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1.  Genetic modifiers in carriers of repeat expansions in the C9ORF72 gene 
Hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9ORF72) are causative for frontotemporal dementia (FTD) and motor neuron disease (MND). Substantial phenotypic heterogeneity has been described in patients with these expansions. We set out to identify genetic modifiers of disease risk, age at onset, and survival after onset that may contribute to this clinical variability.
We examined a cohort of 330 C9ORF72 expansion carriers and 374 controls. In these individuals, we assessed variants previously implicated in FTD and/or MND; 36 variants were included in our analysis. After adjustment for multiple testing, our analysis revealed three variants significantly associated with age at onset (rs7018487 [UBAP1; p-value = 0.003], rs6052771 [PRNP; p-value = 0.003], and rs7403881 [MT-Ie; p-value = 0.003]), and six variants significantly associated with survival after onset (rs5848 [GRN; p-value = 0.001], rs7403881 [MT-Ie; p-value = 0.001], rs13268953 [ELP3; p-value = 0.003], the epsilon 4 allele [APOE; p-value = 0.004], rs12608932 [UNC13A; p-value = 0.003], and rs1800435 [ALAD; p-value = 0.003]).
Variants identified through this study were previously reported to be involved in FTD and/or MND, but we are the first to describe their effects as potential disease modifiers in the presence of a clear pathogenic mutation (i.e. C9ORF72 repeat expansion). Although validation of our findings is necessary, these variants highlight the importance of protein degradation, antioxidant defense and RNA-processing pathways, and additionally, they are promising targets for the development of therapeutic strategies and prognostic tests.
Electronic supplementary material
The online version of this article (doi:10.1186/1750-1326-9-38) contains supplementary material, which is available to authorized users.
PMCID: PMC4190282  PMID: 25239657
C9ORF72; Frontotemporal dementia; Motor neuron disease; Genetic modifier; Repeat expansion
2.  Psychosis and Hallucinations in FTD with C9ORF72 mutation: A detailed clinical cohort 
To describe in detail the presenting symptoms and clinical course of a cohort of patients with Frontotemporal dementia and the recently described C9ORF72 repeat expansion.
Recent discovery of the C9ORF72 repeat expansion linked to familial frontotemporal dementia and ALS has permitted retrospective evaluation of potential defining clinical characteristics that may distinguish C9ORF72 mutation carriers from other patients with FTD. Prior reports have identified a subset of patients with an increased incidence of psychosis, specifically delusions, though the detailed nature of these symptoms is not yet well described.
We conducted a retrospective chart review of to report the detailed case histories of 7 patients with C9ORF72 mutations from a cohort of 61 patients with FTD.
Detailed histories available from these patients reveal an increased incidence of psychosis, including visual and auditory hallucinations and delusions compared to sporadic FTD patients in our cohort.
This cohort confirms and adds symptom-related details to prior reports of increased incidence of psychotic phenomenon in FTD and ALS patients with C9ORF72 mutations, to enhance future clinical identification and diagnosis of patients presenting with these symptoms.
PMCID: PMC4090685  PMID: 24077574
frontotemporal dementia; psychosis; C9ORF72 mutation; motor neuron disease
3.  C9ORF72 repeat expansions in cases with previously identified pathogenic mutations 
Neurology  2013;81(15):1332-1341.
To identify potential genetic modifiers contributing to the phenotypic variability that is detected in patients with repeat expansions in chromosome 9 open reading frame 72 (C9ORF72), we investigated the frequency of these expansions in a cohort of 334 subjects previously found to carry mutations in genes known to be associated with a spectrum of neurodegenerative diseases.
A 2-step protocol, with a fluorescent PCR and a repeat-primed PCR, was used to determine the presence of hexanucleotide expansions in C9ORF72. For one double mutant, we performed Southern blots to assess expansion sizes, and immunohistochemistry to characterize neuropathology.
