If you study depression and anxiety (in the U.S.), you find that they are correlated to a shockingly high degree (e.g., in one of my studies, when I correlated PHQ-9 depression scale scores with GAD-7 anxiety scale scores, I found that r = 0.82 ).
Additionally, many studies have found that SSRIs (and other medications) help people with both depression and anxiety, as do certain therapeutic modalities such as Cognitive Behavioral Therapy, suggesting further linkage.
Findings like these lead some to conclude that the two diseases are just one and the same, or part of the “same thing.” I don’t agree. The main reasons I don’t agree are because:
A. Anxiety and depression feel different internally (i.e., they have different “qualia” for most people). This is a major part of how we can tell which one we’re experiencing at a given moment. For instance, for me, I am more likely to experience anxious feelings in my upper chest, with depressive feelings being more like an “emptiness.”
B. Some events cause anxiety but not depression (e.g., worrying that there is a tiger hiding by the watering hole because you saw a tiger there at another time); others cause depression but without necessarily causing anxiety (e.g., having trouble getting over the death of a beloved friend a year after the event).
C. The behavioral changes they cause tend to be different since anxiety tends to cause avoidance of the things you fear, whereas depression tends to produce a lack of motivation.
D. There are some personal factors that are strongly linked to one but not the other. For instance, in our research, we found that negative self-talk is strongly linked to depression, but it is not linked to anxiety (once you control for depression).
Clearly, though, anxiety and depression ARE very connected.
So, how ARE they linked?
Here’s what I think the main links between anxiety and depression are:
1. Anxiety sometimes causes depression since anxiety at high levels leads people to avoid important things of value out of fear and (in some cases) out of exhaustion. Missing out on the things they value has a tendency to make people depressed. And feeling trapped by your anxiety can also give a sense of hopelessness, leading to depression.
2. Depression sometimes causes anxiety since feeling that “nothing really matters,” or that there is “no point in trying,” or that “I’m worthless” can lead to difficulty with motivation, exhaustion, and giving up, which can cause a snowballing set of anxiety-inducing life problems (e.g., fear of losing one’s job, or fear of losing friendships, or a piling up of life chores that go undone, with increasingly large consequences).
3. There are factors that increase one’s chances of getting both depression AND anxiety, such as early life trauma, negative life events (like losing a job), and poverty.
Therefore I see the links this way:
Depression sometimes causes anxiety.
so: D -> A
Anxiety sometimes causes depression.
so: A -> D
A negative spiral can occur, with anxiety causing depression, which causes anxiety, which causes depression, and so on, in a feedback loop.
so: A -> D -> A -> D -> …
And difficult life situations and events can cause BOTH simultaneously.
so: X, Y, Z -> A & D
So yes, depression and anxiety are highly related, but they don’t, by any means, seem to be “the same thing.”
This piece was first written on January 10, 2021, and first appeared on this site on December 23, 2022.
Comments