Prognostic value of amyloid PET scan in normal pressure hydrocephalus

Abstract

Amyloid positron emission tomography ([18F] florbetaben (FBB) PET) can be used to determine concomitant Alzheimer's disease (AD) in idiopathic normal pressure hydrocephalus (iNPH) patients. FBB PET scans and the tap test were performed in 31 patients with clinically suspected iNPH, and amyloid positive (iNPH/FBB+) and negative (iNPH/FBB-) groups were compared with respect to clinical characteristics. We evaluated prognostic value of FBB PET scans by analyzing the response to the tap test using a linear mixed model. We also performed a multivariable regression analysis to investigate whether amyloid PET positivity can predict the positive tap test response independent of other AD biomarkers. The results showed that the iNPH/FBB+ group (7/31, 22.6%) had a higher percentage of APOE4 carriers, lower Aβ42, higher CSF t-tau, and p-tau/Aβ42 ratio than the iNPH/FBB- group (24/31, 77.4%), while the two groups did not differ in imaging characteristics. The iNPH/FBB- group had a higher percentage of tap responders and showed a greater improvement in gait scores after the tap test than the iNPH/FBB+ group (group-tap test effect interaction, p = 0.035). A multivariable logistic regression analysis showed that amyloid positivity on PET scans (OR 0.03, p = 0.029) and CSF p-tau (OR 0.87, p = 0.044) were independently associated with the positive tap test response. Among 21 tap responders in the iNPH/FBB- group, 14 patients received shunt surgery and 12/14 (85.7%) patients showed symptom improvement. Our findings suggest that amyloid PET scans can help determine which iNPH patients will benefit from shunt surgery by discriminating concomitant AD.

Frontal Behavior Syndromes in Idiopathic Normal Pressure Hydrocephalus as a Function of Alzheimer’s Disease Biomarker Status

“…In addition, the presence or absence of AD biomarkers has demonstrated clinical significance in predicting response to neurosurgical interventions. For example, iNPH patients with negative Aβ positron emission tomography (PET) scans were more likely to demonstrate a reduction in gait disturbance following shunting (Jang et al, 2018). Similar findings regarding shunt response have been reported for CSF biomarkers of AD pathology, such as the p-tau/Aβ-42 ratio (Hong et al, 2018).…”

Usefulness of Brain Positron Emission Tomography with Different Tracers in the Evaluation of Patients with Idiopathic Normal Pressure Hydrocephalous

“…According to the SUVratio values, iNPH patients with high-SUVratio ( n = 5) and low-SUVratio ( n = 5) did not significantly differ for baseline clinical assessments and clinical improvement after shunt, but a significant inverse correlation between SUVratios and cognitive improvements after shunt was observed. Jang et al [ 26 ] evaluated the prognostic value of [ 18 F]Florbetaben by analyzing the response to the tap test in 31 iNPH patients. Compared to patients with negative PET ( n = 24), patients with positive PET ( n = 7) showed worse improvement in gait scores after the tap test.…”

“…According to the SUVratio values, iNPH patients with high-SUVratio (n = 5) and low-SUVratio (n = 5) did not significantly differ for baseline clinical assessments and clinical improvement after shunt, but a significant inverse correlation between SUVratios and cognitive improvements after shunt was observed. Jang et al [26] evaluated the prognostic value of [ 18…”

Update on Biomarkers For Amyloid Pathology in Alzheimer’s Disease

“…Cortical Aβ is not usually consistent with non-dementia Parkinson's (PD), with no Aβ PET retention observed; conversely when dementia is present with PD (PDD) both vascular and cortical Aβ deposition are present. Aβ PET scans have been shown to determine which idiopathic normal-pressure hydrocephalus (iNPH) patients will benefit from shunt surgery by discriminating concomitant AD [94]. With Aβ not being a pathological trait in FTLD and the clinical onset of the disease being similar to other dementias, Aβ PET has been useful in the differential diagnosis between FTLD, different FTLD aphasias and AD [95].…”