A review of cognitive impairment and differential diagnosis in idiopathic normal pressure hydrocephalus

Molecular signatures of normal pressure hydrocephalus: a large-scale proteomic analysis of cerebrospinal fluid

Given the persistent challenge of differentiating idiopathic Normal Pressure Hydrocephalus (iNPH) from similar clinical entities, we conducted an in-depth proteomic study of cerebrospinal fluid (CSF) in 28 shunt-responsive iNPH patients, 38 Mild Cognitive Impairment (MCI) due to Alzheimer's disease, and 49 healthy controls. Utilizing the Olink Explore 3072 panel, we identified distinct proteomic profiles in iNPH that highlight significant downregulation of synaptic markers and cell-cell adhesion proteins. Alongside vimentin and inflammatory markers upregulation, these results suggest ependymal layer and transependymal flow dysfunction. Moreover, downregulation of multiple proteins associated with congenital hydrocephalus (e.g., L1CAM, PCDH9, ISLR2, ADAMTSL2, and B4GAT1) points to a possible shared molecular foundation between congenital hydrocephalus and iNPH. Through orthogonal partial least squares discriminant analysis (OPLS-DA), a panel comprising 13 proteins has been identified as potential diagnostic biomarkers of iNPH, pending external validation. These findings offer novel insights into the pathophysiology of iNPH, with implications for improved diagnosis.

Depressive symptoms, functional impairment, and health-related quality of life in idiopathic normal pressure hydrocephalus: A population-based study

BACKGROUND

Maximising quality of life is a central goal for all healthcare, especially when dealing with dementing disorders. In this study we aimed to compare health-related quality of life (HRQoL), depressive symptoms and functional impairment between individuals with and without idiopathic normal pressure hydrocephalus (iNPH) from the general population.

METHODS

A total of 122 individuals, 30 with iNPH (median age 75 years, 67 females) underwent neurological examinations and computed tomography of the brain with standardised rating of imaging findings and clinical symptoms. The participants completed the Geriatric Depression Scale (GDS-15) and the HRQoL instrument EQ5D-5L. In addition, the modified Rankin Scale (mRS) was used to evaluate functional impairment.

RESULTS

Compared with participants without iNPH, those with iNPH reported a higher score on GDS-15 (median 3 vs 1) and mRS (median 2 vs 1) (p < 0.05). Further, those with iNPH rated lower on EQ5D-5L (index 0.79, VAS 70) than those without iNPH (index 0.86, VAS 80) (p < 0.05). In logistic regression models, low HRQoL was associated with more depressive symptoms, a higher degree of iNPH symptoms, and lower functional status.

CONCLUSIONS

In this population-based sample, those with iNPH had more depressive symptoms, lower functional status, and worse quality of life compared to those without iNPH. The strongest association with low HRQoL was found for depressive symptoms, functional level, and degree of iNPH symptoms. These results underline the value of shunt surgery because of its potential to reduce symptoms and disability in iNPH and therefore improve HRQoL.

Application of LRG mechanism in normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a prevalent type of hydrocephalus, including secondary normal pressure hydrocephalus (SNPH) and idiopathic normal pressure hydrocephalus (INPH). However, its clinical diagnosis and pathological mechanism are still unclear. Leucine-rich α-2 glycoprotein (LRG) is involved in various human diseases, including cancer, diabetes, cardiovascular disease, and nervous system diseases. Now the physiological mechanism of LRG is still being explored. According to the current research results on LRG, we found that the agency of LRG has much to do with the known pathological process of NPH. This review focuses on analyzing the LRG signaling pathways and the pathological mechanism of NPH. According to the collected literature evidence, we speculated that LRG probably be involved in the pathological process of NPH. Finally, based on the mechanism of LRG and NPH, we also summarized the evidence of molecular targeted therapies for future research and clinical application.

Normal Pressure Hydrocephalus

Normal Pressure Hydrocephalus (NPH) occurs when there is an accumulation of cerebrospinal fluid due to impeded flow or excess production, resulting in gait and memory impairment and urinary incontinence. The authors present the case of a 67-year-old male, who had symptoms for a year prior to being diagnosed. His neurological exam was significant for a slow, and unsteady wide-based gait. No underlying cause for his NPH was found. He underwent a shunt procedure following which he made a complete recovery.

