wiley, Vol. 16, No. S6 ( 2020-12)
    Abstract: The link between late‐life depression and Alzheimer’s disease (AD) has long been investigated, however it is still unclear whether depression acts as a risk factor, a prodromal feature or a comorbid condition in AD. Clarifying the nature of this link has important implications in the early intervention and diagnosis of AD. The relatively recent introduction of in‐vivo brain biomarkers for AD pathology offers the chance to explore the relationship between depression and pathologically‐confirmed neurodegeneration. Here, we examined the association among objective cognitive functioning, self‐reported cognitive failures and AD pathology in patients with late‐life depression. Method Sixty‐three older adults with no formal diagnosis of cognitive impairment underwent a comprehensive cognitive assessment and Amyloid‐PET Imaging at the Imperial Memory Unit. Participants were classified into two groups, according to the presence (n=33, mean age=71.82 ±4.98) or absence (n=30, mean age=71.30 ±5.80) of late‐life depression. Late‐life depression was confirmed through validated questionnaires (GDS ≥ 6 and/or HDRS ≥ 12) and medical history review. Amyloid‐PET images were qualitatively read as amyloid positive or amyloid negative by two experienced nuclear medicine radiologists (NMRs). Equivocal scans (6%) were read by a third independent NMR. Cognitive data in the two groups were compared using non‐parametric tests. Results Amyloid status did not differ significantly between the two groups (p=.367), with 3 (9%) depressed and 5 (17%) non‐depressed participants reported as amyloid‐positive. Despite higher levels of self‐reported cognitive failures (p 〈 .001), the depressed group did not differ from the non‐depressed group in a global measure of cognition (MMSE depressed: 28.09±1.69; non‐depressed: 28.93±4.66) and showed worse performance in 4 (Word List short‐delay recall, Digit Span backward and forward, Coding) of the 17 cognitive measures administered. Follow up data, currently being collected at our Unit, will add information about the long‐term trajectory of cognition in late life depression. Conclusions In our sample, depressive symptoms were associated with a limited number of cognitive measures but not with AD pathology. This suggests that depression seems to have a limited role in the early diagnosis of AD. Future studies should examine the role of specific features of depression and of other widespread neuropsychiatric symptoms (e.g., anxiety) in AD.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2201940-6
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  • 5
    In: Alzheimer's & Dementia, Wiley, Vol. 16, No. S6 ( 2020-12)
    Abstract: The early cognitive profile of Alzheimer’s Disease (AD) is typically characterised by predominant impairment in episodic memory, reflecting medial temporal lobe dysfunction. However, little is known about the cognitive profile associated with AD pathology in those patients who meet Appropriate Use Criteria (AUC, Johnson et al., 2013) for Amyloid PET Imaging (API). In this group, AD pathology is frequently associated with an atypical clinical course or presentation. Here, we systematically evaluate the cognitive profiles of AUC‐meeting patients in a real‐world clinical setting, combining the information provided by the neuropsychological assessment with the results of Amyloid PET Imaging. Method From a larger sample of 396 patients who underwent Amyloid PET at the Imperial Memory Centre between December 2013 and June 2019, we included those individuals who also had at least one formal neuropsychological assessment (minimum of 4 tests) within 18 months of API (n=124). Both these were solely conducted for clinical purposes, and API was requested after multidisciplinary team discussion. Cognitive measures in amyloid positive (Aβ+) and negative (Aβ‐) patients were compared using non‐parametric tests. Results Neuropsychological assessment preceded Amyloid PET Imaging in most cases, for both amyloid‐positive (n=51, mean age 67.24±9.32 years, 58.8% female) and amyloid‐negative (n=73, mean age 67.9±9.64 years, 41.1% female) groups. Cognitive performance in the amyloid‐positive group was significantly worse in 6 of the 14 cognitive measures taken into account: visuo‐spatial functioning, executive functioning, working memory, verbal learning, verbal delayed recall, and confrontation naming (Figure 1). Verbal learning, verbal delayed recall and confrontation naming were the most frequently impaired measures in the amyloid‐positive group, with around 50% of patients performing below 2 standard deviations. Notably, self‐reported symptoms of depression were significantly higher in the amyloid‐negative (7.3±4.38) than in the amyloid‐positive group (4.68±3.7) (p=.002) ( Figure 2 ) . Conclusions In a sample of patients attending a tertiary Behavioural Neurology clinic, neuropsychological evaluation revealed worse performance in positive API across a range of domains, particularly verbal memory and confrontation naming, with higher rates of symptoms of depression being reported more frequently in the amyloid negative group.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2201940-6
