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White Matter Hyperintensities and Cognition in Mild Cognitive Impairment and Alzheimer's Disease: A Domain-Specific
Esther van den Berg1, Mirjam I Geerlings2, Geert Jan Biessels3
1Department of Neurology, Erasmus MC University Medical Center, Rotterdam, The Netherlands.
Background:
White matter hyperintensities (WMHs) are related to cognitive dysfunction in the general population. The clinical relevance of WMHs in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) is, however, unclear.
Objective:
This meta-analysis aimed to quantify the association of WMHs and specific cognitive domains in patients with MCI or AD.
Methods:
PubMed (January 1990-January 2017) was searched for studies that used MRI to quantify WMHs, and measured cognitive functioning (≥1 predefined cognitive domain with ≥1 test) in a well-defined population of persons diagnosed with MCI or AD. Fischer's Z was used as the common metric for effect size. Modifying effects of demographics, MMSE, and WMH location were examined.
Results:
Twelve cross-sectional studies on AD (total n = 1,370, median age 75 years) and 10 studies on MCI (9 cross-sectional, 1 longitudinal; total n = 2,286, median age 73 years) were included. The association between WMHs and overall cognition was significantly stronger for MCI (-0.25, -0.36 to -0.14) than for AD (-0.11, -0.14 to -0.08; QM = 10.7, p < 0.05). For both groups, largest effect sizes were found in attention and executive functions (-0.26, -0.36 to -0.15) and processing speed (-0.21, -0.35 to -0.12). No significant modifying effects of age and gender were found.
Conclusion:
WMHs have a medium-sized association with different cognitive functions in patients with MCI and a small, but statistically significant, association with cognition in AD. These result underscore the role of co-occurring vascular brain damage in MCI and AD.
Insights
White matter hyperintensities (WMHs) significantly impact cognition in mild cognitive impairment (MCI) and Alzheimer's disease (AD). WMHs show a medium association with cognitive functions in MCI and a smaller association in AD, underscoring vascular damage's role.
Area of Science:
- Neuroscience
- Radiology
- Gerontology
Background:
- White matter hyperintensities (WMHs) are linked to cognitive decline in the general population.
- The clinical significance of WMHs in Alzheimer's disease (AD) and mild cognitive impairment (MCI) requires further clarification.
Purpose of the Study:
- To quantify the association between white matter hyperintensities (WMHs) and specific cognitive domains in patients diagnosed with MCI or AD.
- To investigate the role of co-occurring vascular brain damage in cognitive dysfunction within these patient groups.
Main Methods:
- A meta-analysis of 12 studies on AD (n=1,370) and 10 studies on MCI (n=2,286) identified through PubMed.
- Studies utilized MRI to quantify WMHs and measured cognitive functioning across predefined domains.
- Fischer's Z was used for effect size calculation, with analyses examining modifying effects of demographics and WMH location.
Main Results:
- WMHs demonstrated a significantly stronger association with overall cognition in MCI patients (effect size -0.25) compared to AD patients (effect size -0.11).
- The largest effect sizes for WMH association with cognition in both groups were observed in attention, executive functions, and processing speed.
- No significant modifying effects of age or gender were identified.
Conclusions:
- White matter hyperintensities (WMHs) exhibit a medium-sized association with cognitive functions in MCI and a small but significant association in AD.
- These findings highlight the importance of considering vascular brain damage in the context of cognitive impairment in MCI and AD patients.