Functional imaging of working memory in Parkinson's disease: compensations and deficits.
OBJECTIVE
Over and above typical motor alterations, executive and working memory (WM) impairment can also occur in early idiopathic Parkinson's disease (PD). We aimed to investigate the compensatory neural processes involved in WM performance, as well as the networks involved in the long-term memory transfer from short-term stores in PD.


METHODS
Relative cerebral blood flow (rCBF) was mapped with H2O(15)-PET in eight treated nondemented PD patients while performing a WM verbal double-task (Brown-Peterson paradigm) using both short (6-second) and long (18-second) delays.


RESULTS
As compared to nine age-matched healthy subjects, performance of the PD group was only slightly reduced on the short-delay but markedly impaired on the long-delay task. Underlying the relatively preserved short-delay performance, the PD group exhibited overactivation of prefrontal and parietal areas involved in attention-demanding processes, suggestive of efficient compensatory processes. Further supporting this, significant positive correlations were found between short-delay performance and rCBF in the bilateral inferior parietal cortex. In contrast, the lack of overactivation with the long-delay task together with posterior cingulate hypoactivation would support the idea of functional disconnection impairing transfer of information from prefrontal onto (para)limbic areas. These findings suggest novel areas of investigation into early cognitive impairments in PD.
Marié
Rose-Marie
RM
University of Caen, University Team Executive and Attentional Processes and UPRES-EA 3917, Caen, France.
Lozza
Catherine
C
Chavoix
Chantal
C
Defer
Gilles Louis
GL
Baron
Jean-Claude
JC
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008569:Memory Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D014055:Tomography, Emission-Computed / Q000379:methods*