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  • 6
    In: Brain Communications, Oxford University Press (OUP), Vol. 3, No. 2 ( 2021-04-05)
    Abstract: Episodic memory impairment and brain amyloid-beta are two of the main hallmarks of Alzheimer’s Disease. In the clinical setting, these are often evaluated through neuropsychological testing and amyloid PET imaging, respectively. The use of amyloid PET in clinical practice is only indicated in patients with substantial diagnostic uncertainty due to atypical clinical presentation, multiple comorbidities and/or early age of onset. The relationship between amyloid-beta and cognition has been previously investigated, but no study has examined how neuropsychological features relate to the presence of amyloid pathology in the clinical population that meets the appropriate use criteria for amyloid PET imaging. In this study, we evaluated a clinical cohort of patients (n = 107) who presented at the Imperial Memory Clinic and were referred for clinical amyloid PET and neuropsychological assessment as part of their diagnostic workup. We compared the cognitive performance of amyloid-positive patients (Aβ-pos, n = 47) with that of stable amyloid-negative (stableAβ-neg, n = 26) and progressive amyloid-negative (progAβ-neg, n = 34) patients. The amyloid-positive group performed significantly worse than both amyloid-negative groups in the visuospatial and working memory domains. Episodic memory performance, however, effectively differentiated the amyloid-positive group from the stable but not the progressive amyloid-negative group. On affective questionnaires, the stable amyloid-negative group reported significantly higher levels of depression than the amyloid-positive group. In our clinical cohort, visuospatial dysfunction and working memory impairment were better indicators of amyloid positivity than episodic memory dysfunction. These findings highlight the limited value of isolated cognitive scores in patients with atypical clinical presentation, comorbidities and/or early age of onset.
    Type of Medium: Online Resource
    ISSN: 2632-1297
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 3020013-1
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  • 7
    Online Resource
    Online Resource
    American Chemical Society (ACS) ; 2008
    In:  Chemistry of Materials Vol. 20, No. 21 ( 2008-11-11), p. 6589-6591
    In: Chemistry of Materials, American Chemical Society (ACS), Vol. 20, No. 21 ( 2008-11-11), p. 6589-6591
    Type of Medium: Online Resource
    ISSN: 0897-4756 , 1520-5002
    Language: English
    Publisher: American Chemical Society (ACS)
    Publication Date: 2008
    detail.hit.zdb_id: 1500399-1
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  • 8
    In: Journal of Neurology, Neurosurgery & Psychiatry, BMJ, Vol. 92, No. 8 ( 2021-08), p. A13.2-A14
    Abstract: The typical onset of Alzheimers Disease (AD) is characterised by episodic memory impairment. However, AD pathology can present with atypical clinical features and/or mixed aetiologies, which often lead to diagnostic uncertainty. Biomarker evaluation using amyloid PET imaging (API) in this group is guided by published appropriate use criteria (Johnson et al., 2013). A large proportion of these patients is also referred for clinical neuropsychological assessment. Here, we investigate the cognitive profiles and affective symptoms of memory clinic patients who are referred to both API and neuropsychological assessment as part of their diagnostic assessment. Methods From a larger group of 396 patients that underwent clinical API between December 2013 and June 2019 at the Imperial Memory Clinic, we included individuals who also had a formal neuropsychological assessment (minimum of 4 domains) within 18 months of API and who received subsequent follow-up at our clinic. Referrals to API were in line with the appropriate use criteria and took place after multidisciplinary team discussion. A total of 107 patients, 47 amyloid-positive (Aβ-pos) and 60 amyloid-negative (Aβ-neg), were included. The Aβ-neg group was further divided into progressive (progAβ-neg, n=26) and stable (stableAβ-neg, n=34), based on the presence or absence of documented clinical progression and/or concomitant neurological condition. Results The three groups were comparable for age and premorbid IQ, while there was a lower proportion of females in the stableAβ-neg group (table 1). ANCOVA models (with age, sex and premorbid IQ as covariates, and group as fixed factor) revealed that the Aβ-pos group performed worse than both negative groups in the domains of visuospatial and working memory (figure 1). The Aβ-pos group differed from the stableAβ-neg but not the progAβ-neg