We detected C9ORF72 repeat expansions in 4 of 334 subjects (1.2% [or 1.8% of 217 families]). All these subjects had behavioral phenotypes and also harbored well-known pathogenic mutations in either progranulin (GRN: p.C466LfsX46, p.R493X, p.C31LfsX35) or microtubule-associated protein tau (MAPT: p.P301L). Southern blotting of one double mutant with a p.C466LfsX46 GRN mutation demonstrated a long repeat expansion in brain (>3,000 repeats), and immunohistochemistry showed mixed neuropathology with characteristics of both C9ORF72 expansions and GRN mutations.
Our findings indicate that co-occurrence of 2 evidently pathogenic mutations could contribute to the pleiotropy that is detected in patients with C9ORF72 repeat expansions. These findings suggest that patients with known mutations should not be excluded from further studies, and that genetic counselors should be aware of this phenomenon when advising patients and their family members.
PMCID: PMC3806926  PMID: 24027057
4.  Criteria for the diagnosis of corticobasal degeneration 
Neurology  2013;80(5):496-503.
Current criteria for the clinical diagnosis of pathologically confirmed corticobasal degeneration (CBD) no longer reflect the expanding understanding of this disease and its clinicopathologic correlations. An international consortium of behavioral neurology, neuropsychology, and movement disorders specialists developed new criteria based on consensus and a systematic literature review. Clinical diagnoses (early or late) were identified for 267 nonoverlapping pathologically confirmed CBD cases from published reports and brain banks. Combined with consensus, 4 CBD phenotypes emerged: corticobasal syndrome (CBS), frontal behavioral-spatial syndrome (FBS), nonfluent/agrammatic variant of primary progressive aphasia (naPPA), and progressive supranuclear palsy syndrome (PSPS). Clinical features of CBD cases were extracted from descriptions of 209 brain bank and published patients, providing a comprehensive description of CBD and correcting common misconceptions. Clinical CBD phenotypes and features were combined to create 2 sets of criteria: more specific clinical research criteria for probable CBD and broader criteria for possible CBD that are more inclusive but have a higher chance to detect other tau-based pathologies. Probable CBD criteria require insidious onset and gradual progression for at least 1 year, age at onset ≥50 years, no similar family history or known tau mutations, and a clinical phenotype of probable CBS or either FBS or naPPA with at least 1 CBS feature. The possible CBD category uses similar criteria but has no restrictions on age or family history, allows tau mutations, permits less rigorous phenotype fulfillment, and includes a PSPS phenotype. Future validation and refinement of the proposed criteria are needed.
PMCID: PMC3590050  PMID: 23359374
5.  Length of normal alleles of C9ORF72 GGGGCC repeat do not influence disease phenotype 
Neurobiology of aging  2012;33(12):2950.e5-2950.e7.
Expansions of the non-coding GGGGCC hexanucleotide repeat in the chromosome 9 open reading frame 72 (C9ORF72) gene were recently identified as the long sought-after cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) on chromosome 9p. In this study we aimed to determine whether the length of the normal - unexpanded - allele of the GGGGCC repeat in C9ORF72 plays a role in the presentation of disease or affects age at onset in C9ORF72 mutation carriers. We also studied whether the GGGGCC repeat length confers risk or affects age at onset in FTD and ALS patients without C9ORF72 repeat expansions. C9ORF72 genotyping was performed in 580 FTD, 995 ALS and 160 FTD-ALS patients and 1444 controls, leading to the identification of 211 patients with pathogenic C9ORF72 repeat expansions and an accurate quantification of the length of the normal alleles in all patients and controls. No meaningful association between the repeat length of the normal alleles of the GGGGCC repeat in C9ORF72 and disease phenotype or age at onset was observed in C9ORF72 mutation carriers or non-mutation carriers.
