The closing-in phenomenon in Parkinson's disease

Closing-in (CI) is a peculiar phenomenon consisting in the tendency to copy drawings close to or superimposed on a model. Recent findings showed that CI can be associated with frontal/executive dysfunctions, likely determining a failure in high-level monitoring of attention-action circuits. CI has been often observed in demented patients, but scarce data are available about CI in patients with Parkinson's disease (PD). In the present study, we detected occurrence of CI and investigated the cognitive processes associated to this phenomenon in a large sample of non-demented PD patients.

We retrospectively analysed graphic reproductions in a copying task of 100 non-demented PD patients who had also completed cognitive, behavioural, and motor screening assessment.

CI phenomenon occurred in 50/100 non-demented PD patients (50%; 118/700 drawings). Among these patients, 46/50 patients copied drawings close to the model (near-CI), 2/50 patients superimposed their copy directly on the model (adherent-CI), whereas 2/50 patients showed both near-and adherent-CI. MANOVA showed that non-demented PD patients with CI showed more severe impairment on frontal/executive functions and visuo-constructional abilities than non-demented PD patients without CI. However, the logistic regression model revealed that occurrence of CI was significantly associated to lower scores on frontal/executive tasks only.

CI can be found in a large proportion of non-demented PD patients, and it is related to frontal monitoring defects that could hamper inhibition of action and attention toward a model.