- Email: [email protected]
Impairments of 3D visual perception in posterior cortical atrophy: Psychophysical, structural and functional anatomical basis
P524
Oral Sessions: O3-04: Diagnosis and Prognosis: Novel Neuropsychological Studies of Dementia
calculate the trajectory of each parameter over time. Results: At baseline significantly higher Ab burdens were observed in AD (2.360.4) and MCI (1.960.6) compared to HC (1.460.4). At follow up 163 (82%) of the 200 participants showed positive rates of beta-amyloid accumulation. Estimates of Ab deposition over time show it takes 19 (CI 17-23) years in an almost linear fashion - with increases averaging 0.043 (CI 0.0370.049) SUVR/yr-, to go from the threshold of PiB positivity (1.5 SUVR) to the levels observed in AD. Conversely, it takes 12 (CI 10-15 years) years to go from the levels observed in HC with low beta-amyloid (1.260.1 SUVR) to the threshold of PiB positivity. As AD progresses, the rate of beta-amyloid deposition slows, leaning towards a plateau. Our projections suggest a prolonged preclinical phase of AD where beta-amyloid deposition, hippocampal atrophy, and memory impairment become sequentially abnormal at 17 (CI 15-20), 4 (CI 4-5), and 3 (CI 3-5) years respectively, before the onset of dementia. Conclusions: Beta-amyloid deposition is a slow and protracted process, likely to extend for more than two decades. Predicting the rate of evolution of preclinical changes and the onset of clinical phase of AD are essential for the design and timing of therapeutic interventions aimed at modifying the course of this illness. ORAL SESSIONS: O3-04: DIAGNOSIS AND PROGNOSIS: NOVEL NEUROPSYCHOLOGICAL STUDIES OF DEMENTIA O3-04-01
IMPAIRMENTS OF 3D VISUAL PERCEPTION IN POSTERIOR CORTICAL ATROPHY: PSYCHOPHYSICAL, STRUCTURAL AND FUNCTIONAL ANATOMICAL BASIS
Celine R. Gillebert1, Christine Bastin2, Stefan Sunaert3, Eric Salmon4, James T. Todd5, Guy A. Orban6, Rik Vandenberghe7, 1University of Oxford, Oxford, United Kingdom; 2Cyclotron Research Centre, University of Liege, Liege, Belgium; 3University Hospitals Leuven, Leuven, Belgium; 4 Cyclotron Research Centre, University of Liege, Liege, Belgium; 5Ohio State University, Columbus, Ohio, United States; 6KU Leuven, Leuven, Belgium; 7University Hospitals Leuven and University of Leuven (KUL), Leuven, Belgium. Contact e-mail: [email protected] Background: Posterior cortical atrophy (PCA) is a relatively rare variant of Alzheimer’s disease characterized by predominantly visual disturbances early in the disease course. From a neurophysiological perspective these deficits and the underlying anatomical changes remain ill-defined. Our aim was to evaluate 3D perception in PCA for different cues and relate this to structural and functional changes on MRI. Methods: Eleven PCA patients in a relatively early disease stage participated as well as 30 agematched healthy controls and a patient control group of 9 clinically probable Lewy body disease patients (LBD). Using a hierarchical experimental design, our computerized psychophysical test battery evaluated 3D-fromshading, 3D-from-motion, 3D-from-texture and 3D-from ocular disparity, 2D processing from the same cues and elementary feature extraction. All
subjects underwent a volumetric MRI. Using linear regression, scores on 3D perception for each of the cues were correlated with grey matter volume within the network for 3D visual processing as defined in 18 of the healthy controls using fMRI. The fMRI encompassed epochs of passive visual stimulation of 3D-from-motion, 3D-from-shading and matched 2D control stimuli. Four of the PCA patients also underwent the fMRI. Their activity levels were compared to fMRI data obtained in the healthy controls. Results: 3D perception was impaired for shading, motion and texture in PCA and in LBD, with relative preservation of 3D-from-disparity. PCA patients showed extensive grey matter atrophy in occipital, posterior temporal and parietal regions. Within the 3D processing network, grey matter volume in right inferior temporal gyrus (x ¼ 39 mm, y ¼ -70, z ¼ -6, r ¼ 0.90, corrected voxellevel P ¼ 0.039) correlated with scores on 3D-from-shading within the PCA group. The correlation was specific for PCA and not present in LBD. It was also specific for shading as cue. fMRI activity levels in right inferior temporal gyrus were lower in 3 of the 4 PCA patients tested compared to controls. Conclusions: 3D perception is impaired in PCA and in LBD but the underlying mechanism is disease- and cue-specific. Amongst the extensive gray matter loss observed in PCA, our findings implicate right inferior temporal gyrus specifically in deficits of 3D-from-shading in PCA. O3-04-02
USING VISUAL ATTENTION TO DETECT APATHY IN ALZHEIMER’S DISEASE
