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Posterior Cortical Atrophy
The visual variant of Alzheimer’s Disease Josée Rivest, Ph.D., C.Psych. Baycrest: Neuropsychology and Cognitive Health Program York University: Psychology, Glendon College Centre for Vision Research October 6, 2014
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Objectives Outline Learn what is Posterior Cortical Atrophy (PCA)
Establish parallels with the visual system Compare PCA and AD Outline Review —The Visual System: Anatomy & Cognitive Deficits Posterior Cortical Atrophy: Syndrome Parallel with the anatomy of the visual system Case presentation: Data over 4 years
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Visual System Dorsal and Ventral Streams Dorsal stream:
Modular organization Dorsal and Ventral Streams ACTION Dorsal stream: Where/How system Motion Form & Color Ventral stream: What system RECOGNITION Ungerleider, L.G., Mishkin, M. (1982). Two cortical visual systems. Cambridge (MA): MIT Press p Goodale, M.A., Milner, A.D. (1992). Separate visual pathways for perception and action. Trends in Neurosciences. 15:20-25.
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Dorsal Stream Ventral Stream
Spatial aspects (where) Shape Pattern Texture Color “The visual brain in action” (Miller & Goodale, 1995, 2006) Vision for action Egocentric coding Transient representations Independent of awareness Vision for perception (recognition) Allocentric coding Sustained representations Critically linked to awareness Schenk, T., & Mcintosh, R. D. (2010). Discussion Paper: Do we have independent visual streams for perception and action? Cognitive Neuroscience, 1(1),
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Damaged Dorsal Stream Visual neglect Visuo-motor impairment (optic ataxia) Extinction Simultagnosia Apraxia Akineotopsia (motion blindness) Spatial dysperception (e.g. depth, length, size) Hand-eye incoordination Finger agnosia Right-left confusion Dysgraphia/agraphia: writing Dyscalculia/acalculia: math
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Damaged Dorsal Stream Bálint syndrome
• Ocular apraxia: Inability to voluntarily look around in space • Optic ataxia: Inability to reach for an object under visual guidance • Simultagnosia Gerstmann syndrome • Agraphia • Acalculia • Finger agnosia • Left-right disorientation
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Damaged Ventral Stream
Object agnosia Prosopagnosia Alexia Achromatopsia
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Neurodegenerative syndrome
Posterior Cortical Atrophy Neurodegenerative syndrome Termed in 1988 by Benson et al. “Visual variant of AD; Biparietal AD; Benson syndrome” Skills Declined: Preserved: Visuo-spatial Visuo-perceptual Literacy Praxic Language Memory Insight Non Verbal IQ < Verbal IQ Benson, D.F., Davis, R.J. Snyder, B.D. (1988). Posterior Cortical Atrophy. Arch. Neurol., 45,
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Posterior Cortical Atrophy
Clinical presentation • Depressive symptoms: tearfulness sadness insomnia loss of weight • Non-specific visual complaints: Poor vision: optometry, ophthalmology: “nothing is wrong”
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Posterior Cortical Atrophy
Neuropsychological features • Visuo-spatial & visuo-perceptual impairments • Alexia • Bàlint’s syndrome: Simultagnosia Oculomotor apraxia Optic ataxia • Gerstmann’s syndrome: Acalculia Agraphia Finger agnosia Left-right disorientation
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Posterior Cortical Atrophy
Neuropsychological features • Prosopagnosia • Achromatopsia • Visual field defects • Hemineglect • Constructional dyspraxia • Apraxia - dressing - ideomotor: imitate hand gestures and voluntarily pantomime tool use • Working memory
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Posterior Cortical Atrophy
Epidemiology Unknown: underestimation • AD n=523 5% PCA (Snowden et al., 2007) • No gender difference • Age of onset: years Snowden, J.S., Stopford, C.L., Julien, C.L. et al. (2007). Cognitive phenotypes in Alzheimer's disease and genetic risk. Cortex, 43(7),
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Alzheimer’s Disease • 60-80% of all dementia cases
• Age of onset: > 65 years • Prevalence • < 65 4% of population • 6% • 46% **** > 65 13% **** • Women > Men The global prevalence of dementia has been estimated to be as high as 24 million, and is predicted to double every 20 years until at least 2040.
