Friday 16 November 2018

Do thinking problems develop before Parkinson's?

Many of the blog posts from the PREDICT team have highlighted the fact that Parkinson's affects many more aspects of life than just movement. Whilst the core features are still thought of as slowing down, becoming stiff and developing tremor, problems such as constipation, sleep difficulties and thinking and memory problems are all commonly seen. 

The thinking problems may even be present before diagnosis - testing for specific difficulties could be helpful in the efforts to pick up people at the earliest stages. This research paper used data from a large international study of healthy people who we know are at risk of Parkinson's including people with a sleep disorder strongly related to Parkinson's, people with smell loss and people with genetic mutations associated with Parkinson's.

They found that people with the sleep disorder performed worse on tests of attention and visual function than all the other groups. The groups with smell loss and genetic mutations performed at a similar level across tests and were comparable to people who had already developed Parkinson's. Unfortunately there was no comparison to people without these risk factors, so we can't make any conclusions about whether these groups perform worse than the general population.

I think this finding points to the fact that, just as Parkinson's disease is different in every individual, the route into the disease is also likely to be different. It is also helpful in pointing us towards the specific tests which may be useful in the earliest stages - we have included short tests of attention and memory in the new online PREDICT-PD study www.predictpd.com and I will be very interested to see how our findings compare to these results.

-anna

https://www.ncbi.nlm.nih.gov/pubmed/30125297 


Cognition among individuals along a spectrum of increased risk for Parkinson's disease.

Chahine LM, Urbe L, Caspell-Garcia C, Aarsland D, Alcalay R, Barone P, Burn D, Espay AJ, Hamilton JL, Hawkins KA, Lasch S, Leverenz JB, Litvan I, Richard I, Siderowf A, Coffey CS, Simuni T, Weintraub D; Parkinson’s Progression Markers Initiative. 

Several characteristics associated with increased risk for Parkinson's disease (PD) have been identified, including specific genotypes and various non-motor symptoms. Characterizing non-motor features, such as cognitive abilities, among individuals considered at-risk for PD is essential to improving prediction of future neurodegeneration. METHODS: Participants belonging to the following cohorts of the Parkinson Progression Markers Initiative (PPMI) study were included: de novo PD with dopamine transporter binding deficit (n = 423), idiopathic REM sleep behavior disorder (RBD, n = 39), hyposmia (n = 26) and non-PD mutation carrier (NMC; Leucine-rich repeat kinase 2 (LRRK2) G2019S (n = 88) and glucocerebrosidase (GBA) gene (n = 38) mutations)). Inclusion criteria enriched the RBD and hyposmia cohorts, but not the NMC cohort, with individuals with dopamine transporter binding deficit. Baseline neuropsychological performance was compared, and analyses were adjusted for age, sex, education, and depression. RESULTS: The RBD cohort performed significantly worse than the hyposmia and NMC cohorts on Symbol Digit Modality Test (mean (SD) 32.4 (9.16) vs. 41.8 (9.98), p = 0.002 and vs. 45.2 (10.9), p<0.001) and Judgment of Line Orientation (11.3 (2.36) vs.12.9 (1.87), p = 0.004 and vs. 12.9 (1.87), p<0.001). The RBD cohort also performed worse than the hyposmia cohort on the Montreal Cognitive Assessment (25.5 (4.13) vs. 27.3 (1.71), p = 0.02). Hyposmics did not differ from PD or NMC cohorts on any cognitive test score. CONCLUSION: Among individuals across a spectrum of risk for PD, cognitive function is worse among those with the characteristic most strongly associated with future risk of PD or dementia with Lewy bodies, namely RBD.

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