Summary: A new PET imaging study shows that hallucinations and delusions that first appear after age 40 are often linked to underlying neurodegenerative changes. Using molecular positron emission tomography (PET), researchers found tau protein accumulation in roughly 65% of late-onset psychosis patients versus 15% of age-matched healthy controls, and amyloid beta positivity in 35% of patients compared with 2% of controls. These results provide direct in vivo evidence that late-life psychotic symptoms can reflect distinct neurodegenerative processes.
This research highlights how late-onset psychosis may be driven by biological changes also observed in dementia, informing diagnosis and potential personalized treatment strategies.
Key Facts
- High prevalence of tau pathology: About 65% of patients with psychosis beginning after age 40 showed tau PET positivity, more than four times the rate in healthy, age-matched controls (15%).
- Increased amyloid beta positivity: Amyloid PET was positive in 35% of late-onset psychosis patients compared with only 2% of healthy older adults.
- Two distinct pathological subtypes: PET imaging separated patients into an Alzheimer’s-type pattern (amyloid-positive with widespread tau distribution) and a non-Alzheimer’s-type pattern (amyloid-negative with more localized tau accumulation).
- Posterior brain tau localization in non-AD cases: In amyloid-negative patients, tau concentrated in posterior regions—particularly the parietal and occipital lobes—areas involved in visual processing, attention, and spatial cognition.
- Link to executive dysfunction: Among amyloid-positive patients, greater parietal tau burden correlated with poorer executive function, including planning and attentional control.
Source: QST
Background: Hallucinations and delusions that first occur in midlife or later are often treated as primary psychiatric disorders without clear biological explanations. This study, published in Molecular Psychiatry (August 2, 2026), indicates that many of these late-onset psychiatric symptoms may instead reflect underlying neurodegenerative pathology detectable with PET imaging.
The investigators used PET tracers for both amyloid and tau to examine 37 patients whose psychotic symptoms began after age 40 and 47 age-matched healthy controls. Tau imaging used florzolotau (18F), a tracer capable of visualizing a wide range of tau pathologies in the living brain, while amyloid imaging used 11C-PiB.
Results showed markedly higher rates of tau and amyloid positivity among patients than controls. Specifically, 24 of 37 patients (64.9%) were tau-positive versus 7 of 47 controls (14.9%), and 13 of 37 patients (35.1%) were amyloid-positive compared with one of 47 controls (2.1%). Beyond overall prevalence, the PET scans revealed distinct spatial patterns of tau accumulation: some patients matched an Alzheimer’s-type distribution, while others displayed posterior-predominant tau without amyloid deposition, suggesting non-Alzheimer’s tauopathies.
Posterior tau accumulation in amyloid-negative patients—centered on parietal and occipital cortices—may disrupt visual and spatial processing networks, potentially producing visual hallucinations, misperceptions, and related psychotic phenomena. In amyloid-positive cases, higher parietal tau correlated with worse performance on the Frontal Assessment Battery, linking tau burden to executive dysfunction commonly seen in dementia-related syndromes.
These findings represent the first direct in vivo demonstration that heterogeneous tau-related neurodegenerative changes can underlie late-onset psychosis. Earlier epidemiological and postmortem research had hinted at such links, but PET imaging now provides living-brain evidence that different neurodegenerative pathways may produce similar psychiatric symptoms.
Clinical implications include the potential to use PET biomarkers to differentiate Alzheimer’s-type from non-Alzheimer’s-type disease in patients presenting with new-onset psychosis late in life. Objective detection of amyloid and tau could improve diagnostic accuracy, guide treatment choices, and support development of targeted therapies tailored to the underlying pathology rather than focusing solely on psychiatric symptom management.
The research team emphasizes that late-onset psychosis places a heavy burden on patients, families, and caregivers, and that many affected individuals may not receive evaluations that include biological markers. PET-based assessment could help identify neurodegenerative contributors earlier, enabling more appropriate care planning, monitoring, and, potentially, disease-modifying interventions as such therapies are developed.
Key Questions Answered:
A: When psychotic symptoms first appear later in life, standard psychiatric assessments may miss underlying neurodegenerative causes because they rely primarily on symptom reports rather than biological imaging. Without biomarkers, clinicians can struggle to identify processes like tau and amyloid accumulation that influence prognosis and treatment response.
A: Florzolotau (18F) is a PET radiotracer that binds to diverse tau protein aggregates in the living brain. In this study, it enabled in vivo mapping of tau across both Alzheimer’s and non-Alzheimer’s tauopathy patterns, revealing heterogeneous tau involvement in late-onset psychosis.
A: The parietal and occipital lobes support visual perception, spatial awareness, attention, and sensory integration. Tau-related disruption in these posterior regions can impair processing of sensory information and reality monitoring, increasing the risk of visual hallucinations, distortions in spatial perception, and impaired judgment.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by staff to clarify clinical and research implications.
About this psychosis and neurology research news
Author: Rin Suzuki
Source: QST
Contact: Rin Suzuki – QST
Image: The image is credited to Neuroscience News
Original Research: Open access. “High prevalence of tau pathologies in late-onset psychosis: A PET study” by Manabu Kubota et al., Molecular Psychiatry. DOI: 10.1038/s41380-026-03749-3
Abstract
High prevalence of tau pathologies in late-onset psychosis: A PET study
Late-onset psychosis (LOP) differs clinically from younger-onset forms of psychosis, and prior postmortem and epidemiological work has suggested links between LOP and neurodegenerative conditions, particularly tauopathies. This PET study assessed the roles of Alzheimer’s disease (AD) and non-AD tauopathies in LOP using amyloid PET and tau PET with florzolotau (18F), a tracer that detects a broad range of tau pathologies.
Thirty-seven patients with LOP and 47 age-matched controls underwent PET with 11C-PiB and 18F-florzolotau to compare amyloid beta (Aβ) and tau accumulation. Diagnostic effects on regional 18F-florzolotau standardized uptake value ratios (SUVRs) were evaluated, and associations between regional SUVRs and cognitive and clinical features were analyzed separately for Aβ-positive and Aβ-negative subgroups.
Patients showed significantly higher positivity rates for Aβ (13 of 37 patients, 35.1%) and tau (24 of 37 patients, 64.9%) than controls (1 of 47 controls, 2.1% for Aβ; 7 of 47 controls, 14.9% for tau). A diagnostic effect on regional 18F-florzolotau SUVRs was observed (P = 0.004), with post-hoc analyses indicating increased retention in the parietal cortex; this effect persisted when restricting analysis to Aβ-negative participants (P = 0.002). In Aβ-positive patients, greater parietal tau burden correlated with lower Frontal Assessment Battery scores.
In conclusion, this in vivo PET study demonstrates a high prevalence of both AD-like and non-AD-like tau accumulation patterns in late-onset psychosis, indicating heterogeneous tau-related neurodegenerative contributions to this clinical syndrome.