The Tower of London test: A test for dementia

Abstract

Objectives: The Tower of London (ToL) is a problem-solving task, which is a valuable tool for the neuropsychological examination of a patient with a possible cognitive decline. The aim of the present study was to evaluate the ToL in comparison to the Mini Mental State Examination (MMSE) in a group of older people with or without dementia. Method: Seventy outpatients of both sexes, 30 with low-moderate dementia and 40 with apparently normal cognition were evaluated with the MMSE and the ToL task in the same day. The ToL score was calculated according to the Krikorian method and also the execution time was measured. The differences between groups were assessed with the unpaired t-test, and the relationship between two parameters was assessed with the analysis of the coefficient of linear regression. The results were adjusted for age and education. Results: The evaluation of cognitive impairment by MMSE showed a significant difference in the two groups (p < 0.001). The mean scores (p < 0.001) and execution times (p < 0.05) of the ToL, resulted significantly lower in the patients affected by dementia. However, seven participants with dementia had a normal score in the ToL test, indicating that the executive neuropsychological tasks could be preserved notwithstanding the cognitive decline and nine participants with normal MMSE obtained a low ToL score, suggestive of the higher sensibility of the ToL for the executive task that reveals an unknown cognitive deficit. Conclusion: The correlation between MMSE and ToL is good, but ToL test provides complementary information to the MMSE and vice versa.