Reduced awareness of cognitive deficits in idiopathic normal pressure hydrocephalus and its change following lumbar puncture.

OBJECTIVE

Awareness of cognitive deficits is related to executive functions and may, therefore, be sensitive to the effects of lumbar puncture (LP) in idiopathic normal pressure hydrocephalus (iNPH). Although a reduction in awareness of cognitive deficits (RACD) has been previously described in iNPH, there is a lack of systematic, psychometrically validated reports. In this study, we investigated RACD and its LP-related changes in iNPH patients and compared them with those in clinical and healthy control groups.

METHODS

RACD was assessed before and after lumbar puncture (LP) in 24 patients (14 iNPH, 10 other age-associated cognitive syndromes; AACS) and compared with 23 healthy controls (HC), employing two RACD measures alongside cognitive examination. Local metacognition was measured using a visual percentile-based rating system and operationalized as the t-scaled distance between the participants' task-specific performance estimations and their objective test performance (ΔTSPE). Global metacognition, targeting broader estimates of cognitive functioning (ECF), was quantified by subtracting self- from informant-obtained sum scores on a questionnaire evaluating participants' dysexecutive problems (DEX-DS). Within-group and between-group differences in ΔTSPE and DEX-DS scores were compared non-parametrically, focusing on post-LP changes.

RESULTS

Averaged ΔTSPE was higher in the patient groups and mirrored the groups' lower objective test performance, while averaged DEX-DS showed no group difference. Following LP, group comparisons revealed iNPH-specific decrease in both RACD measures.

CONCLUSION

Our study revealed LP-related RACD changes in iNPH patients compared to those in AACS and HC participants. The results suggest a mitigation of impaired metacognitive abilities in iNPH, possibly resulting from LP-induced improvements in (local) metacognitive performance, facilitating ECF adjustment alongside a metacognitively stimulating testing procedure.