Krista Lanct^ot1, Sarah Chau1, Moshe Eizenman2, Larry Grupp2, Nathan Herrmann3, 1Sunnybrook Research Institute, Toronto, Ontario, Canada; 2University of Toronto, Toronto, Ontario, Canada; 3Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada. Contact e-mail: krista. [email protected] Background: Apathy, one of the most prevalent neuropsychiatric symptoms in Alzheimer’s disease (AD), can be difficult to assess as cognition deteriorates. There is a need for more objective assessments that do not rely on patient insight, cognitive or communicative capacities, or caregiver observation. Our team developed the Visual Attention Scanning Technology (VAST), an eyetracker that measures attention patterns towards competing visual stimuli. We explored VAST as a novel method of assessing symptoms of apathy in AD. Methods: Mild-to-moderate AD patients (NINCDS-ADRDA; MiniMental Status Examination, MMSE>10) were assessed for apathy (Neuropsychiatric Inventory [NPI] apathy). Participants were presented with 16 slides, each containing 4 images of different themes (2 neutral, 1 social, 1 dysphoric), interspersed with filler slides. Patients were allowed 10.5 seconds to view each slide while VAST measured the length of time spent fixating on each image. Groups were compared using analysis of variance (ANOVA). Results: Of 25 AD patients (14 F, age¼76.5610.0, MMSE¼22.863.0) included in this preliminary analysis, 12 had significant apathy (NPI apathy 4). These patients had comparable age and MMSE. Non-apathetic controls demonstrated a preference for social images compared with apathetic patients (F¼0.34, p¼0.03). Within the non-apathetic group, patients fixated longer on social compared with neutral and dysphoric images (F¼13.26, p<<0.001). Within the apathetic group, patients showed preference for both social and dysphoric compared with neutral images (F¼13.35, p<<0.001), with a trend of longer fixations on dysphoric compared with social images (F¼3.99, p¼0.06). Conclusions: VAST has shown the ability to differentiate between apathetic and non-apathetic patients. In addition, VAST was able to generate a unique attentional bias profile within these groups. These results improve our understanding of attention bias in AD and may have the potential to predict and monitor treatment response in apathy. O3-04-03
THE COCKTAIL PARTY EFFECT IN ALZHEIMER’S DISEASE
Hannah Golden, Jennifer Agustus, Joanna Goll, Keir Yong, Laura Downey, Sebastian Crutch, Jason Warren, University College London, London, United Kingdom. Contact e-mail: [email protected] Background: Parsing the sound sources around us into a coherent representation of the auditory world is a challenging computational problem. Such auditory scene analysis (ASA) is exemplified in the familiar ’cocktail party effect’ where we automatically hear our own name spoken across a crowded
Oral Sessions: O3-04: Diagnosis and Prognosis: Novel Neuropsychological Studies of Dementia
calculate the trajectory of each parameter over time. Results: At baseline significantly higher Ab burdens were observed in AD (2.360.4) and MCI (1.960.6) compared to HC (1.460.4). At follow up 163 (82%) of the 200 participants showed positive rates of beta-amyloid accumulation. Estimates of Ab deposition over time show it takes 19 (CI 17-23) years in an almost linear fashion - with increases averaging 0.043 (CI 0.0370.049) SUVR/yr-, to go from the threshold of PiB positivity (1.5 SUVR) to the levels observed in AD. Conversely, it takes 12 (CI 10-15 years) years to go from the levels observed in HC with low beta-amyloid (1.260.1 SUVR) to the threshold of PiB positivity. As AD progresses, the rate of beta-amyloid deposition slows, leaning towards a plateau. Our projections suggest a prolonged preclinical phase of AD where beta-amyloid deposition, hippocampal atrophy, and memory impairment become sequentially abnormal at 17 (CI 15-20), 4 (CI 4-5), and 3 (CI 3-5) years respectively, before the onset of dementia. Conclusions: Beta-amyloid deposition is a slow and protracted process, likely to extend for more than two decades. Predicting the rate of evolution of preclinical changes and the onset of clinical phase of AD are essential for the design and timing of therapeutic interventions aimed at modifying the course of this illness. ORAL SESSIONS: O3-04: DIAGNOSIS AND PROGNOSIS: NOVEL NEUROPSYCHOLOGICAL STUDIES OF DEMENTIA O3-04-01
IMPAIRMENTS OF 3D VISUAL PERCEPTION IN POSTERIOR CORTICAL ATROPHY: PSYCHOPHYSICAL, STRUCTURAL AND FUNCTIONAL ANATOMICAL BASIS
Celine R. Gillebert1, Christine Bastin2, Stefan Sunaert3, Eric Salmon4, James T. Todd5, Guy A. Orban6, Rik Vandenberghe7, 1University of Oxford, Oxford, United Kingdom; 2Cyclotron Research Centre, University of Liege, Liege, Belgium; 3University Hospitals Leuven, Leuven, Belgium; 4 Cyclotron Research Centre, University of Liege, Liege, Belgium; 5Ohio State University, Columbus, Ohio, United States; 6KU Leuven, Leuven, Belgium; 7University Hospitals Leuven and University of Leuven (KUL), Leuven, Belgium. Contact e-mail: [email protected] Background: Posterior cortical atrophy (PCA) is a relatively rare variant of Alzheimer’s disease characterized by predominantly visual disturbances early in the disease course. From a neurophysiological perspective these deficits and the underlying anatomical changes remain ill-defined. Our aim was to evaluate 3D perception in PCA for different cues and relate this to structural and functional changes on MRI. Methods: Eleven PCA patients in a relatively early disease stage participated as well as 30 agematched healthy controls and a patient control group of 9 clinically probable Lewy body disease patients (LBD). Using a hierarchical experimental design, our computerized psychophysical test battery evaluated 3D-fromshading, 3D-from-motion, 3D-from-texture and 3D-from ocular disparity, 2D processing from the same cues and elementary feature extraction. All
