Non-motor predictors of freezing of gait in Parkinson's disease.
Sarah J Banks, Ece Bayram, Guogen Shan and 2 others
PMID 30553992WHAT IT FOUND
Daytime sleepiness and symbol digit test scores predicted freezing four years later.
Anxiety and depression did not predict freezing when motor severity was matched.
Key findings
01At baseline, the freezing group had higher Epworth Sleepiness Scale scores than the no-freezing group.
02SDMT and ESS were significant in the final predictive model, and a one-point increase on each significant scale doubles the likelihood of freezing at year four.
03The final model had an area under the ROC curve of 0.78.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The analysis included only 50 patients with freezing and 50 without freezing. The study was retrospective and used a matched case-control approach from an existing database. Freezing was classified from a patient-reported MDS-UPDRS Part II item converted to present or absent, not from a longer clinician-observed gait assessment. The sample was newly diagnosed and well educated, which may limit generalisation to advanced Parkinson's disease. The cognitive battery did not include some tests, such as trail making and digit span backwards, that other studies have linked to freezing. The follow-up period was four years, so some patients who develop freezing later may have been missed.
Declared interests
The authors reported no conflicts of interest. The article is listed as supported by NIH extramural and non-U.S. government research support, and the data came from the Parkinson's Progression Markers Initiative.
The easy way to misread this
Do not read the finding that a one-point increase in a significant score doubles the likelihood as proof that treating sleepiness or attention prevents freezing. This was a retrospective matched analysis, not a treatment study.