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Informant-Reported Cognitive Decline is Associated with Objective Cognitive Performance in Parkinson’s Disease

Published online by Cambridge University Press:  09 December 2020

Marina Z. Nakhla Open the ORCID record for Marina Z. Nakhla [Opens in a new window] ,
Kelsey A. Holiday ,
J. Vincent Filoteo ,
Zvinka Z. Zlatar ,
Vanessa L. Malcarne ,
Stephanie Lessig ,
Irene Litvan  and
Dawn M. Schiehser
Marina Z. Nakhla
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA SDSU/UC San Diego Joint Doctoral Program in Clinical Psychology, 6363 Alvarado Ct, San Diego, CA, USA
Kelsey A. Holiday
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA SDSU/UC San Diego Joint Doctoral Program in Clinical Psychology, 6363 Alvarado Ct, San Diego, CA, USA
J. Vincent Filoteo
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA92093, USA Department of Neurosciences, Movement Disorder Center, University of California, San Diego, CA, USA
Zvinka Z. Zlatar
Affiliation:
Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA92093, USA
Vanessa L. Malcarne
Affiliation:
SDSU/UC San Diego Joint Doctoral Program in Clinical Psychology, 6363 Alvarado Ct, San Diego, CA, USA Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA92093, USA Department of Psychology, San Diego State University, 5500 Campanile Dr, San Diego, CA92182, USA
Stephanie Lessig
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA Department of Neurosciences, Movement Disorder Center, University of California, San Diego, CA, USA
Irene Litvan
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA Department of Neurosciences, Movement Disorder Center, University of California, San Diego, CA, USA
Dawn M. Schiehser*
Affiliation:
Research Service, VA San Diego Healthcare System, La Jolla, California, 3350 La Jolla Village Dr, San Diego, CA92161, USA Department of Psychiatry, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA92093, USA
*
*Correspondence and reprint requests to: Dawn Schiehser, Ph.D., Research Service, VA San Diego Healthcare System, MC 151-B, La Jolla, CA 92161, USA. Tel.: +1 858 552 8585 ext. 2664; Fax: 858-404-8389. Email: [email protected]
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Abstract

Objective:

The utility of informant-based measures of cognitive decline to accurately describe objective cognitive performance in Parkinson’s disease (PD) without dementia is uncertain. Due to the clinical relevance of this information, the purpose of this study was to examine the relationship between informant-based reports of patient cognitive decline via the Informant Questionnaire of Cognitive Decline in the Elderly (IQCODE) and objective cognition in non-demented PD controlling for cognitive status (i.e., mild cognitive impairment; PD-MCI and normal cognition; PD-NC).

Method:

One-hundred and thirty-nine non-demented PD participants (PD-MCI n = 38; PD-NC n = 101) were administered measures of language, executive function, attention, learning, delayed recall, visuospatial function, mood, and motor function. Each participant identified an informant to complete the IQCODE and a mood questionnaire.

Results:

Greater levels of informant-based responses of patient cognitive decline on the IQCODE were significantly associated with worse objective performance on measures of global cognition, attention, learning, delayed recall, and executive function in the overall sample, above and beyond covariates and cognitive status. However, the IQCODE was not significantly associated with language or visuospatial function.

Conclusions:

Results indicate that informant responses, as measured by the IQCODE, may provide adequate information on a wide range of cognitive abilities in non-demented PD, including those with MCI and normal cognition. Findings have important clinical implications for the utility of the IQCODE in the identification of PD patients in need of further evaluation, monitoring, and treatment.

Keywords

Subjective cognitive declineParkinson’s diseaseNeuropsychologySubjective and objective cognitionInformant reportsCognition
Type
Regular Research
Information
Journal of the International Neuropsychological Society , Volume 27 , Issue 5 , May 2021 , pp. 439 - 449
Copyright
Copyright © INS. Published by Cambridge University Press, 2020