PMCID: PMC3617405  PMID: 22840558
Amyotrophic lateral sclerosis; Frontotemporal Dementia; C9ORF72; Repeat-expansion disease; Association study
6.  Evidence for a role of the rare p.A152T variant in MAPT in increasing the risk for FTD-spectrum and Alzheimer's diseases 
Coppola, Giovanni | Chinnathambi, Subashchandrabose | Lee, Jason JiYong | Dombroski, Beth A. | Baker, Matt C. | Soto-Ortolaza, Alexandra I. | Lee, Suzee E. | Klein, Eric | Huang, Alden Y. | Sears, Renee | Lane, Jessica R. | Karydas, Anna M. | Kenet, Robert O. | Biernat, Jacek | Wang, Li-San | Cotman, Carl W. | DeCarli, Charles S. | Levey, Allan I. | Ringman, John M. | Mendez, Mario F. | Chui, Helena C. | Le Ber, Isabelle | Brice, Alexis | Lupton, Michelle K. | Preza, Elisavet | Lovestone, Simon | Powell, John | Graff-Radford, Neill | Petersen, Ronald C. | Boeve, Bradley F. | Lippa, Carol F. | Bigio, Eileen H. | Mackenzie, Ian | Finger, Elizabeth | Kertesz, Andrew | Caselli, Richard J. | Gearing, Marla | Juncos, Jorge L. | Ghetti, Bernardino | Spina, Salvatore | Bordelon, Yvette M. | Tourtellotte, Wallace W. | Frosch, Matthew P. | Vonsattel, Jean Paul G. | Zarow, Chris | Beach, Thomas G. | Albin, Roger L. | Lieberman, Andrew P. | Lee, Virginia M. | Trojanowski, John Q. | Van Deerlin, Vivianna M. | Bird, Thomas D. | Galasko, Douglas R. | Masliah, Eliezer | White, Charles L. | Troncoso, Juan C. | Hannequin, Didier | Boxer, Adam L. | Geschwind, Michael D. | Kumar, Satish | Mandelkow, Eva-Maria | Wszolek, Zbigniew K. | Uitti, Ryan J. | Dickson, Dennis W. | Haines, Jonathan L. | Mayeux, Richard | Pericak-Vance, Margaret A. | Farrer, Lindsay A. | Ross, Owen A. | Rademakers, Rosa | Schellenberg, Gerard D. | Miller, Bruce L. | Mandelkow, Eckhard | Geschwind, Daniel H.
Human Molecular Genetics  2012;21(15):3500-3512.
Rare mutations in the gene encoding for tau (MAPT, microtubule-associated protein tau) cause frontotemporal dementia-spectrum (FTD-s) disorders, including FTD, progressive supranuclear palsy (PSP) and corticobasal syndrome, and a common extended haplotype spanning across the MAPT locus is associated with increased risk of PSP and Parkinson's disease. We identified a rare tau variant (p.A152T) in a patient with a clinical diagnosis of PSP and assessed its frequency in multiple independent series of patients with neurodegenerative conditions and controls, in a total of 15 369 subjects.
Tau p.A152T significantly increases the risk for both FTD-s (n = 2139, OR = 3.0, CI: 1.6–5.6, P = 0.0005) and Alzheimer's disease (AD) (n = 3345, OR = 2.3, CI: 1.3–4.2, P = 0.004) compared with 9047 controls. Functionally, p.A152T (i) decreases the binding of tau to microtubules and therefore promotes microtubule assembly less efficiently; and (ii) reduces the tendency to form abnormal fibers. However, there is a pronounced increase in the formation of tau oligomers. Importantly, these findings suggest that other regions of the tau protein may be crucial in regulating normal function, as the p.A152 residue is distal to the domains considered responsible for microtubule interactions or aggregation. These data provide both the first genetic evidence and functional studies supporting the role of MAPT p.A152T as a rare risk factor for both FTD-s and AD and the concept that rare variants can increase the risk for relatively common, complex neurodegenerative diseases, but since no clear significance threshold for rare genetic variation has been established, some caution is warranted until the findings are further replicated.
