Screening for a "trifecta" of executive function patterns in a large cohort of individuals with Parkinson's disease.

Abstract

Objective: This study examined three neurocognitive patterns or "clinical pearls" historically viewed as evidence for executive dysfunction in Parkinson disease (PD): 1) letter < category fluency; 2) word list < story delayed recall; 3) word list delayed recall < recognition. The association between intraindividual magnitudes of each neuropsychological pattern and individual performance on traditional executive function tests was examined.

Methods: A clinical sample of 772 individuals with PD underwent neuropsychological testing including tests of verbal fluency, word list/story recall, recognition memory, and executive function. Raw scores were demographically normed (Heaton) and converted to z-scores for group-level analyses.

Results: Letter fluency performance was worse than category fluency (d = -0.12), with 28% of participants showing a discrepancy of ≥ -1.0 SD. Delayed recall of a list was markedly poorer than story recall (d = -0.86), with 52% of the sample exhibiting ≥ -1.0 SD deficits. Lastly, delayed free recall was worse than recognition memory (d = -0.25), with 24% showing a discrepancy of ≥ -1.0 SD. These patterns did not consistently correlate with executive function scores. The word list < story recall pattern was more common in earlier than later PD stages and durations.

Conclusion: Among the three pearls, the most pronounced was stronger memory performance on story recall than word lists, observed in more than half the sample. Only ¼ the participants exhibited all three neurocognitive patterns simultaneously. The variability in patterns across individuals highlights the heterogeneity of cognitive impairment in PD and suggests that intra-individual comparisons may offer a more nuanced insight into cognitive functioning.