Highlights
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Clinical presentation of idiopathic normal pressure hydrocephalus may vary across geographic areas.
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Hypertension and hyperlipidemia were the most prevalent vascular risk factors, differing from previous studies where diabetes was the second most common.
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Age and education significantly predicted cognitive outcomes, while age was the only predictor of gait performance.
Introduction
Idiopathic normal pressure hydrocephalus (iNPH) is a condition that typically occurs in later life without an identifiable cause. It is characterized by a triad of progressive symptoms: gait disturbances, urinary dysfunction and cognitive impairment. These manifestations are associated with ventriculomegaly and normal cerebrospinal fluid (CSF) pressure. Reference Nakajima, Yamada and Miyajima1,Reference Relkin, Marmarou, Klinge, Bergsneider and Black2 Due to its nonspecific symptoms, iNPH is often misdiagnosed. Reference Graff-Radford and Jones3 Early detection is critical, as timely intervention can lead to clinical improvement in up to 80% of patients, Reference Wikkelsø, Hellström, Klinge and Tans4 whereas failure to treat leads to progressive symptom exacerbation and irreversible loss of autonomy. Reference Kiefer and Unterberg5,Reference Toma, Stapleton, Papadopoulos, Kitchen and Watkins6 Therefore, improving diagnostic accuracy is essential to optimize patient outcomes.
Vascular mechanisms are considered a key factor in the development of iNPH, with hypertension (65%) and diabetes (25%) being the most prevalent and well-studied risk factors. Reference Cai, Yang and Gao7 Other vascular risk factors, such as hyperlipidemia, overweight, smoking and coronary heart disease, have been investigated but remain less well documented, which may explain inconsistencies in their reported association with iNPH. Reference Cai, Yang and Gao7–Reference Eklund, Israelsson, Brunström, Forsberg and Malm11 Differences in clinical versus standardized diagnostic guidelines (e.g., American-EuropeanReference Relkin, Marmarou, Klinge, Bergsneider and Black 2 or JapaneseReference Nakajima, Yamada and Miyajima 1 ) further complicate study comparisons. In addition, most studies have focused on populations in Asia and Europe, raising concerns about the geographic generalizability of the findings. Notably, a study conducted in Hawaii found no significant association between vascular risk factors and iNPH in that region, suggesting that regional differences may influence the relationship. Reference Ghaffari-Rafi, Gorenflo, Hu, Viereck and Liow12 These observations underscore the need for further research in other geographic areas to determine the generalizability of current findings. To date, no studies have investigated iNPH in the province of Quebec, Canada.
Moreover, a comprehensive evaluation of cognitive and gait impairments is essential for accurate iNPH identification. Cognitive assessments are often limited to a single screening tool such as the Montreal Cognitive Assessment (MoCA) Reference Nasreddine, Phillips and Bédirian13 or the Mini-Mental State Examination, Reference Folstein, Folstein and McHugh14 even though detailed neuropsychological testing is increasingly advocated. Reference Nakajima, Yamada and Miyajima1,Reference Saito, Nishio and Kanno15,Reference Nimni, Weiss, Cohen and Laviv16 Priority needs to be given to fronto-subcortical deficits, including executive function, psychomotor speed, attention and working memory. Reference Nakajima, Yamada and Miyajima1,Reference Nimni, Weiss, Cohen and Laviv16–Reference Laidet, Herrmann, Momjian, Assal and Allali20 Tests such as Coding and Symbol Search subtests from the WAIS-III, Reference Wechsler21 Grooved Pegboard, Reference Klove22,Reference Kamohara, Nakajima and Kawamura23 Stroop Reference Kamohara, Nakajima and Kawamura23 and verbal fluency Reference Nimni, Weiss, Cohen and Laviv16,Reference Laidet, Herrmann, Momjian, Assal and Allali20,Reference Allali, Laidet and Armand24 tasks are recommended. Reference Nakajima, Yamada and Miyajima1 Similarly, while gait and balance disturbances are traditionally assessed using grading scales based on clinician observations, Reference Kubo, Kazui and Yoshida25 objective measures such as the Timed Up and Go test (TUG), Reference Mendes, de Oliveira and Pinto26–Reference Sundström, Rydja, Virhammar, Kollén, Lundin and Tullberg28 10-meter walk test (10MWT) Reference Sundström, Rydja, Virhammar, Kollén, Lundin and Tullberg28,Reference Chunyan, Rongrong and Youping29 and Berg Balance Scale (BBS) Reference Mori, Collino and Marzi30,Reference Gallagher, Marquez and Osmotherly31 are strongly recommended. Although test batteries have been proposed for iNPH, Reference Nimni, Weiss, Cohen and Laviv16,Reference Laidet, Herrmann, Momjian, Assal and Allali20,Reference Allali, Laidet and Armand24,Reference Roman, Takkar and Maiti32 their sensitivity remains limited by reliance on raw scores that do not account for individual demographic factors.