PMCID: PMC3392107  PMID: 22556362
7.  TREM2 in neurodegeneration: evidence for association of the p.R47H variant with frontotemporal dementia and Parkinson’s disease 
A rare variant in the Triggering Receptor Expressed on Myeloid cells 2 (TREM2) gene has been reported to be a genetic risk factor for Alzheimer’s disease by two independent groups (Odds ratio between 2.9-4.5). Given the key role of TREM2 in the effective phagocytosis of apoptotic neuronal cells by microglia, we hypothesized that dysfunction of TREM2 may play a more generalized role in neurodegeneration. With this in mind we set out to assess the genetic association of the Alzheimer’s disease-related risk variant in TREM2 (rs75932628, p.R47H) with other related neurodegenerative disorders.
The study included 609 patients with frontotemporal dementia, 765 with amyotrophic lateral sclerosis, 1493 with Parkinson’s disease, 772 with progressive supranuclear palsy, 448 with ischemic stroke and 1957 controls subjects free of neurodegenerative disease. A significant association was observed for the TREM2 p.R47H substitution in susceptibility to frontotemporal dementia (OR = 5.06; p-value = 0.001) and Parkinson’s disease (OR = 2.67; p-value = 0.026), while no evidence of association with risk of amyotrophic lateral sclerosis, progressive supranuclear palsy or ischemic stroke was observed.
Our results suggest that the TREM2 p.R47H substitution is a risk factor for frontotemporal dementia and Parkinson’s disease in addition to Alzheimer’s disease. These findings suggest a more general role for TREM2 dysfunction in neurodegeneration, which could be related to its role in the immune response.
PMCID: PMC3691612  PMID: 23800361
TREM2; Frontotemporal dementia; Parkinson disease; Genetic association
8.  Predicting missing biomarker data in a longitudinal study of Alzheimer disease 
Lo, Raymond Y. | Jagust, William J. | Aisen, Paul | Jack, Clifford R. | Toga, Arthur W. | Beckett, Laurel | Gamst, Anthony | Soares, Holly | C. Green, Robert | Montine, Tom | Thomas, Ronald G. | Donohue, Michael | Walter, Sarah | Dale, Anders | Bernstein, Matthew | Felmlee, Joel | Fox, Nick | Thompson, Paul | Schuff, Norbert | Alexander, Gene | DeCarli, Charles | Bandy, Dan | Chen, Kewei | Morris, John | Lee, Virginia M.-Y. | Korecka, Magdalena | Crawford, Karen | Neu, Scott | Harvey, Danielle | Kornak, John | Saykin, Andrew J. | Foroud, Tatiana M. | Potkin, Steven | Shen, Li | Buckholtz, Neil | Kaye, Jeffrey | Dolen, Sara | Quinn, Joseph | Schneider, Lon | Pawluczyk, Sonia | Spann, Bryan M. | Brewer, James | Vanderswag, Helen | Heidebrink, Judith L. | Lord, Joanne L. | Petersen, Ronald | Johnson, Kris | Doody, Rachelle S. | Villanueva-Meyer, Javier | Chowdhury, Munir | Stern, Yaakov | Honig, Lawrence S. | Bell, Karen L. | Morris, John C. | Mintun, Mark A. | Schneider, Stacy | Marson, Daniel | Griffith, Randall | Clark, David | Grossman, Hillel | Tang, Cheuk | Marzloff, George | Toledo-Morrell, Leylade | Shah, Raj C. | Duara, Ranjan | Varon, Daniel | Roberts, Peggy | Albert, Marilyn S. | Pedroso, Julia | Toroney, Jaimie | Rusinek, Henry | de Leon, Mony J | De Santi, Susan M | Doraiswamy, P. Murali | Petrella, Jeffrey R. | Aiello, Marilyn | Clark, Christopher M. | Pham, Cassie | Nunez, Jessica | Smith, Charles D. | Given, Curtis