RT Journal Article SR Electronic T1 Marriage and risk of dementia: systematic review and meta-analysis of observational studies JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP jnnp-2017-317178 DO 10.1136/jnnp-2017-317178 A1 Christopher P L H Chen A1 Vincent C T Mok YR 2017 UL http://jnnp.bmj.com/content/early/2017/10/30/jnnp-2017-317178.abstract AB