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

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.

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.

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.

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.