Hippocampal subfield norms built from 34,789 MRI scans and applied to 3,521 patients with five neurological disorders

A team of researchers has built normative reference ranges for the volumes of the hippocampus and its subfields across the human lifespan and used them to map changes in five neurological disorders. The work was published in Nature Communications nature.comNature Communicationsnature.comOpen source ↗. The reference cohort comprised 34,789 healthy individuals aged 4 to 85 years, scanned with 3D T1-weighted magnetic resonance imaging (MRI). The patient group included 3,521 people.

Normative volumes across the lifespan

The hippocampus is a hub of cognition, and its subfields differ in their susceptibility to aging and neurological disorders, the authors note. Modeling the healthy cohort showed that the subfields reach peak volume at different ages, from 27.4 to 40.1 years.

These curves serve as the baseline against which an individual measurement is compared. The comparison is expressed as a centile score, a personalized deviation of a given person's volume from the reference.

Deviations in five disorders

Centile scores were derived for patients with mild cognitive impairment, Alzheimer's disease, Parkinson's disease, cerebral small vessel disease and multiple sclerosis nature.comNature Communicationsnature.comOpen source ↗. According to the authors, the scores captured disease-specific hippocampal abnormalities and supported classification of the diseases.

The scores were also associated with cognitive performance, with longitudinal cognitive outcomes and with disease progression across the disorders. The publication does not give effect sizes or classification accuracy in the summary available here.

The authors also developed a personalized hippocampal health report to facilitate clinical translation. It is intended to present an individual's centile scores and regional volumetric profile to clinicians.

The authors conclude that hippocampal and subfield normative references are useful for personalized diagnosis, cognitive assessment and prognostic evaluation across neurological diseases nature.comNature Communicationsnature.comOpen source ↗. This is a retrospective imaging analysis; the report has been proposed as a tool and the work does not describe it as a validated clinical product.