Intra-individual variability in prodromal Huntington disease and its relationship to genetic burden

Journal of the International Neuropsychological Society

Volumn 21, Issue 1, 2015, Pages 8-21

  Musso, Mandi ^a   Westervelt, Holly James ^a,b   Long, Jeffrey D ^c,d   Morgan, Erin ^e   Woods, Steven Paul ^e   Smith, Megan M ^c   Lu, Wenjing ^c,d   Paulsen, Jane S ^c   Cross, Stephen ^c   Ryan, Patricia ^c   Epping, Eric A ^c   Chiu, Edmond ^f   Preston, Joy ^f   Goh, Anita ^f   Antonopoulos, Stephanie ^f   Loi, Samantha ^f   Chua, Phyllis ^f   Komiti, Angela ^f   Raymond, Lynn ^g   Decolongon, Joji ^g   Fan, Mannie ^g   Coleman, Allison ^g   Ross, Christopher A ^h   Varvaris, Mark ^h   Yoritomo, Nadine ^h   Mallonee, William M ⁱ   Suter, Greg ⁱ   Samii, Ali ^j   Macaraeg, Alma ^j   Jones, Randi ^k   Wood Siverio, Cathy ^k   Factor, Stewart A ^k   Barker, Roger A ^l   Mason, Sarah ^l   Guzman, Natalie Valle ^l   McCusker, Elizabeth ^m   Griffith, Jane ^m   Loy, Clement ^m   Gunn, David ^m   Orth, Michael ⁿ   Süßmuth, Sigurd ⁿ   Barth, Katrin ⁿ   Trautmann, Sonja ⁿ   Schwenk, Daniela ⁿ   Eschenbach, Carolin ⁿ   Quaid, Kimberly ^o   Wesson, Melissa ^o   Wojcieszek, Joanne ^o   Guttman, Mark ^p   Sheinberg, Alanna ^p   Karmalkar, Irita ^p   Perlman, Susan ^q   Clemente, Brian ^q   Geschwind, Michael D ^r   Sha, Sharon ^r   Satris, Gabriela ^r   Warner, Tom ^s   Burrows, Maggie ^s   Rosser, Anne ^t   Price, Kathy ^t   Hunt, Sarah ^t   Marshall, Frederick ^u   Chesire, Amy ^u   Wodarski, Mary ^u   Hickey, Charlyne ^u   Panegyres, Peter ^v   Lee, Joseph ^v   Tedesco, Maria ^v   Maxwell, Brenton ^v   Perlmutter, Joel ^w   Barton, Stacey ^w   Smith, Shineeka ^w   Miedzybrodzka, Zosia ^x   Rae, Daniela ^x   D'Alessandro, Mariella ^x   Craufurd, David ^y   Bek, Judith ^y   Howard, Elizabeth ^y   Mazzoni, Pietro ^z   Marder, Karen ^z   Wasserman, Paula ^z   Kumar, Rajeev ^aa   Erickson, Diane ^aa   Nickels, Breanna ^aa   Wheelock, Vicki ^ab   Kjer, Lisa ^ab   Martin, Amanda ^ab   Farias, Sarah ^ab   Suchowersky, Oksana ^ac   Martin, Wayne ^ac   King, Pamela ^ac   Wieler, Marguerite ^ac   Sran, Satwinder ^ac   Ahmed, Anwar ^ad   Rao, Stephen ^ad   Reece, Christine ^ad   Bura, Alex ^ad   Mourany, Lyla ^ad   Montross, Kelsey ^ah   Vonsattell, Jean Paul ^z   Moskowitz, Carol ^z   Vik, Stacie ^c   Harrington, Deborah ^e   Hershey, Tamara ^w   Moser, David J ^c   Williams, Janet ^c   Downing, Nancy ^c   Johnson, Hans J ^c   Aylward, Elizabeth ^ae   Magnotta, Vincent A ^c   Kim, Ji In ^c   Mills, James A ^c   Zhang, Ying ^c   Liu, Dawei ^c   Lourens, Spencer ^c   Erwin, Cheryl ^af   Nance, Martha ^ag   Bockholt, H Jeremy ^c   Wyse, Ryan ^c   more..