Demographic factors such as age, sex, and education significantly influence neuropsychological, Reference Larouche, Tremblay and Potvin33–Reference Skogan, Oerbeck, Christiansen, Lande and Egeland35 and physiotherapy Reference Pondal and del Ser36,Reference Steffen, Hacker and Mollinger37 outcomes. Higher education and younger age are associated with better initial performance and more pronounced practice effects in cognitive testing, Reference Kiselica, Kaser, Webber, Small and Benge38,Reference Mitrushina, Boone, Razani and D’Elia39 particularly in cognitively intact individuals. Reference Calamia, Markon and Tranel40–Reference Jutten, Grandoit and Foldi43 In Alzheimer’s patients, for example, the impact of demographic factors seems to disappear. Reference Lubrini, Gozalbo, Vincent, Acedo, López-Arrieta and Garcia44–Reference Rubin, Storandt and Miller46 Moreover, a study on the TUG test indicates that age, sex and cognitive status significantly affect gait performance in older adults. Among individuals with mild cognitive impairment, women and older participants exhibit longer TUG completion times compared to men across the majority of age groups. Reference Ibrahim, Singh and Shahar47 Although these demographic influences are established in other conditions, their impact on cognitive and gait performance in iNPH remains underexplored. This gap is particularly critical given the need to repeat tests, such as the CSF tap test, to predict treatment response.
Given the geographic variability observed in some aspects of iNPH risk factors, it is essential to document the demographic, vascular, cognitive and gait/balance profiles of iNPH patients across diverse geographic areas. The documentation of such profiles would enhance screening accuracy and facilitate the development of more tailored protocols to predict treatment response, especially in geographic areas such as Quebec, where iNPH remains under-investigated. Hence, a retrospective chart review study was conducted at the Centre Hospitalier Universitaire de Québec – Hôpital de l’Enfant-Jésus (CHU-HEJ). The specialized Department of Neurological Sciences at CHU-HEJ is recognized as a large neurological center in Canada and serves as the reference clinic of neurology in Eastern Quebec. Since 2010, a standardized assessment battery has been implemented at CHU-HEJ for iNPH patients, targeting fronto-subcortical deficit and gait and balance tests. The primary objective is to provide a comprehensive description of the demographic, vascular, cognitive and gait/balance profiles of patients diagnosed with probable iNPH in Eastern Quebec, in accordance with the most recent guidelines established by the Japanese NPH Society. Reference Nakajima, Yamada and Miyajima1 Additionally, a secondary exploratory objective is to determine how demographic factors (age, sex, education) influence cognitive and gait performance in iNPH patients.
Methods
Study design
A retrospective medical chart review was conducted on data from 175 patients with probable iNPH between January 2010 and May 2022 at CHU-HEJ. The 2021 Japanese NPH Society diagnostic criteria were applied retrospectively to the entire cohort. Reference Nakajima, Yamada and Miyajima1 All patients underwent both MRI and a standardized CSF tap test. The presence of radiological signs consistent with probable iNPH was demonstrated in all 175 patients, including ventriculomegaly (Evans’ index ≥ 0.30) and disproportionately enlarged subarachnoid-space hydrocephalus. Following the CSF tap test, 119 patients were referred for shunt surgery based on clinically significant improvement, while 56 were not referred due to insufficient response. Of the patients referred, 114 patients underwent shunt surgery (5 patients declined surgery). Postoperative follow-up data were available for 94 of these patients, of whom 85 (90.4 %) met the criteria for definite iNPH based on clinical improvement. In the present study, the analysis was limited to baseline data from the 175 patients with probable iNPH. The post-shunt outcomes are reported exclusively for the purpose of documenting the final diagnostic classification.