Ventriculoperitoneal Shunt Treatment Increases 7 Alpha Hy-Droxy-3-Oxo-4-Cholestenoic Acid and 24-Hydroxycholesterol Concentrations in Idiopathic Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is the most common form of hydrocephalus in the adult population, and is often treated with cerebrospinal fluid (CSF) drainage using a ventriculoperitoneal (VP) shunt. Symptoms of iNPH include gait impairment, cognitive decline, and urinary incontinence. The pathophysiology behind the symptoms of iNPH is still unknown, and no reliable biomarkers have been established to date. The aim of this study was to investigate the possible use of the oxysterols as biomarkers in this disease. CSF levels of the oxysterols 24S- and 27-hydroxycholesterol, as well as the major metabolite of 27-hydroxycholesterol, 7 alpha hydroxy-3-oxo-4-cholestenoic acid (7HOCA), were measured in iNPH-patients before and after treatment with a VP-shunt. Corresponding measurements were also performed in healthy controls. VP-shunt treatment significantly increased the levels of 7HOCA and 24S-hydroxycholesterol in CSF (p = 0.014 and p = 0.037, respectively). The results are discussed in relation to the beneficial effects of VP-shunt treatment. Furthermore, the possibility that CSF drainage may reduce an inhibitory effect of transiently increased pressure on the metabolic capacity of neuronal cells in the brain is discussed. This capacity includes the elimination of cholesterol by the 24S-hydroxylase mechanisms.

Flying under the radar: CDH2 (N-cadherin), an important hub molecule in neurodevelopmental and neurodegenerative diseases

CDH2 belongs to the classic cadherin family of Ca2+-dependent cell adhesion molecules with a meticulously described dual role in cell adhesion and β-catenin signaling. During CNS development, CDH2 is involved in a wide range of processes including maintenance of neuroepithelial integrity, neural tube closure (neurulation), confinement of radial glia progenitor cells (RGPCs) to the ventricular zone and maintaining their proliferation-differentiation balance, postmitotic neural precursor migration, axon guidance, synaptic development and maintenance. In the past few years, direct and indirect evidence linked CDH2 to various neurological diseases, and in this review, we summarize recent developments regarding CDH2 function and its involvement in pathological alterations of the CNS.

Update on the Cognitive Presentations of iNPH for Clinicians

This mini-review focuses on cognitive impairment in iNPH. This symptom is one of the characteristic triad of symptoms in a condition long considered to be the only treatable dementia. We present an update on recent developments in clinical, neuropsychological, neuroimaging and biomarker aspects. Significant advances in our understanding have been made, notably regarding biomarkers, but iNPH remains a difficult diagnosis. Stronger evidence for permanent surgical treatment is emerging but selection for treatment remains challenging, particularly with regards to cognitive presentations. Encouragingly, there has been increasing interest in iNPH, but more research is required to better define the underlying pathology and delineate it from overlapping conditions, in order to inform best practise for the clinician managing the cognitively impaired patient. In the meantime, we strongly encourage a multidisciplinary approach and a structured service pathway to maximise patient benefit.

Relationship between cognitive profile and neuroradiographic parameters in patients with idiopathic normal pressure hydrocephalus

Background: Normal pressure hydrocephalus (NPH) is a reversible type of dementia, which affects 0.2 to 5.9 percent of elders. It manifests with triad of gait disturbances, urinary incontinence, and cognitive decline. In this study, association between cognitive and neuroradiographic parameters of idiopathic NPH (iNPH) was appraised to find out possible biomarkers for preventive intervention. Methods: In a cross-sectional study, 16 patients with iNPH were evaluated for third and fourth ventricle diameter, diameter of temporal horn of lateral ventricle, Evans index (EI), callosal angle (CA), callosal bowing, and ballooning of frontal horn. The Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG) was used to take cognitive profile. Relation between brain magnetic resonance imaging (MRI) indices and cognitive domains was extracted, using generalized linear model (GLM). Results: Patients with mild callosal bowing had better function in memory (P = 0.050) and language (P = 0.001) than those with moderate to severe callosal bowing. Negative or mild ballooning of frontal horn was also associated with higher scores in memory (P = 0.010), executive function (EF) (P = 0.029), and language (P = 0.036) than moderate to severe ballooning of frontal horn. Increased 3rd ventricle diameter was associated with decline in total cognition (P = 0.008), memory (P = 0.019), EF (P = 0.012), and language (P = 0.001). Relation between other radiographic indices and cognitive function was not significant. Conclusion: Third ventricular diameter, rounding of frontal horn of lateral ventricle, and callosal bowing are more accurate neuroradiographic parameters to predict cognitive decline in iNPH.