^a BROWN UNIVERSITY   (United States)

^b RHODE ISLAND HOSPITAL   (United States)

^c UNIVERSITY OF IOWA   (United States)

^d UNIVERSITY OF IOWA   (United States)

^e UNIVERSITY OF CALIFORNIA   (United States)

^f UNIVERSITY OF MELBOURNE   (Australia)

^g UNIVERSITY OF BRITISH COLUMBIA   (Canada)

^h JOHNS HOPKINS UNIVERSITY   (United States)

ⁱ Hereditary Neurological Disease Centre   (United States)

^j UNIVERSITY OF WASHINGTON   (United States)

^k EMORY UNIVERSITY SCHOOL OF MEDICINE   (United States)

^l UNIVERSITY OF CAMBRIDGE   (United Kingdom)

^m WESTMEAD HOSPITAL   (Australia)

ⁿ UNIVERSITY OF ULM   (Germany)

^o INDIANA UNIVERSITY   (United States)

^p UNIVERSITY OF TORONTO   (Canada)

^q UNIVERSITY OF CALIFORNIA   (United States)

^r UNIVERSITY OF CALIFORNIA   (United States)

^s NATIONAL HOSPITAL FOR NEUROLOGY AND NEUROSURGERY   (United Kingdom)

^t CARDIFF UNIVERSITY   (United Kingdom)

^u UNIVERSITY OF ROCHESTER   (United States)

^v Graylands Selby Lemnos and Special Care Health Services   (Australia)

^w WASHINGTON UNIVERSITY   (United States)

^x Clinical Genetics Centre   (United Kingdom)

^y UNIVERSITY OF MANCHESTER   (United Kingdom)

^z Colorado Neurological Institute ^*  (United States)

^aa University of California Davis ^*  (United States)

^ab UNIVERSITY OF CALIFORNIA   (United States)

^ac UNIVERSITY OF ALBERTA   (Canada)

^ad LERNER RESEARCH INSTITUTE   (United States)

^ae SEATTLE CHILDREN S RESEARCH INSTITUTE   (United States)

^af TEXAS TECH UNIVERSITY HEALTH SCIENCES CENTER   (United States)

^ag UNIVERSITY OF MINNESOTA   (United States)

^ah NONE

more..

Author keywords

Adult; Attention; Cognition disorders diagnosis; Cognition disorders genetics; Executive function; Huntington disease; Intra individual variability; Neuropsychological tests; Prodromal symptoms

Indexed keywords

ADULT; ANALYSIS OF VARIANCE; COGNITION DISORDERS; DECISION MAKING; DISEASE COURSE; FEMALE; GENETICS; HUMAN; HUNTINGTON CHOREA; INDIVIDUALITY; MALE; MIDDLE AGED; NEUROLOGIC EXAMINATION; NEUROPSYCHOLOGICAL TEST; PATHOPHYSIOLOGY; PHYSIOLOGY; PRODROMAL SYMPTOM; REACTION TIME; SELF CONCEPT; TIME PERCEPTION; TRINUCLEOTIDE REPEAT;

ADULT; ANALYSIS OF VARIANCE; CHOICE BEHAVIOR; COGNITION DISORDERS; DISEASE PROGRESSION; FEMALE; HUMANS; HUNTINGTON DISEASE; INDIVIDUALITY; MALE; MIDDLE AGED; NEUROLOGIC EXAMINATION; NEUROPSYCHOLOGICAL TESTS; PRODROMAL SYMPTOMS; REACTION TIME; SELF CONCEPT; TIME PERCEPTION; TRINUCLEOTIDE REPEAT EXPANSION;

EID: 84928013791     PISSN: 13556177     EISSN: 14697661     Source Type: Journal    
DOI: 10.1017/S1355617714001076     Document Type: Article

References (64)