Inclusion criteria included a diagnosis of probable iNPH, native French-speaking (since French is the most widely spoken language and the official language of Quebec) and completion of the protocol at CHU-HEJ. Patients with known risk factors for the development of secondary hydrocephalus (subarachnoid hemorrhage or meningitis) or congenital NPH were excluded. The information collected was double-entered, and the two entries were compared for quality assurance purposes. The extracted data were anonymized for analysis. The study was conducted with the ethical approval of the Comité d’éthique de la recherche du Centre Hospitalier Universitaire de Québec - Université Laval (Project #2021-5509).
Patients’ demographic and vascular risk factors
Age, biological sex and number of years of formal education were obtained from the patients’ medical records on their first day of admission. To assess vascular risk factors, history of hypertension, diabetes mellitus, hyperlipidemia, stroke or transient ischemic attack, coronary artery disease, smoking and alcohol high-risk consumption were noted. A history of hypertension or hyperlipidemia was defined as a previous (or concomitant) diagnosis (or use of antihypertensive medication or statins); diabetes mellitus as a concomitant diagnosis; stroke or transient ischemic attack as a previous diagnosis of ischemic or hemorrhagic stroke or transient ischemic attack; and coronary artery disease as a concomitant diagnosis of myocardial infarction or angina pectoris. Smoking and alcohol consumption were assessed using data from interviews and clinical examinations. Smoking was defined as past or current cigarette smoking. Alcohol consumption was defined as current high-risk consumption, based on the Canadian Low-Risk Alcohol Drinking Guidelines. Reference Butt, Beirness, Gliksman, Paradis and Stockwell48
Neuropsychological assessment
Neuropsychological assessment focused on cognitive domains corresponding to evidence-based deficits in patients with iNPH. Reference Nimni, Weiss, Cohen and Laviv16,Reference Laidet, Herrmann, Momjian, Assal and Allali20,Reference Devito, Pickard, Salmond, Iddon, Loveday and Sahakian49–Reference Peterson, Savulich, Jackson, Killikelly, Pickard and Sahakian51 The assessment included a detailed evaluation of psychomotor speed, information processing speed, attention, short-term and working memory and executive functions. The administered tests were as follows: MoCA, Reference Nasreddine, Phillips and Bédirian13 Grooved Pegboard test, Reference Skogan, Oerbeck, Christiansen, Lande and Egeland35,Reference Strauss, Sherman and Spreen52 Delis-Kaplan Executive Function System (Trail Making Test conditions 1 to 5, Color-Word Interference [color naming, word reading and inhibition]), Reference Delis, Kaplan and Kramer53 alphabetic verbal fluency (F-A-S or T-N-P) and categorical verbal fluency (animals), Reference St-Hilaire, Hudon and Vallet34,Reference Delis, Kaplan and Kramer53 Weschler Adult Intelligence Scale IV (Symbol Search, Coding, Digit Span forward and backward) Reference Wechsler21 and Neuropsychological Assessment Battery (Number and Letters subtests Part A). Reference Stern and White54 Eighteen neuropsychological variables (scores) were selected for analysis. The tests were administered by qualified neuropsychologists according to standardized instructions for each test, except where noted. The 18 variables retained and the modifications made to the administration are presented in Table 1.
Table 1. Neuropsychological and gait/balance assessments: tests, modifications to instructions and variables retained for analysis
Note: 10MWT = 10-meter walk test.
Gait/balance assessment
Gait and balance tests were selected to assess evidence-based gait (10MWT – Normal Pace, Reference Kim, Park, Lee and Lee55 10MWT – Dual-Task Reference Lilja-Lund, Nyberg, Maripuu and Laurell56 ) and balance (TUG, Reference Podsiadlo and Richardson57 BBS Reference Berg, Wood-Dauphinee, Williams and Maki58 ) disturbances in patients with iNPH. Reference Wikkelsø, Hellström, Klinge and Tans4,Reference Chunyan, Rongrong and Youping29,Reference Gallagher, Marquez and Osmotherly31,Reference Lilja-Lund, Nyberg, Maripuu and Laurell56 Four gait/balance variables (scores) were selected for analysis. The tests were performed by qualified physiotherapists according to standardized instructions for each test, except where noted. The four variables retained and the modifications made to the administration are presented in Table 1.