CSF tap test in idiopathic normal pressure hydrocephalus: still a necessary prognostic test?

Objective

To assess whether gait, neuropsychological, and multimodal MRI parameters predict short-term symptom reversal after cerebrospinal fluid (CSF) tap test in idiopathic normal pressure hydrocephalus (iNPH).

Methods

Thirty patients (79.3 ± 5.9 years, 12 women) with a diagnosis of probable iNPH and 46 healthy controls (74.7 ± 5.4 years, 35 women) underwent comprehensive neuropsychological, quantitative gait, and multimodal MRI assessments of brain morphology, periventricular white-matter microstructure, cortical and subcortical blood perfusion, default mode network function, and white-matter lesion load. Responders were defined as an improvement of at least 10% in walking speed or timed up and go test 24 h after tap test. Univariate and multivariable tap test outcome prediction models were evaluated with logistic regression and linear support vector machine classification.

Results

Sixteen patients (53%) respondedpositively to tap test. None of the gait, neuropsychological, or neuroimaging parameters considered separately predicted outcome. A multivariable classifier achieved modest out-of-sample outcome prediction accuracy of 70% (p = .028); gait parameters, white-matter lesion load and periventricular microstructure were the main contributors.

Conclusions

Our negative findings show that short-term symptom reversal after tap test cannot be predicted from single gait, neuropsychological, or MRI parameters, thus supporting the use of tap test as prognostic procedure. However, multivariable approaches integrating non-invasive multimodal data are informative of outcome and may be included in patient-screening procedures. Their value in predicting shunting outcome should be further explored, particularly in relation to gait and white-matter parameters.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11168-x.

Change in Balance and Neuropsychological Measures Post-Lumbar Drain Trial in Patients with Suspected Normal Pressure Hydrocephalus

OBJECTIVE

Ventriculoperitoneal (VP) shunting is commonly used to treat normal pressure hydrocephalus (NPH). Assessment of cognition and balance pre- and post-lumbar drain (LD) can be used to provide objective metrics which may help determine the potential benefit of VP shunting. The aim of this investigation was to determine which measures identify clinical change as a result of a LD trial and to develop recommendations for standard NPH clinical assessment procedures.

METHODS

The Berg Balance Scale (BBS) and a brief battery of commonly used neuropsychological tests pre- and post-LD (MMSE, trail making test, animal fluency, Hopkins Verbal Learning Test - Revised, and digit span) were administered to 86 patients with a diagnosis of NPH. Subjects were divided into groups based on whether or not clinical change was present, and thus, VP shunting was recommended post-LD, and predictors of group membership were examined.

RESULTS

Significant improvements (p < 0.05) were seen on the BBS and Trail Making Part B in the VP shunt-recommended group, with no other significant changes over time in either group. Regression analyses found that VP shunt recommendation was accurately predicted for 80% of the sample using the BBS score alone, with accuracy increasing to 85% when Trails B was added.

CONCLUSIONS

Scores from the BBS and Trails B were most likely to change in those chosen to undergo VP shunting post-LD. Given that the typical clinical presentation of NPH includes gait disturbance and cognitive impairment, it is recommended that a standard pre-/post-LD evaluation include the BBS and trail making test.

Pathophysiological Mechanisms Underlying Idiopathic Normal Pressure Hydrocephalus: A Review of Recent Insights

The pathophysiologic mechanisms underpinning idiopathic normal pressure hydrocephalus (iNPH), a clinically diagnosed dementia-causing disorder, continue to be explored. An increasing body of evidence implicates multiple systems in the pathogenesis of this condition, though a unifying causative etiology remains elusive. Increased knowledge of the aberrations involved has shed light on the iNPH phenotype and has helped to guide prognostication for treatment with cerebrospinal fluid diversion. In this review, we highlight the central role of the cerebrovasculature in pathogenesis, from hydrocephalus formation to cerebral blood flow derangements, blood-brain barrier breakdown, and glymphatic pathway dysfunction. We offer potential avenues for increasing our understanding of how this disease occurs.