1. Aylward, E.H., Liu, D., Nopoulos, P.C., Ross, C.A., Pierson, R.K., Mills, J.A., ... the PREDICT-HD Inestigators and Coordinators of the Huntington Study Group (2012). Striatal volume contributes to the prediction of onset of Huntington disease in incident cases. Biological Psychiatry, 71, 822-828. doi:10.1016/ j.biopsych.2011.07.030
2. Ballard, C., O'Brien, J., Gray, A., Cormack, F., Ayre, G., Rowan, E.,... Tovee, M. (2001). Attention and fluctuating attention in patients with dementia with Lewy bodies and Alzheimer disease. Archives of Neurology, 58(6), 977. doi:10.1001/ archneur.58.6.977
3. Beglinger, L.J., O'Rourke, J.J., Wang, C., Langbehn, D.R., Duff, K., Paulsen, J.S., & Huntington Study Group Investigators. (2010). Earliest functional declines in Huntington disease. Psychiatry Research, 178, 414-418. doi:10.1016/j.psychres.2010.04.030
4. Bellgrove, M.A., Hester, R., & Garavan, H. (2004). The functional neuroanatomical correlates of response variability: Evidence from a response inhibition task. Neuropsychologia, 42, 1910-1916. doi:10.1016/j.neuropsychologia.2004.05.007
5. Benton, A.L., Hamsher, K., Varney, N., & Spreen, O. (1983). Contributions to neuropsychological assessment: A clinical manual. New York: Oxford University Press.
6. Brandt, J., & Benedict, R.H.B. (2001). Hopkins verbal learning test-revised. Lutz: Psychological Assessment Resources.
7. Brandt, J., & Butters, N. (1986). The neuropsychology of Huntington's disease. Trends in Neurosciences, 9, 118-120. doi:10.1016/0166-2236(86)90039-1
8. Bunce, D., Anstey, K.J., Christensen, H., Dear, K., Wen, W., & Sachdev, P. (2007). White matter hyperintensities and withinperson variability in community-dwelling adults aged 60-64 years. Neuropsychologia, 45(9), 2009-2015. doi:10.1016/j. neuropsychologia.2007.02.006
9. Castellanos, F.X., Sonuga-Barke, E.J., Scheres, A., Di Martino, A., Hyde, C., & Walters, J.R. (2005). Varieties of attention-deficit/ hyperactivity disorder-related intra-individual variability. Biological Psychiatry, 57, 1416-1423. doi:10.1016/j.biopsych.2004. 12.005
10. Cherbuin, N., Sachdev, P., & Anstey, K. (2010). Neuropsychological predictors of transition from healthy cognitive aging to mild cognitive impairment: The PATH through life study. American Journal of Geriatric Psychiatry, 18, 723-733. doi:10.1097/ JGP.0b013e3181cdecf1
11. Christensen, H., Mackinnon, A.J., Korten, A.E., Jorm, A.F., Henderson, A.S., & Jacomb, P. (1999). Dispersion in cognitive abilities as a function of age: A longitudinal study of an elderly community sample. Aging, Neuropsychology, and Cognition, 6, 214-228. doi:10.1076/anec.6.3.214.779
12. Cole, V.T., Weinberger, D.R., & Dickinson, D. (2011). Intra-individual variability across neuropsychological tasks in schizophrenia: A comparison of patients, siblings, and healthy controls. Schizophrenia Research, 129, 91-93. doi:10.1016/j. schres.2011.03.007
13. Duchek, J.M., Balota, D.A., Tse, C.-S., Holtzman, D.M., Fagan, A. M., & Goate, A.M. (2009). The utility of intraindividual variability in selective attention tasks as an early marker for Alzheimer's Disease. Neuropsychology, 23, 746-758. doi:10.1037/ a0016583
14. Duff, K., Paulsen, J.S., Mills, J., Beglinger, L.J., Moser, D.J., Smith, M.M.,...the PREDICT-HD Inestigators and Coordinators of the Huntington Study Group (2010). Mild cognitive impairment in prediagnosed Huntington disease. Neurology, 75, 500-507. doi:10.1212/WNL.0b013e3181eccfa2
15. Ekman, P., & Friesen, W.V. (1976). Measuring facial movement. Environmental Psychology and Nonverbal Behavior, 1, 56-75. doi:10.1007/BF01115465
16. Frazier-Wood, A.C., Bralten, J., Arias-Vasquez, A., Luman, M., Ooterlaan, J., Sergeant, J.,... Rommelse, N.N. (2011). Neuropsychological intra-individual variability explains unique genetic variance of ADHD and shows suggestive linkage to chromosomes 12, 13, and 17. American Journal of Medical Genetics Part B, 159B, 131-140. doi:10.1002/ajmg.b.32018