Statistical analyses
To characterize the demographic, vascular, cognitive, and gait/balance profiles of probable iNPH patients who underwent the protocol, descriptive statistics were performed using IBM SPSS Statistics 29.0 software. Certain data were unavailable due to inherent constraints of the clinical setting, where some assessments were not systematically conducted due to factors such as limited time. Therefore, the number of data collected for each variable is indicated in each table.
To assess whether each demographic factor had an independent effect on cognitive and gait/balance test results, multiple linear regressions (standard) were performed for each cognitive and physical outcome. Analyses were performed using SAS 9.4 software, with an alpha threshold of 5 %. For each model, assumptions of normality and homogeneity of residual variance were tested.
Results
Demographics and frequency of vascular risk factors
Table 2 presents the patients’ demographics and the frequency of vascular risk factors in the sample. The cohort had a slight male predominance (53 %). The age of patients ranged between 60 and 90 years, and the range of years of formal education varied between 3 and 23 years. Hypertension and hyperlipidemia were the most prevalent vascular risk factors.
Table 2. Demographics and frequency of comorbid vascular risk factors of probable iNPH patients
Note: Data are presented as n/N (%); n = number of persons with corresponding risk factor; N = number of persons from the total sample who were examined for the corresponding risk factors. iNPH = idiopathic normal pressure hydrocephalus; SD = standard deviation; TIA = transient ischemic attack.
Cognitive and gait/balance results
Table 3 presents the patients’ cognitive profile, and Table 4 shows their gait/balance characteristics. The patients’ results across all measures of cognition and gait/balance showed substantial variability, as indicated by the large standard deviations and ranges. A total of 132 patients out of 152 scored less than the MoCA cut-off of 26/30 (scores of 25 or below indicate cognitive impairment Reference Nasreddine, Phillips and Bédirian13 ).
Table 3. Cognitive results of patients with probable iNPH
Note: iNPH = idiopathic normal pressure hydrocephalus; M = mean; SD = standard deviation; Med = median; MoCA = Montreal Cognitive Assessment; D-KEFS = Delis-Kaplan Executive Function System; TMT = Trail Making Test; WAIS-IV = Wechsler Adult Intelligence Scale-Fourth Edition; NAB = Neuropsychological Assessment Battery. *Efficiency is calculated with the formula ((236 - Numbers and letters Part A errors raw score)/Numbers and letters Part A speed raw score).
Table 4. Gait/balance results of probable iNPH patients
Note: iNPH = idiopathic normal pressure hydrocephalus; M = mean; SD = standard deviation; Med = median; 10MWT = 10-meter walk test; TUG = Timed Up and Go test; BBS = Berg Balance Scale. * The occurrence of errors in the cognitive task (counting down in leaps of 3 from 100) was not considered.
Demographic factors predicting cognitive and gait/balance results
Table 5 and Table 6 present the demographic factors that predicted cognitive and gait/balance results, respectively. Age and education (alone or together) predicted two-thirds of the cognitive test results, while biological sex did not predict any. Regarding gait/balance tests, only age was found to be a significant predictor of performance.
Table 5. Parameters estimate for variables predicting cognitive performances
Note: B = parameter estimate; SE = standard error of the parameter estimate; MoCA = Montreal Cognitive Assessment; D-KEFS = Delis-Kaplan Executive Function System; TMT = Trail Making Test; WAIS-IV = Wechsler Adult Intelligence Scale-Fourth Edition; NAB = Neuropsychological Assessment Battery. * p < 0.05 are in bold.
Table 6. Parameters estimate for variables predicting gait/balance performances
Note: B = parameter estimate; SE = standard error of the parameter estimate; 10MWT = 10-meter walk test; TUG = Timed Up and Go test; BBS = Berg Balance Scale. * p < 0.05 are in bold.