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University Health Network Memory clinic
Posterior Cortical Atrophy Pathologic heterogeneity Dr. David Tang-Wai University Health Network Memory clinic Causes: • Alzheimer’s disease: senile plaques & neurofibrillary tangles • Dementia with Lewy bodies • Corticobasal degeneration • Prion disease (Creutzfeldt-Jacob disease & Fatal-familial insomnia –transmissible spongiform encephalopathies) Tang-Wai, D.F. & Graff-Radford, N.R. (2011). Looking into posterior cortical atrophy. Providing insight into Alzheimer disease. Neurology, 76,
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Posterior Cortical Atrophy
Atrophy or metabolic changes in the posterior regions: Parietal, Occipital, & Occipito-temporal cortices Prominent widening of the parietal and lateral occipital sulci 3D MRI reconstruction and selected coronal sections of the brain of a PCA patient Tang-Wai, D.F. & Graff-Radford, N.R. (2011). Looking into posterior cortical atrophy. Providing insight into Alzheimer disease. Neurology, 76,
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SPECT: 39 PCA, 24 AD & 24 controls
PCA: Extensive & symmetrical hypoperfusion in the occipital, parietal & posterior temporal cortices AD: Hypoperfusion in posterior associative cortex, prefrontal cortex & bilateral hippocampus Kas, A., de Souza, L. C., Samri, D., Bartolomeo, P., Lacomblez, L., et al. (2011). Neural correlates of cognitive impairment in posterior cortical atrophy. Brain, 134, doi: /brain/awr055.
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PCA: more hypoperfusion in the parieto-occipital cortex (blue)
More higher perfusion in the frontal, anterior cingulate, inferior & medial temporal regions (red) than AD Kas et al. (2011)
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Posterior Cortical Atrophy
Different forms? • Basic visual processing (striate cortex; caudal) form • Ventral form • Dorsal form Lehmann, M., Barnes, J. Ridgway, G.R., Wattam-Bell, J., Warrington, E.K., Fox, N.C. & Crutch, S. J. (2011). Basic visual function and cortical thickness patterns in posterior cortical atrophy. Cerebral Cortex, 21, Participants: N=20 PCA; n=20 matched controls TASKS (basic visual functions): Form detection Form coherence Form discrimination Color discrimination Motion coherence Point localization Related to: • Recognition (ventral form)? • Action/Space (dorsal form)?
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Cortical thickness PCA > Controls Cortical thickness
Lehmann, et al. (2011)
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Findings 1. Each PCA participant impaired on at least one basic visual processing task 2. Heterogeneity within the basic visual processing capacities 3. Type of basic visual processing dysfunction: • Impact upon the nature of their higher-order visual dysfunctions: —form detection, form coherence, & color performance object and space perception —form detection object but not space perception —point localization space but not object perception • No impact upon nonvisual parietal functions (e.g. calculation & spelling) • No correlation with recognition memory, MMSE, or disease duration Lehmann, et al. (2011)
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ANATOMY Space subgroup greater posterior parietal cortical thinning?
Object subgroup greater inferior temporal cortical thinning? Space (dorsal) PCA vs. Controls Object (ventral) PCA vs. Controls Cortical thickness PCA > Controls Cortical thickness PCA < Controls Lehmann, et al. (2011)
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Findings Space subgroup thinning in the occipital & inferior parietal lobes Object subgroup thinning in the fusiform gyrus & inferior temporal lobe Object (ventral) vs. Space (dorsal) Cortical thickness Space > Object Cortical thickness Space < Object BUT NO significant difference multiple common areas of tissue loss across the subgroups Lehmann, et al. (2011)
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Posterior Cortical Atrophy
Different forms? • Basic visual processing (striate cortex; caudal) form? — one dysfunction • Ventral form • Dorsal form Continuous range of object-space difference Lehmann, M., Barnes, J. Ridgway, G.R., Wattam-Bell, J., Warrington, E.K., Fox, N.C. & Crutch, S. J. (2011). Basic visual function and cortical thickness patterns in posterior cortical atrophy. Cerebral Cortex, 21,
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Case presentation: GB Medical history: • 79 year old man
• Born in New Zealand • Immigrated in Canada in 1962; Specialized MD (retired) • Lives with his wife & has 2 healthy children • Red/green color deficiency • Hobbies: reading, music, theatre, golf Medical history: • Myelodysplasia (bone marrow malfunction insufficient number of normal blood cells) • Arrhythmia • Prostate cancer • Pneumonia • Hypercholesterolemia
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GB Complaints (2010) • Reading** (even after cataract surgery)
• Word finding difficulties Neurology • Dr. Tang Way: MRI ( ): enlargement of cortical sulci and lateral ventricles (cerebral atrophy) Neuropsychology • cognitive profile followed yearly since 2010 Reading described as: slow, effortful, inefficient, not automatic, still reads books but much slower and tiresome Decrease of self confidence Could write and speak
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GB 2011
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GB 2012
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GB 2012
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Kaplan–Baycrest Neurocognitive Assessment (KBNA)
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Mean KBNA index scores of Group Dementia and Control expressed as (M = 50, SD = 10).
