A Comparative Study of Tower of London Scoring Systems and Normative Data

• Published in: Archives of clinical neuropsychology 2017-05, Vol.32 (3), p.328-338
• Main Authors: Michalec, Jiri, Bezdicek, Ondrej, Nikolai, Tomas, Harsa, Pavel, Jech, Robert, Silhan, Petr, Hyza, Martin, Ruzicka, Evzen, Shallice, Tim
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Cognitive Dysfunction - diagnosis; Cognitive Dysfunction - etiology; Data Interpretation, Statistical; Female; Humans; Male; Middle Aged; Neuropsychological Tests - standards; Neuropsychological Tests - statistics & numerical data; Parkinson Disease - complications; Reference Values; Reproducibility of Results; Schizophrenia - complications; Young Adult
• ISSN: 0887-6177; 1873-5843
• DOI: 10.1093/arclin/acw111

Tower of London (ToL) is a planning ability task that includes multiple versions. The original ToL was developed by Shallice together with two scoring systems (ToL-SS). Another two ToL-SS were proposed by Anderson et al. and Krikorian et al. The purpose of this study is to provide normative data for four ToL-SS and explore the effects of demographic variables on ToL performance. Furthermore, we aimed to determine the discriminative validity of these ToL-SS in clinical samples. Four groups were included in the study: a normative sample of healthy adults (HC; n = 298); patients with Parkinson's disease with mild cognitive impairment (PD-MCI; n = 52) and without cognitive impairment (PD-ND; n = 57); and patients with schizophrenia (SCH; n = 28). The effects of demographic variables on ToL-SS were examined in the HC group. Between-groups comparisons of ToL-SS were conducted using regression analysis with dummy codes. All four ToL-SS were not significantly affected by age, whereas the effect of gender and education is not consistent. ToL-SS significantly (p < .05) differentiate HC from PD-MCI and SCH. Cohen's effect size coefficients d range from 0.68 to 1.29. Internal consistency coefficients (Cronbach's α) of ToL-SS range from 0.33 to 0.60. Despite poor to questionable internal consistency of ToL-SS, the discriminative validity and clinical utility for assessing planning deficits in PD-MCI and SCH are high. This study provides normative standards for all four ToL-SS on an adult population for use in clinical practice.