Discussion
The objective of this study was to provide a description of the demographic, vascular, cognitive and gait/balance profiles of patients diagnosed with probable iNPH in Eastern Quebec. The sample consisted of 53% men, with a mean age of 73.9 years and mean education level of 11.9 years. Hypertension was the most common vascular risk factor, followed by hyperlipidemia. The cognitive and gait/balance assessments exhibited substantial heterogeneity, as evidenced by large standard deviations and wide score ranges, reflecting marked inter-individual variability in the severity of impairment among iNPH patients. A secondary objective was to examine demographic predictors of cognitive and gait/balance outcomes. Biological sex had no significant impact, while age predicted most outcomes. Education influenced cognitive performance but not gait/balance measures.
The demographic, vascular, cognitive and gait/balance profiles of the patients with probable iNPH in this study were generally in line with those reported in the literature, with a few exceptions. In the sample, males constituted 53% of the patients compared to 47% females, representing only a modest male predominance. This contrasts with other studies that have reported a more pronounced overrepresentation of males. For instance, a recent Swedish prevalence study found that 2.1% of men had iNPH, compared to 0.96% of women, Reference Constantinescu, Wikkelsø and Westman59 and a study in Hawaii reported that men are 1.96 times more likely to develop iNPH than women. Reference Ghaffari-Rafi, Gorenflo, Hu, Viereck and Liow12 Regardless of geographic location, these findings consistently indicate a higher risk for iNPH in men, suggesting that sex-related differences, such as the higher aqueductal CSF stroke volumes and average flow rates observed in men, Reference Schmid Daners, Knobloch and Soellinger60,Reference Sartoretti, Wyss and Sartoretti61 may provide valuable insights into the underlying pathophysiology. Although the degree of male predominance observed in our study was less marked, the overall trend remains present.
This study evidenced that hypertension was the most common vascular risk factor in patients with iNPH in Quebec, as observed in previous studies. Reference Cai, Yang and Gao7,Reference Israelsson, Carlberg and Wikkelsö8,Reference Eide and Pripp62,Reference Graff-Radford and Godersky63 Hypertension has been widely studied for its potential involvement in the pathogenesis of iNPH, with proposed mechanisms including arterial stiffening and increased pulse pressure, which may exert greater mechanical force on brain tissue and contribute to ventricular dilation, a phenomenon known as the Windkessel effect. Reference Jaraj, Agerskov and Rabiei10,Reference Deng, Wang and Huang64–Reference Greitz69 In the literature, diabetes is the second most commonly reported vascular risk factor, with a prevalence of 25% in a recent meta-analysis. Reference Cai, Yang and Gao7 In this study, 26% of iNPH patients had diabetes. However, diabetes was not the second most common vascular comorbidity in the current sample. Hyperlipidemia, smoking and coronary artery disease were more common than diabetes. These findings suggest that the prevalence of vascular risk factors differs accross geographic areas, which may influence their association with iNPH. It is also possible that risk factors beyond hypertension and diabetes have been less frequently studied, leading to an underestimation of their relevance in iNPH. Notably, previous studies have reported inconsistencies across different populations. For instance, while European and Asian cohorts typically show an association between vascular comorbidities and iNPH, Reference Cai, Yang and Gao7,Reference Deng, Wang and Huang64,Reference Kuriyama, Miyajima and Nakajima70 a study conducted in Hawaii found no significant association. Reference Ghaffari-Rafi, Gorenflo, Hu, Viereck and Liow12 Such discrepancies may reflect differences in genetic susceptibility, lifestyle or environmental exposures. Similarly, the higher prevalence of certain vascular risk factors in the present cohort may be influenced by population-specific characteristics, such as socioeconomic status, gender and educational levels. Reference Adhikary, Barman, Ranjan and Stone71,Reference Di Cesare, Perel and Taylor72 The role of these factors in iNPH remains underexplored. To clarify their contribution, future studies should compare vascular risk profiles in iNPH patients and matched controls within Quebec, where demographic and lifestyle factors may differ from those studied in European and Asian cohorts.
