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

ABSTRACT

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.