White matter hyperintensity load mediates the relationship between age and cognition

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Gerontology

Background:

• White matter hyperintensities (WMHs) are common in aging and impact brain structure and function.
• Understanding the link between aging, WMHs, and cognitive decline is crucial for identifying at-risk individuals.
• Previous research suggests WMHs may play a role in age-related cognitive changes.

Purpose of the Study:

• To investigate if white matter hyperintensity (WMH) load mediates the relationship between age and cognitive decline.
• To determine if age moderates the association between WMH severity and cognitive performance.
• To explore the relationship between cholesterol levels and WMH severity across different age groups.

Main Methods:

• A cohort of 166 healthy participants aged 20-80 years completed the Montreal Cognitive Assessment (MoCA).
• White matter hyperintensities (WMHs) were manually segmented on FLAIR MRI scans.
• Mediation analysis was performed to assess the indirect effect of age on cognition via WMH load.

Main Results:

• Older age was significantly associated with poorer cognitive function (p < 0.001).
• This association was mediated by WMH load: older individuals had more WMHs, which in turn were linked to lower MoCA scores.
• WMH severity correlated with cognitive decline independently of age, and high cholesterol was associated with increased WMH severity.

Conclusions:

• White matter hyperintensity load significantly mediates the relationship between age and cognitive decline.
• WMH severity impacts cognitive function across the adult lifespan, irrespective of chronological age.
• High cholesterol is a potential risk factor for increased white matter hyperintensities, suggesting a link to brain aging.