Neuropsychological Profile of Normal Pressure Hydrocephalus: A Systematic Review of Cognitive Trajectories and...

Cognitive impairment is a key yet understudied component of normal pressure hydrocephalus (NPH). Although gait and radiological markers are routinely assessed, neuropsychological outcomes remain inconsistently reported, and no standardized cognitive battery exists for evaluating patients before and after cerebrospinal fluid shunt. This systematic review synthesizes available evidence on the cognitive trajectories of adults with NPH and identifies the neuropsychological tests that are most sensitive and clinically informative for monitoring outcomes following ventriculo-peritoneal and lumbo-peritoneal shunts.

A systematic search of PubMed/MEDLINE and Web of Science identified studies reporting standardized neuropsychological assessments in adult NPH. Ten studies met inclusion criteria. Because statistical reporting varied across studies (means/standard deviation [SD] vs. medians/interquartile range), nonparametric data were harmonized into estimated means and SDs using validated transformation methods. Weighted means and pooled SDs were computed for each test and follow-up interval (T0, 3, 6, 12, and 24 months), enabling comparison of cognitive trajectories across domains, with values rounded according to appropriate significant digit conventions to enhance clinical interpretability.

Across 537 baseline assessments, the Mini-Mental State Examination (MMSE) was most frequently administered, followed by Trail Making Test A (TMT-A), Trail Making Test B (TMT-B), Digit Span, Verbal Fluency, and the Frontal Assessment Battery. Aggregated results revealed modest domain-specific and time-dependent postoperative improvements. Global cognition (MMSE) improved steadily up to 12 months, psychomotor speed and attention (TMT-A) improved early, and executive functions (TMT-B, Frontal Assessment Battery) showed later gains peaking at 12 months. Working memory (Digit Span) and verbal fluency improved more variably and often later. Variability across studies was reflected in pooled SDs. Across measures, MMSE, TMT-A, TMT-B, and Digit Span were the most robust and sensitive indicators of postoperative cognitive change.

Cognitive recovery after shunt in NPH follows a predominantly fronto-subcortical pattern, with the greatest improvements occurring within the first postoperative year. MMSE, TMT-A, TMT-B, and Digit Span represent the most reliable and informative neuropsychological tools for preoperative and postoperative evaluation and should constitute the core of a standardized NPH-specific cognitive battery. Establishing uniform testing protocols and improving methodological consistency across studies will enhance diagnostic accuracy, surgical decision-making, and long-term monitoring of this treatable condition.