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References

REFERENCES

Amariglio, R.E., Becker, J.A., Carmasin, J., Wadsworth, L.P., Lorius, N., Sullivan, C., … Rentz, D.M. (2012). Subjective cognitive complaints and amyloid burden in cognitively normal older individuals. Neuropsychologia, 50(12), 2880–2886. https://doi.org//10.1016/j.neuropsychologia.2012.08.011 CrossRefGoogle ScholarPubMed
American Psychiatric Association. (2000). Diagnostic and Statistical Manual of Mental Disorders (4th ed.). Washington, DC: American Psychiatric Association.Google Scholar
Barone, P., Aarsland, D., Burn, D., Emre, M., Kulisevsky, J., & Weintraub, D. (2011). Cognitive impairment in nondemented Parkinson’s disease. Movement Disorders, 26(14), 2483–2495. https://doi.org/10.1002/mds.23919 CrossRefGoogle ScholarPubMed
Benton, A.L., Hamsher, K., Varney, N.R., & Spreen, O. (1983). Contributions to Neuropsychological Assessment: A Clinical Manual. New York: Oxford Unniversity Press.Google Scholar
Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences. Hove: Lawrence Erlbaum Associates.Google Scholar
Cooper, R.A., Benge, J., Lantrip, C., & Soileau, M.J. (2017). The everyday cognition scale in Parkinson’s disease. Baylor University Medical Center Proceedings, 30(3), 265–267. https://doi.org/10.1080/08998280.2017.11929611 CrossRefGoogle ScholarPubMed
Copeland, J.N., Lieberman, A., Oravivattanakul, S., & Tröster, A.I. (2016). Accuracy of patient and care partner identification of cognitive impairments in Parkinson’s disease–mild cognitive impairment. Movement Disorders, 31(5), 693–698. https://doi.org/10.1002/mds.26619 CrossRefGoogle ScholarPubMed
Delis, D.C., Kaplan, E., & Kramer, J.H. (2001). Delis-Kaplan Executive Function System® (D-KEFS®): Examiner’s Manual: Flexibility of Thinking, Concept Formation, Problem Solving, Planning, Creativity, Impulse Control, Inhibition. London: Pearson.Google Scholar
Delis, D.C., Kramer, J.H., Kaplan, E., & Ober, B.A. (2000). California Verbal Learning Test-(CVLT-II). San Antonio, TX: Psychological Corporation.Google Scholar
DeVellis, R.F. (2017). Scale Development. Thousand Oaks, CA: Sage.Google Scholar
Ding, Y., Niu, J., Zhang, Y., Liu, W., Zhou, Y., Wei, C., & Liu, Y. (2018). Informant questionnaire on cognitive decline in the elderly (IQCODE) for assessing the severity of dementia in patients with Alzheimer’s disease. BMC Geriatrics, 18(1), 146. https://doi.org/10.1186/s12877-018-0837-9 CrossRefGoogle ScholarPubMed
Emre, M., Aarsland, D., Brown, R., Burn, D.J., Duyckaerts, C., Mizuno, Y., … Dubois, B. (2007). Clinical diagnostic criteria for dementia associated with Parkinson’s disease. Movement Disorders, 22(12), 1689–1707. https://doi.org/10.1002/mds.21507 CrossRefGoogle ScholarPubMed
Erro, R., Santangelo, G., Barone, P., Picillo, M., Amboni, M., Longo, K., … Vitale, C. (2014). Do subjective memory complaints herald the onset of mild cognitive impairment in Parkinson disease? Journal of Geriatric Psychiatry and Neurology, 27(4), 276–281. https://doi.org/10.1177/0891988714532015 CrossRefGoogle ScholarPubMed
Fernandez-Blazquez, M.A., Ávila-Villanueva, M., Maestú, F., & Medina, M. (2016). Specific features of subjective cognitive decline predict faster conversion to mild cognitive impairment. Journal of Alzheimer’s Disease, 52(1), 271–281.CrossRefGoogle ScholarPubMed
Field, A. (2009). Discovering Statistics Using SPSS. (3rd ed.). Thousand Oaks, CA: SAGE Publications.Google Scholar
Goetz, C.G., Poewe, W., Rascol, O., Sampaio, C., Stebbins, G.T., Counsell, C., … Wenning, G.K. (2004). Movement Disorder Society Task Force report on the Hoehn and Yahr staging scale: Status and recommendations the Movement Disorder Society Task Force on rating scales for Parkinson’s disease. Movement Disorders, 19(9), 1020–1028. https://doi.org/10.1002/mds.20213 CrossRefGoogle Scholar