17. Georgiou, N., Bradshaw, J.L., Phillips, J.G., Chiu, E.,&Bradshaw, J.A. (1995). Reliance upon advance information and movement sequencing in Huntington's disease. Movement Disorders, 10, 472-481. doi:10.1002/mds.870100412
18. Harrington, D.L., Smith, M.M., Zhang, Y., Carlozzi, N.E., Paulsen, J.S., & the PREDICT-HD Inestigators and Coordinators of the Huntington Study Group. (2012). Cognitive domains that predict time to diagnosis in prodromal Huntington disease. Journal of Neurology, Neurosurgery, and Psychiatry, 83, 612-619. doi:10.1136/jnnp-2011-301732
19. Hilborn, J.V., Strauss, E., Hultsch, D.F., & Hunter, M.A. (2009). Intraindividual variability across cognitive domains: Investigation of dispersion levels and performance profiles in older adults. Journal of Clinical and Experimental Neuropsychology, 31, 412-424. doi:10.1080/13803390802232659
20. Hinton, S.C., Paulsen, J.S., Hoffmann, R.G., Reynolds, N.C., Zimbelman, J.L., Rao, S.M. (2007). Motor timing variability increases in preclinical Huntington's disease patients as estimated onset of motor symptoms approaches. Journal of the International Neuropsychological Society, 13, 539-543. doi:10.1017/ S1355617707070671
21. Holtzer, R., Verghese, J., Wang, C., Hall, C., & Lipton, R.B. (2008). Within-person across-neuropsychological test variability and incident dementia. JAMA, 300, 823-830. doi:10.1001/jama.300.7.823
22. Hultsch, D.F., MacDonald, S.W., Hunter, M.A., Levy-Bencheton, J., & Strauss, E. (2000). Intraindividual variability in cognitive performance in older adults: comparison of adults with mild dementia, adults with arthritis, and healthy adults. Neuropsychology, 14, 588-598.
23. Hultsch, D.F., MacDonald, S.W., & Dixon, R.A. (2002). Variability in reaction time performance of younger and older adults. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 57, P101-P115. doi:10.1093/geronb/57.2.P101
24. Huntington Study Group. (1996). Unified Huntington's Disease Rating Scale: Reliability and consistency. Movement Disorders, 11, 136-142. doi:10.1002/mds.870110204
25. Johnson, S.A., Stout, J.C., Solomon, A.C., Langbehn, D.R., Aylward, E.H., Cruce, C.B., & Paulsen, J.S. (2007). Beyond disgust: Impaired recognition of negative emotions prior to diagnosis in Huntington's disease. Brain, 130, 1732-1744. doi:10.1093/brain/awm107
26. Kaiser, S., Roth, A., Rentrop, M., Friederich, H.-C., Bender, S., & Weisbrod, M. (2008). Intra-individual reaction time variability in schizophrenia, depression, and borderline personality disorder. Brain and Cognition, 66, 73-82. doi:10.1016/j.bandc.2007.05.007
27. Kieburtz, K., Penney, J.B., Como, P., Ranen, N., Shoulson, I., Feigin, A., ... Kremer, B. (1996). Unified Huntington's disease rating scale: Reliability and consistency. Movement Disorders, 11, 136-142. doi:10.1002/mds.870110204
28. Kirkwood, S.C., Siemers, E., Stout, J.C., Hodes, M.E., Conneally, P.M., Christian, J.C., & Foroud, T. (1999). Longitudinal cognitive and motor changes among presymptomatic Huntington disease gene carriers. Archives of Neurology, 56, 563-568. doi:10.1001/ archneur.56.5.563
29. Klein, C., Wendling, K., Huettner, P., Ruder, H., & Peper, M. (2006). Intra-subject variability in attention-deficits hyperactivity disorder. Biological Psychiatry, 60, 1088-1097. doi:10.1016/j. biopsych.2006.04.003
30. Lee, J.M., Ramos, E.M., Lee, J.H., Gillis, T., Mysore, J.S., Hayden, M.R., ... Gusella, J.F. (2012). CAG repeat expansion in Huntington disease determines age at onset in a fully dominant fashion. Neurology, 78, 690-695. doi:10.1212/WNL.0b013e 318249f683
31. Long, J.D., Paulsen, J.S., Marder, K., Zhang, Y., Kim, J.-I., Mills, J.A., & the Researchers of the PREDICT-HD Huntington's Study Group (2014). Tracking motor impairments in the progression of Huntington's disease. Movement Disorders, 29, 311-319. doi:10.1002 /mds.25657
32. MacDonald, M.E., Ambrose, C.M., Duyao, M.P., Myers, R.H., Lin, C., Srinidhi, L., ... Gusella, J.F. (1993). A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington's disease chromosomes. Cell, 72, 971-983. doi:10.1016/0092-8674 (93)90585-E