A. | Hardy, Peter | Lopez, Oscar L. | Oakley, MaryAnn | Simpson, Donna M. | Ismail, M. Saleem | Brand, Connie | Richard, Jennifer | Mulnard, Ruth A. | Thai, Gaby | Mc-Adams-Ortiz, Catherine | Diaz-Arrastia, Ramon | Martin-Cook, Kristen | DeVous, Michael | Levey, Allan I. | Lah, James J. | Cellar, Janet S. | Burns, Jeffrey M. | Anderson, Heather S. | Laubinger, Mary M. | Bartzokis, George | Silverman, Daniel H.S. | Lu, Po H. | Graff-Radford MBBCH, Neill R | Parfitt, Francine | Johnson, Heather | Farlow, Martin | Herring, Scott | Hake, Ann M. | van Dyck, Christopher H. | MacAvoy, Martha G. | Benincasa, Amanda L. | Chertkow, Howard | Bergman, Howard | Hosein, Chris | Black, Sandra | Graham, Simon | Caldwell, Curtis | Hsiung, Ging-Yuek Robin | Feldman, Howard | Assaly, Michele | Kertesz, Andrew | Rogers, John | Trost, Dick | Bernick, Charles | Munic, Donna | Wu, Chuang-Kuo | Johnson, Nancy | Mesulam, Marsel | Sadowsky, Carl | Martinez, Walter | Villena, Teresa | Turner, Scott | Johnson, Kathleen B. | Behan, Kelly E. | Sperling, Reisa A. | Rentz, Dorene M. | Johnson, Keith A. | Rosen, Allyson | Tinklenberg, Jared | Ashford, Wes | Sabbagh, Marwan | Connor, Donald | Jacobson, Sandra | Killiany, Ronald | Norbash, Alexander | Nair, Anil | Obisesan, Thomas O. | Jayam-Trouth, Annapurni | Wang, Paul | Lerner, Alan | Hudson, Leon | Ogrocki, Paula | DeCarli, Charles | Fletcher, Evan | Carmichael, Owen | Kittur, Smita | Mirje, Seema | Borrie, Michael | Lee, T-Y | Bartha, Dr Rob | Johnson, Sterling | Asthana, Sanjay | Carlsson, Cynthia M. | Potkin, Steven G. | Preda, Adrian | Nguyen, Dana | Tariot, Pierre | Fleisher, Adam | Reeder, Stephanie | Bates, Vernice | Capote, Horacio | Rainka, Michelle | Hendin, Barry A. | Scharre, Douglas W. | Kataki, Maria | Zimmerman, Earl A. | Celmins, Dzintra | Brown, Alice D. | Gandy, Sam | Marenberg, Marjorie E. | Rovner, Barry W. | Pearlson, Godfrey | Anderson, Karen | Saykin, Andrew J. | Santulli, Robert B. | Englert, Jessica | Williamson, Jeff D. | Sink, Kaycee M. | Watkins, Franklin | Ott, Brian R. | Wu, Chuang-Kuo | Cohen, Ronald | Salloway, Stephen | Malloy, Paul | Correia, Stephen | Rosen, Howard J. | Miller, Bruce L. | Mintzer, Jacobo
Neurology  2012;78(18):1376-1382.
To investigate predictors of missing data in a longitudinal study of Alzheimer disease (AD).
The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a clinic-based, multicenter, longitudinal study with blood, CSF, PET, and MRI scans repeatedly measured in 229 participants with normal cognition (NC), 397 with mild cognitive impairment (MCI), and 193 with mild AD during 2005–2007. We used univariate and multivariable logistic regression models to examine the associations between baseline demographic/clinical features and loss of biomarker follow-ups in ADNI.
CSF studies tended to recruit and retain patients with MCI with more AD-like features, including lower levels of baseline CSF Aβ42. Depression was the major predictor for MCI dropouts, while family history of AD kept more patients with AD enrolled in PET and MRI studies. Poor cognitive performance was associated with loss of follow-up in most biomarker studies, even among NC participants. The presence of vascular risk factors seemed more critical than cognitive function for predicting dropouts in AD.