Goldman, J.G., Vernaleo, B.A., Camicioli, R., Dahodwala, N., Dobkin, R.D., Ellis, T., … Simmonds, D. (2018). Cognitive impairment in Parkinson’s disease: A report from a multidisciplinary symposium on unmet needs and future directions to maintain cognitive health. NPJ Parkinson’s Disease, 4(1), 1–11. https://doi.org/10.1038/s41531-018-0055-3 Google ScholarPubMed
Grace, J. & Molloy, P. (2001). Frontal Systems Behavior Scale: Professional Manual. Lutz, FL: Psychological Assessment Resources.Google Scholar
Hong, J.Y., Sunwoo, M.K., Chung, S.J., Ham, J.H., Lee, J.E., Sohn, Y.H., & Lee, P.H. (2014). Subjective cognitive decline predicts future deterioration in cognitively normal patients with Parkinson’s disease. Neurobiology of Aging, 35(7), 1739–1743.CrossRefGoogle ScholarPubMed
Hoogland, J., Boel, J.A., de Bie, R.M.A., Schmand, B.A., Geskus, R.B., Dalrymple-Alford, J.C., … Junque, C. (2019). Risk of Parkinson’s disease dementia related to level I MDS PD-MCI. Movement Disorders, 34(3), 430–435. https://doi.org/10.1002/mds.27617 CrossRefGoogle ScholarPubMed
Hughes, A.J., Ben-Shlomo, Y., Daniel, S.E., & Lees, A.J. (1992). UK Parkinson’s disease society brain bank clinical diagnostic criteria. Journal of Neurology, Neurosurgery, Psychiatry, 55(181), e4.Google Scholar
IBM Corp. (2019). IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp.Google Scholar
Kudlicka, A., Clare, L., & Hindle, J.V. (2011). Executive functions in Parkinson’s disease: Systematic review and meta-analysis. Movement Disorders, 26(13), 2305–2315. https://doi.org/10.1002/mds.23868 CrossRefGoogle ScholarPubMed
Kongs, S.K. (2000). Wisconsin Card Sorting Test: WCST-64. PAR.Google Scholar
Jessen, F. (2014). Subjective and objective cognitive decline at the pre-dementia stage of Alzheimer’s disease. European Archives of Psychiatry and Clinical Neuroscience, 264(1), 3–7. https://doi.org/10.1007/s00406-014-0539-z CrossRefGoogle ScholarPubMed
Jessen, F. & Rodriguez (Née Then) Francisca, S. (2018). Not all, but specific types of cognitive complaints predict decline to MCI. Neurology, 91(4), 153–154. https://doi.org/10.1212/WNL.0000000000005872 CrossRefGoogle ScholarPubMed
Jiménez-Huete, A., Del Barrio, A., Riva, E., Campo, P., Toledano, R., & Franch, O. (2017). Subjective evaluation of mood and cognitive functions in a general neurology clinic: Patients versus informants. Journal of Clinical Neurology, 13(3), 259–264. https://doi.org/10.3988/jcn.2017.13.3.259 CrossRefGoogle Scholar
Jones, J.D., Kurniadi, N.E., Kuhn, T.P., Szymkowicz, S.M., Bunch, J., & Rahmani, E. (2019). Depressive symptoms precede cognitive impairment in de novo Parkinson’s disease patients: Analysis of the PPMI cohort. Neuropsychology. CrossRefGoogle ScholarPubMed
Jorm, A.F. (2004). The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): A review. International Psychogeriatrics, 16(3), 275–293. https://doi.org/10.1017/S1041610204000390 CrossRefGoogle ScholarPubMed
Jorm, A.F., Broe, G.A., Creasey, H., Sulway, M.R., Dent, O., Fairley, M.J., … Tennant, C. (1996). Further data on the validity of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). International Journal of Geriatric Psychiatry, 11(2), 131–139. https://doi.org/10.1002/(SICI)1099-1166(199602)11:2<131::AID-GPS294>3.0.CO;2-5 3.0.CO;2-5>CrossRefGoogle Scholar
Jorm, A.F., Christensen, H., Korten, A.E., Jacomb, P.A., & Henderson, A.S. (2000). Informant ratings of cognitive decline in old age: Validation against change on cognitive tests over 7 to 8 years. Psychological Medicine, 30(4), 981–985. https://doi.org/10.1017/s0033291799002299 CrossRefGoogle ScholarPubMed
