higher, at 4 to 1. What is the prevalence with respect to age? The lifetime prevalence of SAD increases with age until people are in their fifties. After the age of 50 to 54, prevalence rates decline dramatically, and the occurrence of SAD in people over the age of 65 is very low. For More Info Info on this page has been provided by the Canadian Mental Health Association, Ontario Copyright (c) 2004 by the Canadian Mental Health Association, Ontario. This Fact Sheet may not be reproduced without written authorization from CMHA Ontario. Follow Us Donate Polls Yes You! Helping you is important to us. So help us make sure we're giving you the info you need, when you need it. Click here to answer a few questions in this short survey about our Facts & Symptoms section.