People with Parkinson’s disease (PD) and their caregivers frequently report cognitive decline as one of their greatest concerns. Commonly described in terms of mild cognitive impairment (PD-MCI) and Parkinson’s disease dementia (PDD), it is estimated that 30 percent of people with Parkinson’s do not develop dementia as part of the disease progression. Research shows that those with PD-MCI are at increased risk for progression to Parkinson’s dementia. Research also shows that the prevalence of dementia increases with a variety of factors, such as age, disease duration and motor severity.
Over the past decade, the International Parkinson and Movement Disorders Society (MDS) created specific criteria to test for PD-related cognitive impairment and dementia, resulting in two types of neuropsychological tests:
- Level I – an abbreviated, short and quick series of tests.
- Level II – a comprehensive, lengthy series of tests shown to successfully predict the increased risk of developing PD-related dementia that considers the effects of age, sex, years of education, depression and the severity of PD movement symptoms.
The challenge, however, is that it is not always possible to conduct the Level II test because of increased costs, time and participants’ inability to cooperate with such a long assessment. Researchers began to wonder, could the Level I test provide similar predictability?
Recently published in Movement Disorders journal, a study titled, “Risk of Parkinson’s Disease Dementia Related to Level I MDS PD-MCI” (Hoogland et al., 2019), sought to evaluate how well the Level I (abbreviated) test might compare to their Level II (comprehensive) test (Hoogland et al., 2017). A sophisticated side-by-side comparison ensued.
A research team analyzed the data of 1,045 people with PD from eight international studies. Key data used included demographics, motor signs, depression, detailed neuropsychological testing and longitudinal follow-up for conversion to Parkinson’s disease dementia (PDD). The five domains evaluated were attention, executive function, memory, visuospatial function and language.
- Having Level I mild cognitive impairment (PD-MCI), increasing age, being male and severity of PD motor signs each independently increased the risk of progression to Parkinson’s disease dementia (PDD).
- Level I mild cognitive impairment in PD classification independently contributes to the increased risk of progressing to dementia.
- Both Level I and Level II mild cognitive impairment in PD classification had similar discriminative ability with respect to the time to Parkinson’s disease dementia. In other words, Level I was as predictive and reliable as Level II.
- The Level II criteria did not show added value compared to Level I.
What Does This Mean?
Called ‘validating an instrument’ in the scientific community, this large, international study w scientifically showed that the Level I test was able to predict the PD-MCI progression to PDD equally well as the Level II test. Being able to make such an accurate prediction quickly, effectively and at reduced cost, early on, has far-reaching implications. Having this predictive level of information in the short-term can help people with PD, caregivers and clinicians improve PD care, understanding and communication.
In the long-term, these findings open new avenues of research to explore, such as the testing the possible positive effects of various lifestyle strategy changes and medications that may slow or halt the progression to dementia.
The Parkinson’s Foundation believes in empowering the Parkinson’s community through education. Learn more about the Parkinson’s and dementia in the below Parkinson’s Foundation resources or by calling our free Helpline at 1-800-4PD-INFO (473-4636).
- Stages of Parkinson’s
- Meet the Researcher: Protein May Predict Dementia Progression in Parkinson’s
- 5 Things You Should Know About the Link Between Parkinson’s and Dementia
Hoogland, J., Boel, J. A., de Bie, R. M. A., Geskus, R. B., Schmand, B. A., Dalrymple-Alford, J. C., . . . Disease, M. D. S. S. G. V. o. M. C. I. i. P. (2017). Mild cognitive impairment as a risk factor for Parkinson's disease dementia. Mov Disord, 32(7), 1056-1065. doi:10.1002/mds.27002
Hoogland, J., Boel, J. A., de Bie, R. M. A., Schmand, B. A., Geskus, R. B., Dalrymple-Alford, J. C., . . . Disease, M. D. S. S. G. V. o. M. C. I. i. P. (2019). Risk of Parkinson's disease dementia related to level I MDS PD-MCI. Mov Disord, 34(3), 430-435. doi:10.1002/mds.27617