Mean KBNA index scores of Group Dementia and Control expressed as (M = 50, SD = 10). Error bars represent 95% confidence intervals. Abbreviations: AC = Attention/Concentration; MIR = Memory-Immediate Recall; MD = Memory-Delayed Recall; MDRec = Memory-Delayed Recognition; SP = Spatial Processing; VF = Verbal Fluency; RCS = Reasoning/Conceptual shifting; TI = Total Index. Leach L Arch Clin Neuropsychol 2010;25: © The Author Published by Oxford University Press. All rights reserved. For permissions, please
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Results GB: Cognitive Profile KBNA Verbal IQ Verbal memory
Verbal fluency Non-Verbal IQ Visual memory June 2011
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GB: Cognitive Profile Results June 2011 KBNA December 2011
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GB: very superior IQ (VIQ: 143; PIQ: 120)
Consistent with IQ Average Low average; Borderline Executive functions • Concept formation/ Mental flexibility • Alternating concepts Attention • Motor speed • Auditory divided • Visual automatic (accuracy) • Auditory selective • Visual controlled (accuracy) • Speed of visual attention Learning & Memory • Verbal memory • Visual memory • Visuo-motor working memory Not deep alexia: better reading of content words (e.g. nouns & verbs) than functors (e.g. prepositions): Grammatical class reading from PALPA – missed 3 nouns and 2 verbs – thus not deep alexia Language functions • Speech • Auditory comprehension • Written expression • Naming to visual confrontation • Reading (letter-by-letter reader)
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December 2011
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Immediate recall December 2011
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GB: Visuo-Perceptual Assessment
Normal Lower than expected Impaired • Visuo-constructional abilities (slow) • Reading (letter-by-letter) • Finger localization • Face matching (slow) • Praxis & Reaching • Picture naming (black & white drawings) • Stereopsis • Recognition of silhouettes • Judgment of line orientation • Object decision • No sensory extinction • Visual puzzles • Space perception • Visual search & scanning slow & found more objects on the left side • Writing Not deep alexia: better reading of content words (e.g. nouns & verbs) than functors (e.g. prepositions): Grammatical class reading from PALPA – missed 3 nouns and 2 verbs – thus not deep alexia • Object recognition • Foreshortened match (canonical vs. non canonical/ another object) • Item match (leaf vs. leaf/flower) • Association match (car vs. road/train track) • Copy
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X √ Birmingham Object Recognition Battery (BORB) Foreshortened match
Object decision
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Hooper Visual Organization Test
X Visual Puzzles
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Visual Object and Space Perception Battery (VOSP)
√ X X X
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Visual Object and Space Perception Battery (VOSP)
√ √ √ √
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Benton Face Recognition Test
√ X
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2013 GB: 2010 2011 2012 No difference Decline
• Cognitive flexibility • Processing speed • Perceptual reasoning • Visual scanning & attention • Verbal memory • Focused attention: slower • Visuo-constructional abilities • Reading • Spoken language • Face matching: slower & more hesitant • Praxis • Object recognition Not deep alexia: better reading of content words (e.g. nouns & verbs) than functors (e.g. prepositions): Grammatical class reading from PALPA – missed 3 nouns and 2 verbs – thus not deep alexia • Verbal fluency • Working memory • Visual memory
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KBNA
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Now… Boston Naming Test X
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June Assessment Verbal reasoning – WASI:Similarities Working memory – WAIS: Digit Span -- Arithmetic (oral) Attention/ Concentration VERBAL MEMORY Verbal Learning Delayed Verbal Recall Delayed Verbal Recognition Language –Auditory Comprehension & Repetition Praxis (Transitive, Intransitive & Buccofacial) Practical Reasoning Expression of emotions
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June 2014 —RESULTS Verbal reasoning – WASI:Similarities DECLINE:
Working memory – WAIS: Digit Span -- Arithmetic Attention/ Concentration: Disorientated to the year, month, day & time VERBAL MEMORY Verbal Learning Delayed Verbal Recall Delayed Verbal Recognition Average-High Average Language –Auditory Comprehension & Repetition Praxis (Transitive, Intransitive & Buccofacial) Practical Reasoning Expression of emotions DECLINE: borderline/impaired Unchanged
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KBNA 2014
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Posterior Cortical Atrophy
Review Article Crutch, S.J., Lehmann, M.S., Rabinovici, G. D., Rossor, M.N., & Fox, N.C. (2012). Posterior Cortical Atrophy. Lancet Neurology, 11, Borruat, F.-X. (2013). Posterior Cortical Atrophy: Review of the Recent Literature. Curr. Neurol. Neurosci. Rep., , 2-8.
