The main question being asked in this study is: **How do allostatic load and depressive symptoms relate over time?**
Specific questions being asked in this study are:
* How strongly do allostatic load and depressive symptoms relate cross-sectionally at age 70?
* Does allostatic load at age 70 relate to change in depressive symptoms between ages 70 and 79?
* Do depressive symptoms at age 70 relate to change in allostatic load between ages 70 and 79?
* Between ages 70 and 79, does change in allostatic load correlate with change in depressive symptoms?