33. MacDonald, S.W., Backman, L., & Li, S.-C. (2009). Neural underpinnings of within-person variability in cognitive functioning. Psychology and Aging, 24, 792-808. doi:10.1037/ a0017798
34. Morgan, E.E., Woods, S.P., Grant, I., & The H.I.V. Neurobehavioral Research Program (HNRP) Group. (2012a). Intraindividual neurocognitive variability confers risk of dependence in activities of daily living among HIV-seropositive individuals without HIV-Assoicated Neurocogntive Disorders. Archives of Clinical Neuropsychology, 27, 293-303. doi:10.1093/arclin/acs003
35. Morgan, E.E., Woods, S.P., Rooney, A., Perry, W., Grant, I., & Letendre, S.L., the Neurobehavioral Research Program (HNRP) Group. (2012b). Intra-Individual Variability across neurocognitive domains in chronic Hepatitis C infection: Elevated dispersion is associated with serostatus and unemployment risk. The Clinical Neuropsychologist, 26, 654-674. doi:10.1080/13854046.2012. 680912
36. Murtha, S., Cismaru, R., Waechter, R., & Chertkow, H. (2002). Increased variability accompanies frontal lobe damage in dementia. Journal of the International Neuropsychological Society, 8, 360-372. doi:10.1017.S1355617701020173
37. Papp, K.V., Snyder, P.J., Mills, J.A., Duff, K., Westervelt, H.J., Long, J.D., ... Paulsen, J.S. (2013). Measuring executive dysfunction longitudinally and in relation to genetic burden, brain volumetrics, and depression in prodromal Huntington disease. Archives of Clinical Neuropsychology, 28, 156-168. doi:10.1093/arclin/acs105
38. Paulsen, J.S. (2001). PREDICT-HD: Markers indentifying individuals at risk for Huntington disease [Abstract]. Archives of Neurology, 58, 1317.
39. Paulsen, J.S., Langbehn, D.R., Stout, J.C., Aylward, E., Ross, C.A., Nance, M.,... The PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2008). Detection of Huntington's disease decades before diagnosis: The Predict-HD study. Journal of Neurology, Neurosurgery, and Psychiatry, 79, 874-880. doi:10.1136/jnnp.2007.128728
40. Paulsen, J.S., Nopoulos, P.C., Aylward, E., Ross, C.A., Johnson, H., Magnotta, V.A., ... PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2010a). Striatal and white mater predictors of estimated diagnosis for Huntington disease. Brain Research Bulletin, 82, 201-207. doi:10.1016/j. brainresbull.2010.04.003
41. Paulsen, J.S., Smith, M.M., Long, J.S., & the PREDICT HD investigators and coordinators of the Huntington Study Group. (2013). Cognitive decline in prodromal Huntington Disease: implications for clinical trials. Journal of Neurology, Neurosurgery, and Psychiatry, 84, 1233-1239. doi:10.1136/jnnp-2013-305114
42. Paulsen, J.S., Wang, C., Duff, K., Barker, R., Nance, M., Beglinger, L., ... van Kammen, D.P. (2010b). Challenges assessing clinical endpoints in early Huntington disease. Movement Disorders, 25, 2595-2603. doi:10.1002/mds.23337
43. Paulsen, J.S., Zhao, H., Stout, J.C., Brinkman, R.R., Guttman, M., Ross, C.A., ... The PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2001). Clinical markers of early disease in persons near onset of Huntington's disease. Neurology, 57, 658-662. doi:10.1212/WNL.57.4.658
44. Paulsen, J.S., Zimbelman, J.L., Hinton, S.C., Langbehn, D.R., Leveroni, C.L., Benjamin, M.L., & Rao, S.M. (2004). fMRI biomarker of early neuronal dysfunction in presymptomatic Huntington's disease. AJNR American Journal of Neuroradiology, 25, 1715-1721.
45. Penney, J.B., Young, A.B., Shoulson, I., Starosta-Rubenstein, S., Snodgrass, S.R., Sanchez-Ramos, J., ... Wexler, N.S. (1990). Huntington's disease in Venezuela: 7 years of follow-up on symptomatic and asymptomatic individuals. Movement Disorders, 5, 93-99.
46. Pirogovsky, E., Gilbert, P.E., Jacobson, M., Peavy, G., Wetter, S., Goldstein, J., ... Murphy, C. (2007). Impairments in source memory for olfactory and visual stimuli in preclinical and clinical stages of Huntington's disease. Journal of Clinical and Experimental Neuropsychology, 29, 395-404. doi:10.1080/138033 90600726829