The significant heterogeneity observed in cognitive and gait/balance profiles suggests substantial inter-individual variability in iNPH, which may reflect differences in disease stage. While the presence of the full triad (gait, cognitive, and urinary symptoms) is associated with more advanced stages of the disease, Reference Nakajima, Yamada and Miyajima1,Reference Kiefer and Unterberg5 there is currently no standardized framework for staging iNPH from early symptoms to severe impairment. Patients may be at different points along this continuum, ranging from subtle cognitive or gait/balance impairments to more pronounced dysfunction, contributing to the heterogeneity observed. This variability not only makes it challenging to identify iNPH patients based solely on baseline assessments but also likely reflects the complex clinical profiles and presence of comorbidities commonly seen in hospital-based cohorts referred to specialized neurological settings, as opposed to more narrowly selected research cohorts. This clinical complexity underscores the ecological validity of studying patients in real-world contexts and highlights the inherent challenges in diagnosing iNPH in such heterogeneous populations. Additionally, prior studies have reported similar variability in iNPH cohorts. Reference Nimni, Weiss, Cohen and Laviv16,Reference Laidet, Herrmann, Momjian, Assal and Allali20,Reference Bluett, Ash and Farheen73 Future research should aim to stratify patients based on symptom severity and identify clinical or biomarker-based predictors of disease progression. Given the diagnostic challenges posed by this heterogeneity, post-CSF tap test improvement remains an important element to support the diagnosis and predict surgical outcomes.
The findings of this study indicate that demographic factors significantly influence cognitive and gait/balance performance in iNPH patients, particularly age and education level. In a cognitively healthy population, it is well established in both neuropsychology and physiotherapy that individual performance declines with advancing age. Reference Murman74–Reference Salthouse77 However, in the context of cognitive pathology, the influence of age appears to differ. For instance, one study found that while advancing age was associated with decreased performance on a balance test and the MoCA in cognitively healthy individuals, these associations were not observed in patients with Parkinson’s disease. Reference Gallagher, Farella-Accurso and Johnson78 Similar findings have been reported in individuals with advanced-stage Alzheimer’s disease. Reference Rubin, Storandt and Miller46 However, the present results support the hypothesis that age exerts an influence on performance in iNPH patients, particularly in attentional, processing speed, executive functioning, gait and balance tasks.
Furthermore, education level was found to be associated with certain aspects of cognitive performance in iNPH patients. Higher education levels are known to enhance cognitive reserve and may delay the onset of cognitive decline. Reference Clouston, Smith and Mukherjee79–Reference Valenzuela and Sachdev82 However, this protective effect appears to diminish as cognitive impairment progresses. Reference Amieva, Mokri and Le Goff83 In the context of iNPH, cognitive deficits are rarely the first presenting symptoms of the triad. Reference Nakajima, Yamada and Miyajima1,Reference Isaacs, Williams and Hamilton84 Thus, it is plausible that some iNPH patients, particularly those in the early stages of cognitive decline, may continue to benefit from the protective effects of education. Additionally, higher education levels have been linked to a slower decline in executive functions. Reference Hindle, Martyr and Clare85 Given that several studies have established a connection between executive function and gait and balance performance Reference Iersel, Kessels, Bloem, Verbeek and Olde Rikkert86–Reference Hirota, Watanabe, Tanimoto, Kono, Higuchi and Kono88 one might expect education to similarly influence motor abilities. The present study found an association between education level and executive functioning in iNPH, specifically on TMT condition 4 and alphabetic verbal fluency tasks. However, no significant association was found between education level and gait or balance in iNPH patients. This contrasts with findings in other clinical populations, such as patients with Parkinson’s disease, where lower education levels have been associated with both poorer executive functioning (as measured by the Trail Making Test Part B, p = 0.018) and reduced balance (as measured by the BBS, p < 0.001). Reference Souza, Voos, Francato, Chien and Barbosa89 In summary, while education may modulate cognitive and motor interactions in some neurological conditions, its influence on gait and balance in iNPH remains ambiguous and warrants further investigation.
Interestingly, sex was not a significant predictor of cognitive or gait/balance outcomes, which contrasts with findings in non-iNPH older adults. For example, in cognitive testing, females have been reported to perform better than males on tasks assessing information processing speed, Reference Munro, Winicki and Schretlen90 such as Coding and Symbol Search subtests of the WAIS, Reference Roivainen, Suokas and Saari91 and psychomotor speed, such as the Grooved Pegboard test. Reference Ruff and Parker92 In the context of physiotherapy, the evidence is mixed. One study found no significant differences between males and females on the BBS, Reference Nakagawa, Ferraresi, Prata and Scheicher93 whereas another reported that females had lower scores than males. Reference Avdić and Skrbo94 The absence of sex-related differences in cognitive and gait/balance performance in iNPH patients observed in the present study may reflect the overriding impact of the disorder itself, which could mask the typical sex-based differences seen in healthy aging populations.
