Age-dependent association between cigarette smoking on white matter hyperintensities.

Previous reports have shown that cigarette smoking is associated with white matter hyperintensities (WMHs). However, it remains unclear whether this is true for all ages. We investigated the association between cigarette smoking, WMHs, and age. We retrospectively reviewed charts from 595 patients, who presented as outpatients from January 2007 to March 2010. Grading of periventricular WMHs (PVWMHs) and the scores of deep WMHs (DWMHs) was determined based on criteria established by the Rotterdam Scan Study. We compared the degree of WMHs between smokers and non-smokers, and those younger than the age of 65 years versus those above. In younger age group, smokers had higher grades of PVWMHs and more microbleeds than non-smokers. In the older age group, total burden of DWMHs was much greater in smokers than nonsmokers. Multivariate regression analysis showed that cigarette smoking was an independent risk factor for PVWMHs in the younger age group and for DWMHs in the older age group. The location of WMHs in association with smoking seems to differ among age groups. Age should be considered when interpreting the effects of smoking on the brain.