Assessing cognitive dysfunction in Parkinson’s: An online tool to detect visuo-perceptual deficits
2018
BACKGROUND: People with Parkinson’s disease
(PD) who develop visuo-perceptual deficits are at higher
risk of dementia, but we lack tests that detect subtle visuoperceptual
deficits and can be performed by untrained personnel.
Hallucinations are associated with cognitive impairment
and typically involve perception of complex objects.
Changes in object perception may therefore be a sensitive
marker of visuo-perceptual deficits in PD.
Objective: We developed an online platform to test
visuo-perceptual function. We hypothesised that (1)
visuo-perceptual deficits in PD could be detected using
online tests, (2) object perception would be preferentially
affected, and (3) these deficits would be caused
by changes in perception rather than response bias.
METHODS: We assessed 91 people with PD and 275 controls.
Performance was compared using classical frequentist
statistics. We then fitted a hierarchical Bayesian signal
detection theory model to a subset of tasks.
RESULTS: People with PD were worse than controls at
object recognition, showing no deficits in other visuoperceptual
tests. Specifically, they were worse at identifying
skewed images (P <.0001); at detecting hidden
objects (P 5.0039); at identifying objects in peripheral
vision (P <.0001); and at detecting biological motion
(P 5.0065). In contrast, people with PD were not worse
at mental rotation or subjective size perception. Using
signal detection modelling, we found this effect was
driven by change in perceptual sensitivity rather than
response bias.
CONCLUSIONS: Online tests can detect visuo-perceptual defi-
cits in people with PD, with object recognition particularly
affected. Ultimately, visuo-perceptual tests may be developed
to identify at-risk patients for clinical trials to slow PD dementia.
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