Jorm, A.F. & Jacomb, P.A. (1989). The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): Socio-demographic correlates, reliability, validity and some norms. Psychological Medicine, 19(4), 1015–1022. https://doi.org/10.1017/S0033291700005742 CrossRefGoogle ScholarPubMed
Jorm, A.F. & Korten, A.E. (1988). Assessment of cognitive decline in the elderly by informant interview. The British Journal of Psychiatry, 152(2), 209–213. https://doi.org/10.1192/bjp.152.2.209 CrossRefGoogle ScholarPubMed
Jorm, A.F., Scott, R., & Jacomb, P.A. (1989). Assessment of cognitive decline in dementia by informant questionnaire. International Journal of Geriatric Psychiatry, 4(1), 35–39. https://doi.org/10.1002/gps.930040109 CrossRefGoogle Scholar
Kehagia, A.A., Barker, R.A., & Robbins, T.W. (2010). Neuropsychological and clinical heterogeneity of cognitive impairment and dementia in patients with Parkinson’s disease. The Lancet Neurology, 9, 1200–1213. https://doi.org/10.1016/S1474-4422(10)70212-X CrossRefGoogle ScholarPubMed
Kehagia, A.A., Barker, R.A., & Robbins, T.W. (2013). Cognitive impairment in Parkinson’s disease: The dual syndrome hypothesis. Neurodegenerative Diseases, 11(2), 79–92. https://doi.org/10.1159/000341998 CrossRefGoogle ScholarPubMed
Kjeldsen, P.L. & Damholdt, M.F. (2019). Subjective cognitive complaints in patients with Parkinson’s disease. Acta Neurologica Scandinavica, 140(6), 375–389. https://doi.org/10.1111/ane.13158 CrossRefGoogle ScholarPubMed
Koerts, J., van Beilen, M., Leenders, K.L., Brouwer, W.H., Tucha, L., & Tucha, O. (2012). Complaints about impairments in executive functions in Parkinson’s disease: The association with neuropsychological assessment. Parkinsonism & Related Disorders, 18(2), 194–197. https://doi.org/10.1016/j.parkreldis.2011.10.002 CrossRefGoogle ScholarPubMed
Kowal, S.L., Dall, T.M., Chakrabarti, R., Storm, M.V, & Jain, A. (2013). The current and projected economic burden of Parkinson’s disease in the United States. Movement Disorders, 28(3), 311–318. https://doi.org/10.1002/mds.25292 CrossRefGoogle ScholarPubMed
Lawton, M.P. & Brody, E.M. (1969). Assessment of older people: Self-maintaining and instrumental activities of daily living. The Gerontologist, 9(3_Part_1), 179–186. https://doi.org/10.1093/geront/9.3_Part_1.179 CrossRefGoogle ScholarPubMed
Lehrner, J., Kogler, S., Lamm, C., Moser, D., Klug, S., Pusswald, G., … Auff, E. (2015). Awareness of memory deficits in subjective cognitive decline, mild cognitive impairment, Alzheimer’s disease and Parkinson’s disease. International Psychogeriatrics, 27(3), 357–366. https://doi.org/10.1017/S1041610214002245 CrossRefGoogle ScholarPubMed
Leroi, I., Pantula, H., McDonald, K., & Harbishettar, V. (2012). Neuropsychiatric symptoms in Parkinson’s disease with mild cognitive impairment and dementia. Parkinson’s Disease, 2012. https://doi.org/10.1155/2012/308097 Google ScholarPubMed
Litvan, I., Goldman, J.G., Tröster, A.I., Schmand, B.A., Weintraub, D., Petersen, R.C., … Emre, M. (2012). Diagnostic criteria for mild cognitive impairment in Parkinson’s disease: Movement Disorder Society Task Force guidelines. Movement Disorders, 27(3), 349–356. https://doi.org/10.1002/mds.24893 CrossRefGoogle ScholarPubMed
Llebaria, G., Pagonabarraga, J., Kulisevsky, J., García-Sánchez, C., Pascual-Sedano, B., Gironell, A. & Martínez-Corral, M. (2008). Cut-off score of the Mattis Dementia Rating Scale for screening dementia in Parkinson’s disease. Movement Disorders, 23(11), 1546–1550. https://doi.org/10.1002/mds.22173 CrossRefGoogle ScholarPubMed
Mattis, S. (1988). Dementia Rating Scale (DRS) (pp. 1–2). Odessa, FL: Psychological Assessment Resources.Google Scholar
Maxwell, S.E., Delaney, H.D., & Kelley, K. (2018). Designing Experiments and Analyzing Data: A Model Comparison Perspective (3rd ed.). Mahwah, NJ: Lawrence Erlbaum.Google Scholar
