A few simple hand symbols could be useful for screening for dementia in adults with Parkinson’s disease, new research shows.
The interlocking finger test – discussed at length in a 2003 article in the Journal of Neurology, Neurosurgery and Psychiatry – was originally a screening tool for parietal lobe dysfunction, a condition where a person has trouble detecting and understanding their physical environment and objects. The test is intended as a simple bedside screening tool and consists of a patient making four different “figures,” or hand positions, where fingers from both a patient’s hands are intertwined.
Research published earlier this month in Brain and Behavior suggests a modified version of the test could help determine if Parkinson’s patients are also dealing with dementia. The study found the most useful version of the test uses five hand figures instead of the original four.
According to the article, this test could help determine if a patient has dementia and not cognitive impairment related to frontal-striatal network dysfunction, which is also common in Parkinson’s patients. A key difference between the two similar syndromes is what the interlocking finger test was originally intended to test for—visuospatial deficits.
“Distinguishing between these two cognitive syndromes in PD at an early disease stage is important to identify specific cognitive risk profiles, especially with regard to different treatment options,” reads the introduction to the study. “Various tests are available for diagnosing visuospatial deficits, which are highly sensitive to the posterior cortical syndrome; however, upper limb motor impairments, tremor, impaired vision or bedriddenness can be challenging for the neuropsychological diagnostic procedure in PD patients.”
For the new study, researchers evaluated 47 Parkinson’s patients with a cognitive test as well as multiple versions of the interlocking finger test. The version of the test deemed the “best predictor for visuospatial deficits and dementia,” known as ILFT15, involves a slightly modified scoring system, as well as the fifth hand figure.
According to the study’s authors, the interlocking finger test (ILFT) is useful because, in addition to its simplicity, it corrects for a number of variables, including diminished motor skills.
“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 and LEDD,” reads the final section of the study. “Remarkably, the ILFT did not reflect motor impairment, given the lack of significant correlations between ILFT and motor scores. This specific property classified the ILFT as a cognitive rather than a motor task.”