Interlocking Finger Test Useful as Screening Tool for Dementia: Study

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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A modified version of the Interlocking Finger Test — a bedside screening done by assessing hand movements — could be useful for detecting dementia in people with Parkinson’s disease, a new study indicates.

“We recommend the use of the modified test version,” the researchers wrote, noting that “scores correlated significantly with global cognition, … memory, [and] attention.”

The study, “A modified version of the interlocking finger test as a bedside screening test for visuospatial deficits and dementia in Parkinson’s disease,” was published in Brain and Behavior.

Many people with Parkinson’s disease experience cognitive problems, such as difficulties with attention or memory. Visuospatial deficits — trouble determining where things are in relation to each other — also are common.

Notably, visuospatial problems are predictive for the eventual development of dementia, or memory and thinking problems that disrupt a person’s daily life.

The Interlocking Finger Test, or ILFT, is a simple bedside test that was developed in the early 2000s to look for certain types of cognitive problems. Simplistically, the test involves an examiner putting his or her hands into a specific shape — for example, interlocking the fingers in a particular manner — and then having the patient try to mimic it. Patients are evaluated on how well they can reproduce the specific shape created by the examiner.

“In this study, we examined whether the ILFT is a suitable bedside screening test for visuospatial functions and/or dementia” in Parkinson’s patients, the researchers wrote. The team was led by a researcher in the department of neurology at the University Oldenburg, in Germany.

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The original ILFT includes four hand gestures, each of which is scored by one point (correct or not). To allow more flexibility in the assessment, the researchers generated a modified version of the Interlocking Finger Test: they added a fifth hand gesture, and each gesture was scored out of three points in total, based on how accurately the patient mimicked the hand movement. The total achievable score for this modified ILFT was 15 points.

The ILFT and its modifications were used to evaluate 47 people with Parkinson’s, diagnosed according to the UK Parkinson’s Disease Society Brain Bank criteria. The patients also underwent a battery of standardized cognitive assessments. Among the patients, about two-thirds were men, the average age was just under 67 years, and the average disease duration was about seven years.

Statistical analyses showed that ILFT scores negatively correlated with age; that is, older patients tended to have poorer scores. ILFT scores also were statistically associated with a number of measures of memory and cognition, but not executive function or language skills. The test scores also were not significantly associated with education, disease duration, the severity of motor symptoms, levodopa treatment, or depression.

“We found significant correlations between ILFT scores and global cognition, visuospatial functions, memory, attention, and age but not between ILFT scores and executive functions, language, education, depression, and disease related variables such as disease duration,” the researchers wrote.

“Remarkably, the ILFT did not reflect motor impairment, given the lack of significant correlations between ILFT and motor scores,” they added.

Based on cognitive scores, the study participants were classified as with or without visuospatial impairments, and with or without dementia. The researchers then assessed the ability of the modified Interlocking Finger Test to differentiate between these groups by calculating the AUC, a statistical measure of how well a given metric (i.e., ILFT score) can tell the difference between two groups. AUC scores range from 0.5 to 1, with higher scores representing a better ability to distinguish.

Using the 15-point modified ILFT, the AUC for predicting visuospatial impairment was 0.82, and the AUC for predicting dementia was 0.88. Based on these findings, as well as the fact that ILFT is a simple test that can be done without complicated equipment, the researchers suggested that this test may be useful to screen for these cognitive problems in Parkinson’s patients.

“We recommend the use of ILFT 15 with cut-off scores of 12.5 for predicting visuospatial deficits or 10.5 for predicting [Parkinson’s]  dementia, respectively,” the team wrote.

“Long-term studies examining if patients with deficits in the ILFT will develop a dementia syndrome in the course of the disease are necessary to verify our results,” they added.