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Abstract
Objective: We aimed to quantify the effects of white matter hyperintensities (WMHs) on specific cognitive functions with particular attention to WMH progression and localization.
Methods: PubMed (January 1990–July 2013) and bibliographies from included articles were used. Studies that were included (1) used MRI; (2) had a population-based or case-control design with a healthy control group that could be used for analysis; (3) matched/adjusted for age, sex, and education; and (4) addressed ≥1 predefined cognitive domains with ≥1 validated neuropsychological tests. Data were independently extracted by 2 investigators. Pearson r was extracted/calculated and used as the common metric for the effect size across studies.
Results: Twenty-three cross-sectional and 14 longitudinal studies were included with a total of 8,685 and 7,731 participants. Presence of WMHs was significantly associated with concurrent cognitive deficits in all examined domains: general intelligence (Fisher z −0.10, 95% confidence interval [CI] −0.19 to −0.04), memory (−0.08, −0.13 to −0.06), processing speed (−0.11, −0.17 to −0.07), attention and executive functions (−0.11, −0.16 to −0.07), and perception/construction (−0.15, −0.21 to −0.07). Similar effect sizes were observed for cognitive decline over time. WMH progression was associated with greater cognitive decline, particularly for general intelligence (Fisher z −0.31, 95% CI −0.5 to −0.02) and attention and executive functions (−0.32, −0.34 to −0.28).
Conclusions: The small but robust and consistent effects of WMHs on all cognitive domains suggest a more global effect on cognition than previously thought. Progression of WMHs was associated with even worse cognitive functioning, most pronounced in attention and executive functioning.
GLOSSARY
- CI=
- confidence interval;
- WMH=
- white matter hyperintensity
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received November 19, 2013.
- Accepted in final form March 18, 2014.
- © 2014 American Academy of Neurology
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