47. Reitan, R.M. (1958). Validity of the Trail Making Test as an indicator of organic brain damage. Perceptual and Motor Skills, 8, 271-276. doi:10.2466/PMS.8.7.271-276
48. Rentrop, M., Rodewald, K., Roth, A., Simon, J., Walther, S., Fiedler, P., ... Kaiser, S. (2010). Intra-individual variability in high-functioning patients with schizophrenia. Psychiatry Research, 178, 27-32. doi:10.1016/j.psychres.2010.04.009
49. Rowe, K.C., Paulsen, J.S., Langbehn, D.R., Duff, K., Beglinger, L.J., Wang, C., ... Moser, D.J. (2010). Self-paced timing detects and tracks change in prodromal Huntington disease. Neuropsychology, 24, 435, doi:10.1037/a0018905
50. Saint-Cyr, J.A., Taylor, A.E., & Lang, A.E. (1988). Procedural learning and neostriatal dysfunction in man. Brain, 111, 941-959. doi:10.1093/brain/111.4.941
51. Scahill, R.I., Hobbs, N.Z., Say, M.J., Bechtel, N., Henley, S.M., Hyare, H., ... The TRACK-HD Investigators (2013). Clinical impairment in premanifest and early Huntington's disease is associated with regionally specific atrophy. Human Brain Mapping, 34, 519-529. doi:10.1002/hbm.21449
52. Smith, A. (1991). Symbol Digit Modalities Test. Los Angeles: Western Psychological Services.
53. Smith, M.M., Mills, J.A., Epping, E.A., Westervelt, H.J.,&Paulsen, J.S. (2012). Depressive symptom severity is related to poorer cognitive performance in prodromal Huntington disease. Neuropsychology, 26, 664-669. doi:10.1037/a0029218
54. Stout, J.C., Jones, R., Labuschagne, I., O'Regan, A.M., Say, M.J., Dumas, E.M., ... the PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2012). Evaluation of longitudinal 12 and 24 month cognitive outcomes in premanifest and early Huntington's disease. Journal of Neurology, Neurosurgery, and Psychiatry, 83, 687-694. doi:10.1136/jnnp-2011-301940
55. Stout, J.C., Paulsen, J.S., Queller, S., Solomon, A.C., Whitlock, K.B., Campbell, J.C., ... the PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2011). Neurocognitive sings in prodromal Huntington disease. Neuropsychology, 25, 1-14. doi:10.1037/a0020937
56. Stroop, J.R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology: General, 18(6), 643-662. doi:10.1037/0096-3445.121.1.15
57. Stuss, D.T., Murphy, K.J., & Binns, M.A. (1999). The frontal lobes and performance variability: Evidence from reaction time. Journal of the International Neuropsychological Society, 5, 123.
58. Stuss, D.T., Murphy, K.J., Binns, M.A., & Alexander, M.P. (2003). Staying on the job: The frontal lobes control individual performance variability. Brain, 126, 2363-2380. doi:10.1093/ brain/awg237
59. Stuss, D.T., Stethem, L.L., Hugenholtz, H., Picton, T., Pivik, J., & Richard, M.T. (1989). Reaction time after head injury: Fatigue, divided and focused attention, and consistency of performance. Journal of Neurology, Neurosurgery, and Psychiatry, 52, 742-748. doi:10.1136/jnnp.52.6.742
60. Warner, J.P., Barron, L.H., & Brock, D.J. (1993). A new plymerase chain reaction (PCR) assay for trinucleotide repeat that is unstable and expanded on Huntington's disease chromosomes. Molecular and Cellular Probes, 7, 235-239. doi:10.1006/mcpr.1993.1034r
61. Willingham, D.B., Nissen, M.J., & Bullemer, P. (1989). On the development of procedural knowledge. Journal of Experimental Psychology. Learning, Memory, and Cognition, 15, 1047-1060. doi:10.1037/0278-7393.15.6.1047
62. Wechsler, D. (1997). Wechsler Adult Intelligence Scale. 3rd ed. San Antonio: The Psychological Corporation.
63. Zakzanis, K.K. (1998). The Subcortical Dementia of Huntington's Disease. Journal of Clinical and Experimental Neuropsychology, 20, 565-578. doi:10.1076/jcen.20.4.565.1468
64. Zhang, Y., Long, J.D., Mills, J.A., Warner, J.H., Lu, W., Paulsen, J.S., ...the PREDICT-HD Investigators and Coordinators of the Huntington Study Group (2011). Indexing disease progression at study entry with individuals at-risk for Huntington disease. American Journal of Medical Genetics Part B, 156, 751-763. doi:10.1002/ajmg.b.31232