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Overestimation in angular path integration precedes Alzheimer's dementia.

ABSTRACT: Path integration (PI) is impaired early in Alzheimer's disease (AD) but reflects multiple sub-processes that may be differentially sensitive to AD. To characterize these sub-processes, we developed a novel generative linear-angular model of PI (GLAMPI) to fit the inbound paths of healthy elderly participants performing triangle completion, a popular PI task, in immersive virtual reality with real movement. The model fits seven parameters reflecting the encoding, calculation, and production errors associated with inaccuracies in PI. We compared these parameters across younger and older participants and patients with mild cognitive impairment (MCI), including those with (MCI+) and without (MCI-) cerebrospinal fluid biomarkers of AD neuropathology. MCI patients showed overestimation of the angular turn in the outbound path and more variable inbound distances and directions compared with healthy elderly. MCI+ were best distinguished from MCI- patients by overestimation of outbound turns and more variable inbound directions. Our results suggest that overestimation of turning underlies the PI errors seen in patients with early AD, indicating specific neural pathways and diagnostic behaviors for further research.

SUBMITTER: Castegnaro A

PROVIDER: S-EPMC10957396 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature

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Overestimation in angular path integration precedes Alzheimer's dementia.

Castegnaro Andrea A Ji Zilong Z Rudzka Katarzyna K Chan Dennis D Burgess Neil N

Current biology : CB 20231011 21

Path integration (PI) is impaired early in Alzheimer's disease (AD) but reflects multiple sub-processes that may be differentially sensitive to AD. To characterize these sub-processes, we developed a novel generative linear-angular model of PI (GLAMPI) to fit the inbound paths of healthy elderly participants performing triangle completion, a popular PI task, in immersive virtual reality with real movement. The model fits seven parameters reflecting the encoding, calculation, and production error ...[more]

PMID: 37827151

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Project description:BackgroundEarly Alzheimer's disease diagnosis is crucial for preventive therapy development. Standard neuropsychological evaluation does not identify clinically normal individuals with brain amyloidosis, the first stage of the pathology, defined as preclinical Alzheimer's disease. Spatial navigation assessment, in particular path integration, appears promising to detect preclinical symptoms, as the medial temporal lobe plays a key role in navigation and is the first cortical region affected by tau pathology.MethodsWe have conducted a cross-sectional study. We related the path integration performance of 102 individuals without dementia, aged over 50, to amyloid and tau pathologies, measured using positron emission tomography. We included 75 clinically normal individuals (19 with brain amyloidosis, 56 without) and 27 individuals with mild cognitive impairment (18 with brain amyloidosis, 9 without). We fitted linear mixed models to predict the path integration performances according to amyloid status or tau pathology in the medial temporal lobal, adjusting for age, gender, cognitive status, education, and video game experience. We decomposed the error into rotation and distance errors.ResultsWe observed that clinically normal adults with brain amyloidosis (preclinical Alzheimer's disease) had spatial navigation deficits when relying only on self-motion cues. However, they were able to use a landmark to reduce their errors. Individuals with mild cognitive impairment had deficits in path integration that did not improve when a landmark was added in the environment. The amyloid status did not influence performance among individuals with mild cognitive impairment. Among all individuals, rotation, but not distance, errors increased with the level of tau pathology in the medial temporal lobe.ConclusionOur results suggest that path integration performance in an environment without external cues allows identifying individuals with preclinical Alzheimer's disease, before overt episodic memory impairment is noticeable. Specifically, we demonstrated that poor angular estimation is an early cognitive marker of tau pathology, whereas distance estimation relates to older ages, not to Alzheimer's disease.Trial registrationEudra-CT 2018-003473-94.

Dataset Information

Overestimation in angular path integration precedes Alzheimer's dementia.

Publications

Overestimation in angular path integration precedes Alzheimer's dementia.

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