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Thank you Dr. Dmytro Rewilak Dr. Kathy Stokes
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Tang-Wai & Petersen (amongst others) in 2006 recommended the following as diagnostic criteria:
Core: Insidious onset and gradual progression Presentation of visual complaints in absence of significant primary ocular disease Disabling visual impairment throughout disorder Absence of stroke or tumour Absence of early parkinsonism and hallucinations
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Any of the following: Simultanagnosia (with or without optic ataxia or ocular apraxia) Constructional dyspraxia Visual field defect Environmental disorientation Any of the elements of Gerstmann syndrome
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Supportive features: Investigations: Alexia Presenile onset
Ideomotor or dressing apraxia Prosopagnosia Investigations: Neuropsychological deficits due to parietal and/or occipital involvement Focal or asymmetric atrophy in parietal and/or occipital regions on structural imaging Focal or asymmetric hypoperfusion/ hypo-metabolism in parietal and/or occipital regions on functional imaging
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December 2011
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Occipitotemporal (Ventral) subgroup
Manifest either impairments in basic visual abilities (primary visual cortex involved), or Disruption of ventral stream of higher order visual processing, vital for object, face and written word identification Symptoms/findings of object agnosia, alexia, Gerstmann’s syndrome (agraphia, acalculia, R-L confusion, finger agnosia), simultanagnosia, possibly impaired colour vision and stereopsis, visual extinction, restricted visual fields
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Bi-parietal (Dorsal) subgroup
Typically have intact visual fields, basic perceptual abilities, object recognition and reading Disruption of dorsal stream of visuomotor processing critical for object location and visually guided movements Reflects also damage to parietal areas involved with general motor programming and writing Symptoms/findings of Balint’s syndrome, visuospatial difficulty, agraphia and dyspraxia
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Primary Visual subgroup
Less frequent Affects primary visual cortex Reflected in impairment of basic perceptual abilities, restricted visual fields
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GB: Visuo-Perceptual assessment
Normal Impaired Object processing (recognition & matching) Birmingham Object Recognition Battery (BORB) • Picture naming (animate drawings) • Picture naming (inanimate drawings) • Foreshortened match (canonical vs. non canonical/ another object) • Object decision • Item match (leaf vs. leaf/flower) • Association match (car vs. road/train track) • Copy Not deep alexia: better reading of content words (e.g. nouns & verbs) than functors (e.g. prepositions): Grammatical class reading from PALPA – missed 3 nouns and 2 verbs – thus not deep alexia Visual Object and Space Perception Battery (VOSP) • Shape detection • Incomplete letters • Silhouettes • Object decision • Hooper Visual Organization Test
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Cortical thickness PCA (n=48) tAD (n=30) PCA: • Greater density of senile plaques & neurofibrillary tangles in occipital, posterior parietal, & temporo-occipital cortex • Fewer pathological changes in more anterior areas such as prefrontal cortex Cortical thickness PCA > tAD Cortical thickness PCA < tAD Lehmann M, Crutch SJ, Ridgway GR et al. (2009). Cortical thickness and voxel-based morphometry in posterior cortical atrophy and typical Alzheimer's disease. Neurobiology of Aging. doi: /j.neurobiolaging
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Expectations Space subgroup greater posterior parietal cortical thinning Object subgroup greater inferior temporal cortical thinning Space (dorsal) PCA vs. Controls Object (ventral) PCA vs. Controls Cortical thickness PCA > Controls Cortical thickness PCA < Controls Lehmann, et al. (2011)
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Immediate recall June 2011
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June 2011
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