Neuropsychological assessments and cognitive profile mostly associated with shunt surgery in idiopathic normal pressure hydrocephalus patients: diagnostic and predictive parameters and practical implications

BACKGROUND

Cognitive decline is a well-documented feature of idiopathic normal pressure hydrocephalus (iNPH) that can be reversible following cerebrospinal fluid tap tests (CSF-TT). The current gold standard for selecting iNPH patients for shunt surgery is measurable improvement in gait tests following CSF-TT. However, the diagnostic significance and predictive role of pre-surgical cognitive evaluations in probable iNPH patients is still controversial.

PURPOSE

To find the neuropsychological (NPSY) tests and cognitive aspects mostly associated with shunt surgery in iNPH.

MATERIAL AND METHODS

A retrospective comparison between probable iNPH patients who, after undergoing CSF-TT with gait and cognitive evaluations, ended up receiving a shunt (group 1) and probable iNPH patients who ended up with no shunt surgery (group 2). Differences in the diagnostic and predictive results of variety of NPSY tests at baseline, pre-CSF-TT, and post-CSF-TT were used for thorough statistical calculations.

RESULTS

A total of 147 patients with probable iNPH were included. Of those, 58 (39.45%, group 1) patients underwent shunt surgery, while 89 (60.55%, group 2) did not. For the vast majority of the cognitive tests used, no statistically significant differences were found between the groups at baseline (pre-CSF-TT). Following CSF-TT, the "naming" component of the Cognistat test was the only single test to show statically significant difference in improvement between the two groups. Combining at least two tests led to increased levels of accuracy and specificity; however, the sensitivity remained < 50. The only two combinations that were associated with sensitivity ≥ 70 were either any improvement in the Cognistat test (p = 0.627) or any improvement in either its naming, memory, or judgment components (p = 0.015).

CONCLUSION

Cognitive tests, even when combined to cover several cognitive aspects, are not sensitive enough to act as an independent reliable diagnostic and predictive tool, especially when relying on their scores as baseline. In order to avoid cumbersome and unnecessary tests to our patients and to reduce the number of patients who are denied proper treatment due to misdiagnosis, we recommend to use NPSY tests that examine the cognitive aspects of naming and memory, in addition to 2-3 tests for executive functions.

Amide Proton Transfer-Weighted MRI Might Help Distinguish Amnestic Mild Cognitive Impairment From a Normal Elderly Population

Objectives: To evaluate whether 3D amide proton transfer weighted (APTw) imaging based on magnetization transfer analysis can be used as a novel imaging marker to distinguish amnestic mild cognitive impairment (aMCI) patients from the normal elderly population by measuring changes in APTw signal intensity in the hippocampus and amygdala. Materials and Methods: Seventy patients with aMCI and 74 age- and sex-matched healthy volunteers were recruited for routine MRI and APT imaging examinations. Magnetic transfer ratio asymmetry (MTRasym) of the amide protons (at 3.5 ppm), or APTw values, were measured in the bilateral hippocampus and amygdala on three consecutive cross-sectional APT images and were compared between the aMCI and control groups. The independent sample t-test was used to evaluate the difference in APTw values of the bilateral hippocampus and amygdala between the aMCI and control groups. Receiver operator characteristic analysis was used to assess the diagnostic performance of the APTw. The paired t-test was used to assess the difference in APTw values between the left and right hippocampus and amygdala, in both the aMCI and control groups. Results: The APTw values of the bilateral hippocampus and amygdala in the aMCI group were significantly higher than those in the control group (left hippocampus 1.01 vs. 0.77% p < 0.001; right hippocampus 1.02 vs. 0.74%, p < 0.001; left amygdala 0.98 vs. 0.70% p < 0.001; right amygdala 0.94 vs. 0.71%, p < 0.001). The APTw values of the left amygdala had the largest AUC (0.875) at diagnosis of aMCI. There was no significant difference in APTw values between the left and right hippocampus and amygdala, in either group. (aMCI group left hippocampus 1.01 vs. right hippocampus 1.02%, p = 0.652; healthy control group left hippocampus 0.77 vs. right hippocampus 0.74%, p = 0.314; aMCI group left amygdala 0.98 vs. right amygdala 0.94%, p = 0.171; healthy control group left amygdala 0.70 vs. right amygdala 0.71%, p = 0.726). Conclusion: APTw can be used as a new imaging marker to distinguish aMCI patients from the normal elderly population by indirectly reflecting the changes in protein content in the hippocampus and amygdala.

Feasibility of action observation effect on gait and mobility in idiopathic normal pressure hydrocephalus patients

Action observation (AO) has been proved to be of benefit in several neurological conditions, but no study has previously been conducted in idiopathic normal pressure hydrocephalus (iNPH).

