A population-based study of head injury, cognitive function and pathological markers

Area of Science:

• Neuroscience
• Neurology
• Gerontology

Background:

• Head injury (HI) with loss of consciousness (LOC) is a potential risk factor for cognitive decline.
• Understanding the long-term impact of HI on brain health and cognitive function is crucial, especially in aging populations.

Purpose of the Study:

• To investigate the association between head injury with loss of consciousness (LOC HI) and later-life cognitive function.
• To explore whether cerebral pathology markers mediate the relationship between LOC HI and cognitive deficits in dementia-free individuals.

Main Methods:

• Utilized data from the 1946 British Birth Cohort (n=502, aged 69-71).
• Assessed cognitive function, Aβ-PET, MRI (brain volume, hippocampal volume, white matter hyperintensities, normal-appearing white matter microstructure), and serum NFL.
• Categorized LOC HI based on timing: >15 years prior to scan or anytime up to age 71.

Main Results:

• Individuals with LOC HI >15 years prior performed worse on cognitive tests, particularly the digit-symbol substitution test (DSST).
• Smaller brain volume (BV) and poorer normal-appearing white matter (NAWM) microstructure explained 30% and 16% of the HI-DSST relationship, respectively.
• No significant association was found between LOC HI and Aβ load, hippocampal volume, white matter hyperintensity volume, AD-related cortical thickness, or serum NFL.

Conclusions:

• LOC HI occurring in mid-life or earlier is associated with lower cognitive function around age 70.
• The observed cognitive deficits appear to be mediated by reduced brain volume and altered white matter microstructure.
• These findings suggest that the impact of LOC HI on cognition is not explained by Alzheimer's disease-related pathology or ongoing neurodegeneration markers.