Morrell, L., Camic, P.M., & Genis, M. (2019). Factors associated with informant-reported cognitive decline in older adults: A systemised literature review. Dementia, 18(7–8), 2760–2784. https://doi.org/10.1177/1471301218759836 CrossRefGoogle ScholarPubMed
Muslimović, D., Schmand, B., Speelman, J.D., & De Haan, R.J. (2007). Course of cognitive decline in Parkinson’s disease: A meta-analysis. Journal of the International Neuropsychological Society, 13(6), 920–932. https://doi.org/10.10170S1355617707071160 CrossRefGoogle ScholarPubMed
Naismith, S.L., Pereira, M., Shine, J.M., & Lewis, S.J.G. (2011). How well do caregivers detect mild cognitive change in Parkinson’s disease? Movement Disorders, 26(1), 161–164. https://doi.org/10.1002/mds.23331 CrossRefGoogle ScholarPubMed
Olchik, M.R., Ayres, A., Ghisi, M., Schuh, A.F.S., & Rieder, C.R.M. (2016). The impact of cognitive performance on quality of life in individuals with Parkinson’s disease. Dementia & Neuropsychologia, 10(4), 303–309. https://doi.org/10.1590/s1980-5764-2016dn1004008 CrossRefGoogle ScholarPubMed
Papay, K., Mamikonyan, E., Siderowf, A.D., Duda, J.E., Lyons, K.E., Pahwa, R., … Weintraub, D. (2011). Patient versus informant reporting of ICD symptoms in Parkinson’s disease using the QUIP: Validity and variability. Parkinsonism & Related Disorders, 17(3), 153–155. https://doi.org/https://doi.org/10.1016/j.parkreldis.2010.11.015 CrossRefGoogle ScholarPubMed
Pedersen, K.F., Larsen, J.P., Tysnes, O.-B., & Alves, G. (2017). Natural course of mild cognitive impairment in Parkinson disease: A 5-year population-based study. Neurology, 88(8), 767–774. https://doi.org/10.1212/WNL.0000000000003634 CrossRefGoogle ScholarPubMed
Pirogovsky-Turk, E., Schiehser, D.M., Litvan, I., Obtera, K.M., Burke, M.M., Lessig, S.L., … Filoteo, J.V. (2014). The utility of the Mattis Dementia Rating Scale in Parkinson’s disease mild cognitive impairment. Parkinsonism & Related Disorders, 20(6), 627–631. https://doi.org/https://doi.org/10.1016/j.parkreldis.2014.03.010 CrossRefGoogle Scholar
Pirogovsky-Turk, E., Schiehser, D.M., Obtera, K.M., Burke, M.M., Lessig, S.L., Song, D.D., … Filoteo, J.V. (2014). Instrumental activities of daily living are impaired in Parkinson’s disease patients with mild cognitive impairment. Neuropsychology, 28(2) 229–237. https://doi.org/10.1037/neu0000045 CrossRefGoogle Scholar
Pistacchi, M., Gioulis, M., Contin, F., Sanson, F., & Marsala, S.Z. (2015). Cognitive profiles in mild cognitive impairment (MCI) patients associated with Parkinson’s disease and cognitive disorders. Annals of Indian Academy of Neurology, 18(2), 200. https://doi.org/10.4103/0972-2327.150611 CrossRefGoogle ScholarPubMed
Potter, G.G., Plassman, B.L., Burke, J.R., Kabeto, M.U., Langa, K.M., Llewellyn, D.J., … Steffens, D.C. (2009). Cognitive performance and informant reports in the diagnosis of cognitive impairment and dementia in African Americans and whites. Alzheimer’s & Dementia, 5(6), 445–453. https://doi.org/10.1016/j.jalz.2009.04.1234 CrossRefGoogle Scholar
Rabin, L.A., Smart, C.M., Crane, P.K., Amariglio, R.E., Berman, L.M., Boada, M., … Ellis, K.A. (2015). Subjective cognitive decline in older adults: An overview of self-report measures used across 19 international research studies. Journal of Alzheimer’s Disease, 48(s1), S63–S86. https://doi.org/10.3233/JAD-150154 CrossRefGoogle Scholar
Reitan, R.M. & Wolfson, D. (1993). The Halstead-Reitan Neuropsychological Test Battery: Theory and Clinical Interpretation (2nd ed.). Tucson, AZ: Neuropsychology Press.Google Scholar
Saredakis, D., Collins-Praino, L., Gutteridge, D., Stephan, B.C.M., & Keage, H.A.D. (2019). Conversion to MCI and dementia in Parkinson’s disease: A systematic review and meta-analysis. Parkinsonism & Related Disorders. https://doi.org/10.1016/j.parkreldis.2019.04.020 CrossRefGoogle ScholarPubMed
