09 February 2012
Postuma RB, Bertrand JA,
Montplaisir J, Desjardins C, Vendette M, Rios Romenets, S, Panisset M, Gagnon JF
One of the most devastating nonmotor manifestations of PD is dementia.
There are few established predictors of dementia in PD. In numerous
cross-sectional studies, patients with rapid eye movement (REM) sleep
behavior disorder (RBD) have increased cognitive impairment on
neuropsychological testing, but no prospective studies have assessed
whether RBD can predict Parkinson's dementia.
PD patients who were free
of dementia were enrolled in a prospective follow-up of a previously
published cross-sectional study. All patients had a polysomnogram at
baseline. Over a mean 4-year follow-up, the incidence of dementia was
assessed in those with or without RBD at baseline using regression
analysis, adjusting for age, sex, disease duration, and follow-up
duration.
Of 61 eligible patients, 45 (74%) were assessed and 42 were
included in a full analysis. Twenty-seven patients had baseline RBD, and
15 did not. Four years after the initial evaluation, 48% with RBD
developed dementia, compared to 0% of those without (P-adjusted
= 0.014). All 13 patients who developed dementia had mild cognitive
impairment on baseline examination. Baseline REM sleep atonia loss
predicted development of dementia (% tonic REM = 73.2 ± 26.7 with
dementia, 40.8 ± 34.5 without; P = 0.029). RBD at baseline also
predicted the new development of hallucinations and cognitive
fluctuations.
In this prospective study, RBD was associated with
increased risk of dementia. This indicates that RBD may be a marker of a
relatively diffuse, complex subtype of PD.