subjects underwent a volumetric MRI. Using linear regression, scores on 3D perception for each of the cues were correlated with grey matter volume within the network for 3D visual processing as defined in 18 of the healthy controls using fMRI. The fMRI encompassed epochs of passive visual stimulation of 3D-from-motion, 3D-from-shading and matched 2D control stimuli. Four of the PCA patients also underwent the fMRI. Their activity levels were compared to fMRI data obtained in the healthy controls. Results: 3D perception was impaired for shading, motion and texture in PCA and in LBD, with relative preservation of 3D-from-disparity. PCA patients showed extensive grey matter atrophy in occipital, posterior temporal and parietal regions. Within the 3D processing network, grey matter volume in right inferior temporal gyrus (x ¼ 39 mm, y ¼ -70, z ¼ -6, r ¼ 0.90, corrected voxellevel P ¼ 0.039) correlated with scores on 3D-from-shading within the PCA group. The correlation was specific for PCA and not present in LBD. It was also specific for shading as cue. fMRI activity levels in right inferior temporal gyrus were lower in 3 of the 4 PCA patients tested compared to controls. Conclusions: 3D perception is impaired in PCA and in LBD but the underlying mechanism is disease- and cue-specific. Amongst the extensive gray matter loss observed in PCA, our findings implicate right inferior temporal gyrus specifically in deficits of 3D-from-shading in PCA. O3-04-02
USING VISUAL ATTENTION TO DETECT APATHY IN ALZHEIMER’S DISEASE
Krista Lanct^ot1, Sarah Chau1, Moshe Eizenman2, Larry Grupp2, Nathan Herrmann3, 1Sunnybrook Research Institute, Toronto, Ontario, Canada; 2University of Toronto, Toronto, Ontario, Canada; 3Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada. Contact e-mail: krista. [email protected] Background: Apathy, one of the most prevalent neuropsychiatric symptoms in Alzheimer’s disease (AD), can be difficult to assess as cognition deteriorates. There is a need for more objective assessments that do not rely on patient insight, cognitive or communicative capacities, or caregiver observation. Our team developed the Visual Attention Scanning Technology (VAST), an eyetracker that measures attention patterns towards competing visual stimuli. We explored VAST as a novel method of assessing symptoms of apathy in AD. Methods: Mild-to-moderate AD patients (NINCDS-ADRDA; MiniMental Status Examination, MMSE>10) were assessed for apathy (Neuropsychiatric Inventory [NPI] apathy). Participants were presented with 16 slides, each containing 4 images of different themes (2 neutral, 1 social, 1 dysphoric), interspersed with filler slides. Patients were allowed 10.5 seconds to view each slide while VAST measured the length of time spent fixating on each image. Groups were compared using analysis of variance (ANOVA). Results: Of 25 AD patients (14 F, age¼76.5610.0, MMSE¼22.863.0) included in this preliminary analysis, 12 had significant apathy (NPI apathy 4). These patients had comparable age and MMSE. Non-apathetic controls demonstrated a preference for social images compared with apathetic patients (F¼0.34, p¼0.03). Within the non-apathetic group, patients fixated longer on social compared with neutral and dysphoric images (F¼13.26, p<<0.001). Within the apathetic group, patients showed preference for both social and dysphoric compared with neutral images (F¼13.35, p<<0.001), with a trend of longer fixations on dysphoric compared with social images (F¼3.99, p¼0.06). Conclusions: VAST has shown the ability to differentiate between apathetic and non-apathetic patients. In addition, VAST was able to generate a unique attentional bias profile within these groups. These results improve our understanding of attention bias in AD and may have the potential to predict and monitor treatment response in apathy. O3-04-03
THE COCKTAIL PARTY EFFECT IN ALZHEIMER’S DISEASE
Hannah Golden, Jennifer Agustus, Joanna Goll, Keir Yong, Laura Downey, Sebastian Crutch, Jason Warren, University College London, London, United Kingdom. Contact e-mail: [email protected] Background: Parsing the sound sources around us into a coherent representation of the auditory world is a challenging computational problem. Such auditory scene analysis (ASA) is exemplified in the familiar ’cocktail party effect’ where we automatically hear our own name spoken across a crowded