The missing data are not missing completely at random in ADNI and likely conditional on certain features in addition to cognitive function. Missing data predictors vary across biomarkers and even MCI and AD groups do not share the same missing data pattern. Understanding the missing data structure may help in the design of future longitudinal studies and clinical trials in AD.
PMCID: PMC3345787  PMID: 22491869
9.  Functional neural correlates of emotional expression processing deficits in behavioural variant frontotemporal dementia 
Frontotemporal dementia (FTD) is a neurodegenerative disorder resulting in social-cognitive deficits partially attributed to abnormalities processing social cues, such as facial expressions. However, to our knowledge, the functional neuroanatomy of deficient social cue processing in individuals with FTD has not been examined. The objective of this study was to delineate the functional abnormalities underlying altered facial expression processing in individuals with FTD using functional magnetic resonance imaging (fMRI).
Patients meeting Neary criteria for behavioural variant FTD (bvFTD) with supportive neuroimaging and 18 age-matched healthy controls completed an implicit facial expression task during fMRI. We conducted volumetric brain morphometry to correct functional imaging data for volume differences.
We included 20 patients with bvFTD and 18 controls in our study. The results demonstrate emotion-specific functional abnormalities in frontal and limbic regions in patients with bvFTD. Patients also showed decreased activity in posterior ventral visual regions, specifically the fusiform cortex, possibly reflecting reduced afferent input from limbic regions. Finally, bvFTD was associated with increased activity in posterior regions, including the inferior parietal cortex.
Autopsy validation of frontotemporal dementia is not yet available for this cohort.
Together, these findings suggest that fMRI combined with tasks targeting social-cognitive deficits is a powerful technique to objectively measure neural systems involved in emotion processing in individuals with bvFTD. As viewing emotional expressions is known to engage many of the same neural systems that are active when experiencing the emotion itself, fMRI during expression processing provides a novel window into the emotions of patients with FTD.
PMCID: PMC3633710  PMID: 23031250
10.  Sensitivity of revised diagnostic criteria for the behavioural variant of frontotemporal dementia 
Brain  2011;134(9):2456-2477.
Based on the recent literature and collective experience, an international consortium developed revised guidelines for the diagnosis of behavioural variant frontotemporal dementia. The validation process retrospectively reviewed clinical records and compared the sensitivity of proposed and earlier criteria in a multi-site sample of patients with pathologically verified frontotemporal lobar degeneration. According to the revised criteria, ‘possible’ behavioural variant frontotemporal dementia requires three of six clinically discriminating features (disinhibition, apathy/inertia, loss of sympathy/empathy, perseverative/compulsive behaviours, hyperorality and dysexecutive neuropsychological profile). ‘Probable’ behavioural variant frontotemporal dementia adds functional disability and characteristic neuroimaging, while behavioural variant frontotemporal dementia ‘with definite frontotemporal lobar degeneration’ requires histopathological confirmation or a pathogenic mutation. Sixteen brain banks contributed cases meeting histopathological criteria for frontotemporal lobar degeneration and a clinical diagnosis of behavioural variant frontotemporal dementia, Alzheimer’s disease, dementia with Lewy bodies or vascular dementia at presentation. Cases with predominant primary progressive aphasia or extra-pyramidal syndromes were excluded. In these autopsy-confirmed cases, an experienced neurologist or psychiatrist ascertained clinical features necessary for making a diagnosis according to previous and proposed criteria at presentation. Of 137 cases where features were available for both proposed and previously established criteria, 118 (86%) met ‘possible’ criteria, and 104 (76%) met criteria for ‘probable’ behavioural variant frontotemporal dementia. In contrast, 72 cases (53%) met previously established criteria for the syndrome (P < 0.001 for comparison with ‘possible’ and ‘probable’ criteria). Patients who failed to meet revised criteria were significantly older and most had atypical presentations with marked memory impairment. In conclusion, the revised criteria for behavioural variant frontotemporal dementia improve diagnostic accuracy compared with previously established criteria in a sample with known frontotemporal lobar degeneration. Greater sensitivity of the proposed criteria may reflect the optimized diagnostic features, less restrictive exclusion features and a flexible structure that accommodates different initial clinical presentations. Future studies will be needed to establish the reliability and specificity of these revised diagnostic guidelines.
