To determine whether there are differences in the age of onset of cognitive impairment and the four core features in a large cohort of patients with clinically diagnosed dementia with Lewy bodies (DLB).

A clinical diagnosis of probable DLB requires progressive cognitive impairment and 2 out of 4 core features: cognitive fluctuations, REM sleep behavior disorder (RBD), visual hallucinations (VH) and parkinsonism. The evolution of these cardinal features with respect to each other during the disease course has not been clearly defined.

A cohort of 315 patients with probable DLB who were seen at least twice at the Mayo Clinic Alzheimer’s Disease Research Center were included in the study. To determine differences in the age of onset of each cardinal feature, we compared Kaplan-Meier (KM) survival curves with the sentinel event representing the age at which each core feature developed. 

Of our sample, 262 (83%) were male and average age at diagnosis was 72.5 years (SD= 7.7). RBD developed the earliest with a median onset age of 65.6 years (95% CI: 64.2 to 67.1) in all patients included.  Estimated age of cognitive symptom onset occurred at a median age of 68.5 years (95% CI: 67.6 to 69.8). Parkinsonism developed in 81% of the sample with a median onset age of 72.1 (95% CI: 70.8 to 73.4) and 71% had fluctuations with a similar median onset age of 73.6 (95% CI: 72.8 to 74.7).  The KM survival curves differed significantly between RBD and cognitive symptoms (p=0.017) as well as parkinsonism and fluctuations (p=0.016). VH were present in 63% emerging at a median age of 79.5 years (95% CI: 78.8 to 81.0). 

Our study confirms that RBD is associated with an earlier age of onset relative to the other core features, followed by cognitive changes, parkinsonism, fluctuations and then VH.