Behavioural subphenotypes and their anatomic correlates in neurodegenerative disease

Area of Science:

• Neuroscience
• Neurology
• Psychiatry

Background:

• Neurodegenerative disorders present diverse neuropsychiatric symptoms.
• Existing research links specific symptoms or syndromes (e.g., behavioral variant frontotemporal dementia) to brain atrophy patterns.
• Significant symptom heterogeneity and overlap exist across and within dementia subtypes, necessitating investigation into distinct behavioral subphenotypes.

Purpose of the Study:

• To identify shared behavioral profiles in frontotemporal dementia-spectrum and Alzheimer's disease-related syndromes.
• To determine the underlying neural correlates (brain regions) associated with these identified behavioral clusters.
• To investigate if anatomically distinct behavioral subphenotypes exist in neurodegenerative diseases.

Main Methods:

• Principal component analysis (PCA) was applied to behavioral data from 281 patients with seven dementia syndromes, healthy controls, and mild cognitive impairment.
• A 109-item assessment captured the severity of various clinical behaviors.
• Voxel-based morphometry (VBM) was used to correlate behavioral components with regional brain volume loss.

Main Results:

• Seven distinct behavioral components were identified: emotional bluntness, emotional lability/disinhibition, neuroticism, rigidity/impatience, indiscriminate consumption, psychosis, and Geschwind syndrome-related behaviors.
• Each behavioral component correlated with specific patterns of structural brain volume loss.
• These neuroanatomical associations persisted even after controlling for diagnosis, indicating localized neurodegeneration drives these symptom clusters.

Conclusions:

• Distinct behavioral profiles can be identified across various dementia syndromes.
• These behavioral clusters are associated with specific, localized patterns of neurodegeneration.
• Understanding these neuroanatomical-behavioral links may refine diagnostic approaches and inform targeted interventions for neuropsychiatric symptoms in neurodegenerative diseases.