Overall, these findings support the notion that the impact of demographic factors differs in the iNPH population compared to other clinical populations and cognitively healthy individuals. Currently, the CSF tap test method is used to predict surgical response, with raw scores typically employed in the interpretation of outcomes. The results highlight the importance of thoroughly documenting demographic influences at baseline, as this foundational knowledge is essential for future research to evaluate their role in repeated assessments such as the CSF tap test. Understanding how demographic factors affect pre- and post-test performance could ultimately inform the integration of these factors into diagnostic and prognostic models, thereby refining assessment accuracy and supporting more individualized patient management.
Limitations
This study has limitations. The use of a hospital-based sample may have introduced a selection bias toward more severe cases, limiting the generalizability of the findings to the broader iNPH population. The retrospective design resulted in missing data, which may have affected the validity of some conclusions. Self-reported data on alcohol consumption and smoking may have been subject to recall bias. The neuropsychological protocol did not cover all cognitive domains, such as language (e.g., naming tasks), which could have supported differential diagnosis with other conditions, such as Alzheimer’s disease. Additionally, the extraction of data from medical records may have been influenced by variability in clinical documentation practices, despite quality control procedures. Finally, while this study focused on the impact of demographic factors, other potential factors such as medication use, comorbidities and disease duration were not assessed and may have influenced performance outcomes. Future research with prospective designs and larger, more diverse cohorts is needed to address these limitations.
Conclusion
This study is the first to characterize the demographic, vascular, cognitive and gait/balance profiles of iNPH patients in Eastern Quebec. The findings demonstrate that age and education level significantly influence cognitive performance, while age is the sole significant predictor of gait and balance outcomes. In contrast, sex was not associated with any cognitive or gait outcomes, suggesting that the underlying pathology may override typical sex-related differences observed in the aging population. Documenting these demographic influences is necessary to better interpret pre- and post-CSF tap test changes and to improve the accuracy of treatment response assessments.
The substantial heterogeneity in cognitive and gait/balance profiles underscores notable inter-individual variability, likely reflecting differences in disease stage, and highlights the need to broaden assessment protocols. Incorporating additional cognitive tests, such as measures targeting functions not classically impaired in iNPH, could improve differential diagnosis or help identify comorbidities. Furthermore, the high prevalence of vascular risk factors, particularly hypertension and hyperlipidemia, underscores the need for closer monitoring and targeted management of these comorbidities in iNPH patients. Although the effect of vascular comorbidity on long-term outcomes after shunt surgery remains unclear, Reference Eklund, Israelsson, Brunström, Forsberg and Malm11,Reference Andrén, Wikkelsö and Sundström95,Reference Spagnoli, Innocenti and Bello96 it may be associated with more severe symptoms and a negative influence on prognosis. Reference Hellström, Edsbagge, Archer, Tisell, Tullberg and Wikkelsø18,Reference Bådagård, Braun, Nilsson, Stridh and Virhammar97–Reference Kobayashi, Kanno and Kawakami99 Further studies with extended follow-up are needed to clarify the relationship between iNPH and vascular comorbidities. Finally, differences between this cohort and those reported in other geographic areas suggest that factors such as genetics or environment may contribute to the variability in iNPH clinical profiles. Larger prospective studies are needed to clarify these geographical variations and refine diagnostic and management strategies for diverse populations.
Acknowledgments
F.B-M. was supported by scholarships from the Canadian Institutes of Health Research (187549) and Fonds de Recherche du Québec (https://doi.org/10.69777/313551). This study was funded by the Normal Pressure Hydrocephalus Research Fund of the Clinique Interdisciplinaire de Mémoire at CHU-HEJ.
Author contribution
FBM, SC, LV and CH were involved in the conceptualization of the study. The methodology was developed by FBM, SC, YN, LV and CH. FBM and AN were responsible for project administration, as well as data collection. The formal analysis was conducted by FBM. SC, LV and CH provided supervision throughout the study. FBM wrote the original draft of the manuscript, and all authors contributed to the review and editing of the manuscript.
Funding statement
No targeted funding reported.
Competing interests
The authors have no potential conflicts of interest to disclose.
Open access
