Impaired implicit sequence learning in Parkinson's disease patients with freezing of gait.
OBJECTIVE
Freezing of gait (FOG) in Parkinson's disease (PD) may involve specific impairments in acquiring automaticity under working memory load. This study examined whether implicit sequence learning, with or without a secondary task, is impaired in patients with FOG.


METHODS
Fourteen freezers (FRs), 14 nonfreezers (nFRs), and 14 matched healthy controls (HCs) performed a serial reaction time (SRT) task with a deterministic stimulus sequence under single-task (ST) and dual-task (DT) conditions. The increase in reaction times (RTs) for random compared with sequenced blocks was used as a measure of implicit sequence learning. Neuropsychological tests assessing global cognitive functioning and executive dysfunction were administered in order to investigate their relation to sequence learning.


RESULTS
nFRs and HCs showed significant implicit sequence learning effects (p < 0.001). FRs demonstrated a tendency to learn sequence-specific information in the SRT-ST task (p = 0.07) but not in the SRT-DT task (p = 0.69). Severity of FOG, however, correlated positively with SRT-DT task performance (r = -0.56; p < 0.05).


CONCLUSIONS
The present results suggest that PD patients suffering from FOG pathology exhibit a specific impairment in the acquisition of automaticity. When working memory capacity is supplementarily loaded by adding a DT, sequence learning in FRs becomes increasingly impaired. These findings indicate that therapies should focus on extensive training in acquiring novel motor activities and reducing working memory load to improve learning in FOG.
Research Unit for Cognitive Psychology.
Jochen
J
Vandenbossche
Research Unit for Cognitive Psychology.
Natacha
N
Deroost
Research Unit for Cognitive Psychology.
Eric
E
Soetens
Research Unit for Cognitive Psychology.
Daphné
D
Coomans
Department of Rehabilitation Sciences, Katholieke Universiteit Leuven.
Joke
J
Spildooren
Department of Rehabilitation Sciences, Katholieke Universiteit Leuven.
Sarah
S
Vercruysse
Department of Rehabilitation Sciences, Katholieke Universiteit Leuven.
Alice
0000-0003-1193-6229
A
Nieuwboer
Research Unit for Cognitive Psychology.
Eric
E
Kerckhofs
D000368:Aged; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology; D056344:Executive Function; D005260:Female; D046352:Freezing Reaction, Cataleptic / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000150:complications*; D006801:Humans; D007859:Learning Disabilities / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications*; D011930:Reaction Time / Q000502:physiology; D012691:Serial Learning / Q000502:physiology*; D013223:Statistics as Topic; D011795:Surveys and Questionnaires