The Pathogenesis Based on the Glymphatic System, Diagnosis, and Treatment of Idiopathic Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a rare neurological disorder with no clear prevalence factors and is a significant danger to the elderly. The intracranial glymphatic system is the internal environment that maintains brain survival and metabolism, and thus fluid exchange changes in the glymphatic system under various pathological conditions can provide important insights into the pathogenesis and differential diagnosis of many neurodegenerative diseases such as iNPH. iNPH can be diagnosed using a combination of clinical symptoms, imaging findings and history, and cerebrospinal fluid biomarkers due to the glymphatic system disorder. However, only few researchers have linked the two. Shunt surgery can improve the glymphatic system disorders in iNPH patients, and the surgical approach is determined using a combination of clinical diagnosis and trials. Therefore, we have composed this review to provide a future opportunity for elucidating the pathogenesis of iNPH based on the glymphatic system, and link the glymphatic system to the diagnosis and treatment of iNPH. The review will provide new insights into the medical research of iNPH.

Dynamic functional networks in idiopathic normal pressure hydrocephalus: Alterations and reversibility by CSF tap test

Idiopathic Normal Pressure Hydrocephalus (iNPH)—the leading cause of reversible dementia in aging—is characterized by ventriculomegaly and gait, cognitive and urinary impairments. Despite its high prevalence estimated at 6% among the elderlies, iNPH remains underdiagnosed and undertreated due to the lack of iNPH‐specific diagnostic markers and limited understanding of pathophysiological mechanisms. INPH diagnosis is also complicated by the frequent occurrence of comorbidities, the most common one being Alzheimer's disease (AD). Here we investigate the resting‐state functional magnetic resonance imaging dynamics of 26 iNPH patients before and after a CSF tap test, and of 48 normal older adults. Alzheimer's pathology was evaluated by CSF biomarkers. We show that the interactions between the default mode, and the executive‐control, salience and attention networks are impaired in iNPH, explain gait and executive disturbances in patients, and are not driven by AD‐pathology. In particular, AD molecular biomarkers are associated with functional changes distinct from iNPH functional alterations. Finally, we demonstrate a partial normalization of brain dynamics 24 hr after a CSF tap test, indicating functional plasticity mechanisms. We conclude that functional changes involving the default mode cross‐network interactions reflect iNPH pathophysiological mechanisms and track treatment response, possibly contributing to iNPH differential diagnosis and better clinical management.

Normal pressure hydrocephalus: Diagnostic delay

Introduction:

Normotensive hydrocephalus is a differential diagnosis in the evaluation of the dementia syndrome. The diagnostic protocols would allow detecting this pathology that has more effective treatment than other dementias.

Objective:

To describe a population with clinical suspicion of normal pressure hydrocephalus evaluated in a Colombian psychiatric hospital and discuss the possible reasons for its diagnostic and therapeutic delay.

Materials and methods:

We conducted a retrospective study of medical records to identify patients with suspected normal pressure hydrocephalus during a 5-year period.

Results:

Thirty-five patients with suspected normal pressure hydrocephalus underwent diagnostic lumbar puncture and five of them were considered candidates for a peritoneal-venous shunt, but none underwent this surgical procedure. After three to six months of the lumbar puncture, the gait pattern improved in 22.8% of the patients, cognition in 22.8%, and sphincter control in 11.4%. Improvement was not sustained in the long term (1 year) in any of them.

Conclusion:

This study suggests the poor implementation of the protocols for evaluating patients with cognitive deficits and delays in the diagnosis of normal pressure hydrocephalus. A small number of patients were identified as candidates for treatment. Normal pressure hydrocephalus is a potentially reversible clinical entity with the placement of a peritoneal ventricular shunt, but delays in diagnosis and treatment have deleterious consequences for patients and their families.

Current Update on Treatment Strategies for Idiopathic Normal Pressure Hydrocephalus

PURPOSE OF REVIEW

Idiopathic normal pressure hydrocephalus (iNPH) is a surgically treatable neurological disorder of the elderly population that is characterized by abnormal ventricular enlargement due to cerebrospinal fluid (CSF) accumulation and gait disturbance, cognitive impairment, or urinary incontinence. The objective of this review is to present the current diagnostic and treatment approaches for iNPH and to discuss some of the postoperative modalities that complement positive surgical outcomes.