PMCID: PMC3170532  PMID: 21810890
behavioural variant frontotemporal dementia; diagnostic criteria; frontotemporal lobar degeneration; FTD; pathology
11.  Ataxin-2 repeat-length variation and neurodegeneration 
Human Molecular Genetics  2011;20(16):3207-3212.
Expanded glutamine repeats of the ataxin-2 (ATXN2) protein cause spinocerebellar ataxia type 2 (SCA2), a rare neurodegenerative disorder. More recent studies have suggested that expanded ATXN2 repeats are a genetic risk factor for amyotrophic lateral sclerosis (ALS) via an RNA-dependent interaction with TDP-43. Given the phenotypic diversity observed in SCA2 patients, we set out to determine the polymorphic nature of the ATXN2 repeat length across a spectrum of neurodegenerative disorders. In this study, we genotyped the ATXN2 repeat in 3919 neurodegenerative disease patients and 4877 healthy controls and performed logistic regression analysis to determine the association of repeat length with the risk of disease. We confirmed the presence of a significantly higher number of expanded ATXN2 repeat carriers in ALS patients compared with healthy controls (OR = 5.57; P= 0.001; repeat length >30 units). Furthermore, we observed significant association of expanded ATXN2 repeats with the development of progressive supranuclear palsy (OR = 5.83; P= 0.004; repeat length >30 units). Although expanded repeat carriers were also identified in frontotemporal lobar degeneration, Alzheimer's and Parkinson's disease patients, these were not significantly more frequent than in controls. Of note, our study identified a number of healthy control individuals who harbor expanded repeat alleles (31–33 units), which suggests caution should be taken when attributing specific disease phenotypes to these repeat lengths. In conclusion, our findings confirm the role of ATXN2 as an important risk factor for ALS and support the hypothesis that expanded ATXN2 repeats may predispose to other neurodegenerative diseases, including progressive supranuclear palsy.
PMCID: PMC3140823  PMID: 21610160
12.  Primary Progressive Aphasias and Their Contribution to the Contemporary Knowledge About the Brain-Language Relationship 
Neuropsychology Review  2011;21(3):271-287.
Primary progressive aphasia (PPA), typically resulting from a neurodegenerative disease such as frontotemporal dementia/Pick Complex or Alzheimer’s disease, is a heterogeneous clinical condition characterized by a progressive loss of specific language functions with initial sparing of other cognitive domains. Based on the constellation of symptoms, PPA has been classified into a nonfluent, semantic, or logopenic variant. This review of the literature aims to characterize the speech and language impairment, cognition, neuroimaging, pathology, genetics, and epidemiology associated with each of these variants. Some therapeutic recommendations, theoretical implications, and directions for future research have been also provided.
PMCID: PMC3158975  PMID: 21809067
Progressive aphasia; Semantic dementia; Frontotemporal dementia; Pick Complex; Alzheimer’s disease
13.  An Exploration of Cognitive Subgroups in Alzheimer's Disease 
Heterogeneity is observed in the patterns of cognition in Alzheimer's disease (AD). Such heterogeneity might suggest the involvement of different aetiological pathways or different host responses to pathology.
627 subjects with mild/moderate AD underwent cognitive assessment with the Mini-Mental Status Exam (MMSE) and the Dementia Rating Scale-2 (DRS-2). Latent class analysis (LCA) was performed on cognition subscale data to identify and characterise cognitive subgroups. Clinical, demographic and genetic factors were explored for association with class membership.
LCA suggested the existence of four subgroups; one group with mild and another with severe global impairment across the cognitive domains, one group with primary impairments in attention and construction, and another group with primary deficits in memory and orientation. Education, disease duration, age, APOE ε4 status, gender, presence of grasp reflex, white matter changes and early or prominent visuospatial impairment were all associated with class membership.
