Does aging heavily impact cognitive function?

In our study, we wanted to see if we could predict how fast our brain ages or how fast our cognitive function can decline because age is a major risk factor for cognitive aging and we all have decreases in cognitive function as we age. Cognitive function entails concentration, focusing on tasks, remembering events and words, and also executive functions i.e. making decisions in everyday life. So we wanted to find out what has already been studied about cognitive aging in people with depression