Seltzer, B., Vasterling, J.J., Mathias, C.W., & Brennan, A. (2001). Clinical and neuropsychological correlates of impaired awareness of deficits in Alzheimer disease and Parkinson disease: A comparative study. Cognitive and Behavioral Neurology, 14(2). https://doi.org/10.1016/S0197-4580(00)82779-7 Google ScholarPubMed
Shao, Z., Janse, E., Visser, K., & Meyer, A.S. (2014). What do verbal fluency tasks measure? Predictors of verbal fluency performance in older adults. Frontiers in Psychology, 5, 772. https://doi.org/10.3389/fpsyg.2014.00772 CrossRefGoogle ScholarPubMed
Siciliano, M., De Micco, R., Trojano, L., De Stefano, M., Baiano, C., Passaniti, C., … Tessitore, A. (2017). Cognitive impairment is associated with Hoehn and Yahr stages in early, de novo Parkinson disease patients. Parkinsonism & Related Disorders, 41, 86–91. https://doi.org/10.1016/j.parkreldis.2017.05.020 CrossRefGoogle ScholarPubMed
Stefanova, E., Žiropadja, L., Stojković, T., Stanković, I., Tomić, A., Ječmenica-Lukić, M., … & Kostić, V. (2015). Mild cognitive impairment in early Parkinson’s disease using the Movement Disorder Society Task Force criteria: Cross-sectional study in Hoehn and Yahr stage 1. Dementia and Geriatric Cognitive Disorders, 40, 199–209. https://doi.org/10.1159/000433421 CrossRefGoogle ScholarPubMed
Studart Neto, A. & Nitrini, R. (2016). Subjective cognitive decline: The first clinical manifestation of Alzheimer’s disease? Dementia & Neuropsychologia, 10(3), 170–177. https://doi.org/10.1590/S1980-5764-2016DN1003002 CrossRefGoogle Scholar
Taber, K.S. (2018). The use of Cronbach’s alpha when developing and reporting research instruments in science education. Research in Science Education, 48(6), 1273–1296. https://doi.org/10.1007/s11165-016-9602-2 CrossRefGoogle Scholar
Turner, J. (2020). Graph levodopa equivalent plasma levels. Parkinson’s Measurement. Retrieved from www.parkinsonsmeasurement.org/toolBox/pharmacokinetics.html Google Scholar
Vogel, A., Stokholm, J., Gade, A., Andersen, B.B., Hejl, A.-M., & Waldemar, G. (2004). Awareness of deficits in mild cognitive impairment and Alzheimer’s disease: Do MCI patients have impaired insight? Dementia and Geriatric Cognitive Disorders, 17(3), 181–187. https://doi.org/10.1159/000076354 CrossRefGoogle ScholarPubMed
Wechsler, D. (1997). Wechsler Memory Scale (3rd ed.). San Antonio, TX: The Psychological Corporation.Google Scholar
Werheid, K., Hoppe, C., Thöne, A., Müller, U., Müngersdorf, M., & von Cramon, D.Y. (2002). The Adaptive Digit Ordering Test Clinical application, reliability, and validity of a verbal working memory test. Archives of Clinical Neuropsychology, 17(6), 547–565. https://doi.org/10.1093/arclin/17.6.547 CrossRefGoogle ScholarPubMed
Willis, A.W., Evanoff, B.A., Lian, M., Criswell, S.R., & Racette, B.A. (2010). Geographic and ethnic variation in Parkinson disease: A population-based study of US Medicare beneficiaries. Neuroepidemiology, 34(3), 143–151. https://doi.org/10.1159/000275491 CrossRefGoogle Scholar
Yesavage, J.A., Brink, T.L., Rose, T.L., Lum, O., Huang, V., Adey, M., & Leirer, V.O. (1982). Development and validation of a geriatric depression screening scale: A preliminary report. Journal of Psychiatric Research, 17(1), 37–49. https://doi.org/10.1016/0022-3956(82)90033-4 CrossRefGoogle ScholarPubMed
Zgaljardic, D.J., Borod, J.C., Foldi, N.S., & Mattis, P. (2003). A review of the cognitive and behavioral sequelae of Parkinson’s disease: Relationship to frontostriatal circuitry. Cognitive and Behavioral Neurology, 16(4). https://doi.org/10.1097/00146965-200312000-00001 CrossRefGoogle ScholarPubMed