Our results support the existence of heterogeneity in patterns of cognitive impairment in AD. Our observation of classes characterised by predominant deficits in attention/construction and memory respectively deserves further exploration as does the association between membership in the attention/construction class and APOE ε4 negative status.
PMCID: PMC2903844  PMID: 19958568
dementia; latent class analysis; cognition; Mattis Dementia Rating Scale-2; Mini-Mental State Examination; apolipoprotein E
14.  Diagnosis and treatment of dementia: 2. Diagnosis 
Dementia can now be accurately diagnosed through clinical evaluation, cognitive screening, basic laboratory evaluation and structural imaging. A large number of ancillary techniques are also available to aid in diagnosis, but their role in the armamentarium of family physicians remains controversial. In this article, we provide physicians with practical guidance on the diagnosis of dementia based on recommendations from the Third Canadian Consensus Conference on the Diagnosis and Treatment of Dementia, held in March 2006.
We developed evidence-based guidelines using systematic literature searches, with specific criteria for study selection and quality assessment, and a clear and transparent decision-making process. We selected studies published from January 1996 to December 2005 that pertained to key diagnostic issues in dementia. We graded the strength of evidence using the criteria of the Canadian Task Force on Preventive Health Care.
Of the 1591 articles we identified on all aspects of dementia diagnosis, 1095 met our inclusion criteria; 620 were deemed to be of good or fair quality. From a synthesis of the evidence in these studies, we made 32 recommendations related to the diagnosis of dementia. There are clinical criteria for diagnosing most forms of dementia. A standard diagnostic evaluation can be performd by family physicians over multiple visits. It involves a clinical history (from patient and caregiver), a physical examination and brief cognitive testing. A list of core laboratory tests is recommended. Structural imaging with computed tomography or magnetic resonance imaging is recommended in selected cases to rule out treatable causes of dementia or to rule in cerebrovascular disease. There is insufficient evidence to recommend routine functional imaging, measurement of biomarkers or neuropsychologic testing.
The diagnosis of dementia remains clinically integrative based on history, physical examination and brief cognitive testing. A number of core laboratory tests are also recommended. Structural neuroimaging is advised in selected cases. Other diagnostic approaches, including functional neuroimaging, neuropsychological testing and measurement of biomarkers, have shown promise but are not yet recommended for routine use by family physicians.
PMCID: PMC2267847  PMID: 18362376
16.  Aphasia in Clinical Practice 
Canadian Family Physician  1983;29:128-132.
Aphasia is a central language impairment with word finding and comprehension deficit and paraphasias. The highlights of the essential language tests and the classification based on a scorable assessment are presented. The clinical syndromes of Broca's, global, Wernicke, conduction, anomic and transcortical aphasias are detailed with definition, localization, and prognosis. Modality specific disorders associated with aphasic syndromes are discussed. The management of the aphasic patient, consisting of informed support and coordination of available services, is often the responsibility of the family physician.
PMCID: PMC2153532  PMID: 21286589
17.  Low back pain in workmen 
Canadian Medical Association Journal  1977;116(12):1344-1347.
PMCID: PMC1879321  PMID: 20312866
18.  Enlargement of the Sylvian aqueduct: a sequel of head injuries 
A review of pneumoencephalography and clinical data in a large group of patients has shown that severe head injury may be followed by a consistent clinical-radiological syndrome. A prolonged period of unconsciousness is a characteristic initial feature of this syndrome. Clinically there is ataxia and dysarthria and, often, abnormal movements and oculomotor dysfunction. The characteristic radiological feature is an enlargement of the aqueduct of Sylvius. The clinical picture, together with the enlargement of the aqueduct, suggests that loss of neuronal and axonal substance in the midbrain is the probable pathology.
PMCID: PMC494105  PMID: 5049805
19.  Tropical Eosinophilia 
PMCID: PMC1927932  PMID: 14176065

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