RECENT FINDINGS

Although historically reported patient outcomes following iNPH surgery were dismal and highly variable, recent advances in terms of better understanding of the iNPH disease process, better standardization of iNPH diagnostic and treatment processes arising from the adoption of clinical guidelines for diagnosis, treatment and in research methodologies, and availability of long-term follow-up data, have helped reduce the variations to a much improved 73 to 96% reported good outcomes. With careful evaluation, good patient selection, and advanced surgical techniques, iNPH can be surgically treated to return patients close to their pre-iNPH functional status. Institution of an interdisciplinary effort to rehabilitate patients following surgery may help augment their recovery.

Cerebrospinal fluid biomarkers profile of idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a disabling neurological disorder whose potential treatability is significantly limited by diagnostic uncertainty. In fact, typical clinical presentation occurs at late phases of disease, when CSF shunting could be ineffective. In recent years, measurement of different CSF proteins, whose concentration directly reflects neuropathological changes of CNS, has significantly improved both diagnostic timing and accuracy of neurodegenerative disease. Unfortunately iNPH lacks neuropathological hallmarks allowing the identification of specific disease biomarkers. However, neuropathology of iNPH is so rich and heterogeneous that many processes can be tracked in CSF, including Alzheimer's disease core pathology, subcortical degeneration, neuroinflammation and vascular dysfunction. Indeed, a huge number of CSF biomarkers have been analyzed in iNPH patients, but a unifying profile has not been provided yet. In this brief survey, we thus attempted to summarize the main findings in the field of iNPH CSF biomarkers, aimed at outlining a synthetic model. Although defined cut-off values for biomarkers are not available, a better knowledge of CSF characteristics may definitely assist in diagnosing the disease.

Spectrum of cognitive disorders in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by ventricular dilation accompanied by a progressive triad of a gait disturbance, "dementia" and incontinence. We retrospectively evaluated cognitive profile, and its relationship with disease variables, in 64 iNPH patients. The iNPH group performed significantly worse than the control group on all neuropsychological tests, except for verbal memory (within the normal range). The patients were subdivided into four groups: group 1 (42%: global cognitive impairment); group 2 (24%: frontosubcortical dysfunction); group 3 (17%: isolated deficit of a single cognitive domain); group 4 (17%: no cognitive impairment). Group 1 was older, with a significantly longer disease duration and more severe motor disease, while groups 3 and 4 were younger and presented milder motor impairment and a shorter disease duration. These data suggest parallel progression of cognitive and motor impairment in iNPH; early shunt surgery might prevent the development, in older age, of dementia in these patients.

Early Idiopathic Normal Pressure Hydrocephalus Patients With Neuropsychological Impairment Are Associated With Increased Fractional Anisotropy in the Anterior Thalamic Nucleus

In this study, we aimed to investigate the reactive changes in diffusion tensor imaging (DTI)-derived diffusion metrics of the anterior thalamic nucleus (AN), a relaying center for the Papez circuit, in early idiopathic normal pressure hydrocephalus (iNPH) patients with memory impairment, as well as its correlation with the patients' neuropsychological performances. In total, 28 probable iNPH patients with symptom onset within 1 year and 17 control subjects were prospectively recruited between 2010 and 2013 for this institutional review board-approved study. Imaging studies including DTI and a neuropsychological assessment battery were performed in all subjects. Diffusion metrics were measured from the region of the AN using tract-deterministic seeding method by reconstructing the mammillo-thalamo-cingulate connections within the Papez circuit. Differences in diffusion metrics and memory assessment scores between the patient and control group were examined via the Mann-Whitney U test. Spearman correlation analyses were performed to examine associations between diffusion metrics of AN and neuropsychological tests within the patient group. We discovered that early iNPH patients exhibited marked elevations in fractional anisotropy, pure diffusion anisotropy, and axial diffusivity (all P < 0.01), as well as lower neuropsychological test scores including verbal and nonverbal memory (all P < 0.05) compared with normal control. Spearman rank correlation analyses did not disclose significant correlations between AN diffusion metrics and neuropsychological test scores in the patient group, whereas ranked scatter plots clearly demonstrated a dichotic sample distribution between patient and control samples. In summary, our study highlighted the potential compensatory role of the AN by increasing thalamocortical connectivity within the Papez circuit because memory function declines in early iNPH when early shunt treatment may potentially reverse the memory deficits.