Assessing planning skills and executive functions in the elderly: preliminary normative data for the Tower of London Test

Avaliação das funções executivas e habilidades de planejamento no idoso: referencial normativo preliminar para o Teste da Torre de Londres

LETTERS

Assessing planning skills and executive functions in the elderly: preliminary normative data for the Tower of London Test

Avaliação das funções executivas e habilidades de planejamento no idoso: referencial normativo preliminar para o Teste da Torre de Londres

Jonas Jardim de Paula^I; Fátima Neves^II; Ângela Levy^II; Elaine Nassif^II; Leandro Fernandes Malloy-Diniz^III

^IClinical Neuropsychologist of the Laboratory of Neuropsychological Investigations (LIN), Instituto Nacional de Ciência e Tecnologia em Medicina Molecular (INCTMM), Universidade Federal de Minas Gerais (UFMG), Belo Horizonte MG, Brazil

^IIClinical Psychologists – Private Practice, Belo Horizonte MG, Brazil

^IIIClinical Neuropsychologist of the Laboratory of Neuropsychological Investigations (LIN), Instituto Nacional de Ciência e Tecnologia em Medicina Molecular (INCTMM), Mental Health Department of School of Medicine, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte MG, Brazil

^{Correspondence}

Executive functions are cognitive processes related to planning, execution, and analysis of objective-guided behavior usually associated with fronto-striatal neurocircuitry¹. The planning skills are one of the executive functions associated with the sequencing of steps aiming a nonimmediate objective. A classical measure of planning skills is the Tower of London Test (TOL), developed by Shallice² and adapted by Krikorian³, frequently used in clinical and research settings. Although usually adopted as a measure of executive functions, there are no normative data for the Brazilian elders. The objective of this is study was to develop preliminary normative data for the TOL (Krikorian version).

In the city of Belo Horizonte, in Minas Gerais State, Brazil, 305 elderly participants were invited for this study. All of them answered a semistructured interview aiming the exclusion of neurologic and psychiatric disorders. The inclusion criteria were: Mini-Mental State Exam score above the cutoff for cognitive impairment based on education; score "zero" on the Clinical Dementia Rating; lack of functional impairment on the Katz and Lawton daily life activities indexes; and Geriatric Depression Scale score below the cutoff for depression.

The TOL was applied and corrected based on Krikorian's³ method. The subject receives a wood tower with three pins (large, medium or small) and three balls (red, green or blue), starting from a fixed position he/she must move the balls, one at a time, matching stimulus showed in a card (12 problems), with the minimum moves required (from 2 to 5). If he/she cannot do it or perform with more moves than the minimum required, such person is asked to try it again. Three attempts are given for each problem. The scores are three points for one attempt, two for two attempts, one for three attempts, and none if the problem cannot be solved with three attempts.

Descriptive analysis of the participants was performed and then linear regression analysis was used for assessing the influence of age, education, and gender on test performance. Group comparisons (performed by one-way ANOVA) were used for determining the normative data divisions. Statistical significance was established at 0.05.

The participant's description and test performance are shown in Table. The linear regression model was significant (F=7.00, p<0.001, R²=0.07), showing influence of age (β=-0.19, p=0.001) and education (β=0.18, p<0.001) on test performance, but not of gender (p>0.05). The ANOVA results suggested a normative data division based on age and education, since the proposed age-education groups presented significant differences (F=8.59, p<0.01,η²=0.07).

The TOL is a well-validated classical neuropsychological test for the assessment of planning skills. As other studies suggested, age and education were related to task performance⁴. The development of adequate normative data is essential for cognitive assessment in clinical setting. When a precise characterization of executive/planning performance is necessary, as in the assessment of different conditions like dementia, neuropsychiatry disorders, and mild cognitive impairment, stratified data for sociodemographic factors as age and education allow a more accurate interpretation of test performance and neuropsychological hypothesis testing in the clinical setting⁵.

Received 09 March 2012

Received in final form 03 May 2012

Accepted 10 May 2012

Conflict of interest: There is no conflict of interest to declare.

• 1. Lezak MD, Howieson DB, Loring DW. Neuropsychological Assessment. 4^th ed. New York: Oxford University Press; 2004.
• 2. Shallice T. Specific impairment of planning. Phil Trans R Soc Lond B. 1982;298:199-209.
• 3. Krikorian R, Bartok J, Gay N. Tower of London procedure: a standard method and developmental data. J Clin Exp Neuropsychol 1994;16:840-850.
• 4. Pena-Casanova J, Quiñones-Úbeda S, Quintana-Aparicio M, et al. Spanish Multicenter Normative Studies (NEURONORMA Project): norms for the Stroop Color-Word Interference Test and the Tower of London-Drexel. Arch Clin Neuropsychol 2009;24:413-429.
• 5. de Paula JJ, Moreira L, Nicolato R, et al. The Tower of London Task: different scoring criteria for diagnosing Alzheimer's disease and mild cognitive impairment. Psychol Reports 2012;110:477-488.

Publication Dates

• Publication in this collection
  08 Oct 2012
• Date of issue
  Oct 2012