group on a measure of episodic memory (figure 1). The Hospital Anxiety and Depression scale (HADS) was administered to 85 patients (36 Aβ-pos, 20 progAβ-neg, 29 stableAβ-neg): non-parametric testing revealed higher levels of depressive symptoms in the stableAβ-neg group than in the Aβ-pos group (figure 2a). Notably, a significant proportion of patients reported clinical levels (HADS≥8) of anxiety and depression across all groups (figure 2b). Abstract #2977 Table 1 Demographic and general characteristics of the study sample Aβ-pos stableAβ-neg progAβ-neg Ageyears, meanSD 66.578.84 68.0310.48 66.588.71 PremorbidIQ, meanSD 101.2712.3 101.9313.45 100.9611.95 Gender, %female 61.70% 29.4% 50% Abstract #2977 Figure 1 (A) Unadjusted mean raw anxiety and depression scores as measured by the HADS. *adjusted p 〈 0.05; (B) Proportion of patients with clinically significant levels (HADS≥8) of anxiety and depression. Abstract #2977 Figure 2 Conclusions In a memory clinic cohort undergoing clinical amyloid PET imaging and neuropsychological assessment, visuospatial dysfunction and working memory impairment were better indicators of Alzheimers pathology than episodic memory dysfunction. Moreover, in this group we found a high prevalence of anxiety and depressive symptoms regardless of amyloid status. Loreto et al. Cognitive performance and affective symptoms in patients undergoing clinical Amyloid PET Imaging
    Type of Medium: Online Resource
    ISSN: 0022-3050 , 1468-330X
    RVK:
    Language: English
    Publisher: BMJ
    Publication Date: 2021
    detail.hit.zdb_id: 1480429-3
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  • 9
    In: Journal of Neurology, Neurosurgery & Psychiatry, BMJ, Vol. 92, No. 8 ( 2021-08), p. A9.1-A9
    Abstract: Depression has been reported as a possible risk factor for Alzheimer’s Disease, but also as one of the clinical features of Alzheimer’s as well as other dementias. Further, depression has long been associated with cognitive impairment in the absence of neurodegeneration (Connors et al . 2018). Here we sought to ascertain the prevalence of clinical depression in patients meeting widely accepted Appropriate Use Criteria for Amyloid PET Imaging (API). We examined the prevalence of lifetime depression in patients undergoing clinical API in a real-world clinical setting and compared our findings with population data from community-dwelling older adults. We also examined whether rates of depression were higher in amyloid positive or negative groups. Methods One-hundred-and-eighty-five older adults (mean age 67.079.37, 49% females) underwent diagnostic workup, including API, at the Imperial Memory Clinic between January 2017 and June 2019. API was performed in line with appropriate use criteria after multidisciplinary team discussion. History of depressive symptoms and features of depression were evaluated through a review of hospital records and clinical correspondence. Patients were defined as having a history of depression if there was evidence of previous or current depressive symptoms and/or of a formal diagnosis of depression in their clinical records. Results Based on visual reads, 83 individuals had positive Amyloid-PET scans and 102 were negative. Overall, 102 (55%) patients(mean age=66.758.99, 56% females) had a history of lifetime depressive symptoms, compared with just 12 and 19% of elderly individuals in the general population (McDougall et al. 2007; Biddulph et al. 2014). Of the 92 patients for whom further information regarding depression onset were available, 54 (58.7%) had early symptom onset (age 〈 60), and 38 (41.3%) had late symptom onset (age ≥s60). At the time of the clinical assessment at the Imperial Memory Clinic, 71 of those 102 (69.6%) were on active treatment for depression. Finally, depression was not associated with amyloid status (χ 2 (1) =1.12 p =.26), with 42 (41.2%) amyloid-positive and 60 (58.8%) amyloid-negative patients reporting a history of depression. Conclusions Over half of patients with suspected cognitive impairment and meeting appropriate use criteria for clinical API had a history of depression, regardless of amyloid status. Depression is an important but incompletely understood factor in referral for evaluation with Amyloid-PET.
    Type of Medium: Online Resource
    ISSN: 0022-3050 , 1468-330X
    RVK:
    Language: English
    Publisher: BMJ
    Publication Date: 2021
    detail.hit.zdb_id: 1480429-3
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  • 10
    Online Resource
    Online Resource
    Informa UK Limited ; 2005
    In:  Molecular Crystals and Liquid Crystals Vol. 429, No. 1 ( 2005-05), p. 65-76
    In: Molecular Crystals and Liquid Crystals, Informa UK Limited, Vol. 429, No. 1 ( 2005-05), p. 65-76
    Type of Medium: Online Resource
    ISSN: 1542-1406 , 1563-5287
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2005
    detail.hit.zdb_id: 2022536-2
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