I had my first panic attack at the age of 12. I was not depressed at that time, but anxiety definetely affected my mood later.
I agree with Noca that we are a sack of chemicals, and we must sometimes affect those chemical imbalances with chemicals, that is: medication. But at the same time I believe that we are the sum of ouir parts. SA tends to make mood lower due to isolation etc. You can have SA without depression and other way around, but if you don't beat your SA it is likely to have an adverse effect on your mood at some point.
The good thing is that you can beat SA. You may need to take meds, you may benefit of a therapy etc. I personally try to encourage people to to go to the root of the problem and change themselves. We health care people tend to medicalise everything. It sounds so simple: you have problem A, so take these tablets B. I mean, I'm not anti meds. I take meds myself. Not regularly anymore, but as prn(only when I need). But the real turning point for me was when I realised that if my mind has the power of forcing my body to react in a certain unpleasant way, it must logically have the power to force my body to react in another way as well. So, I managed to change the way I react. Basically, I changed myself. It did not happen overnight. And of course it's not all in your mind. If you drink too much coffee for example, you are bound to be anxious. etc. Good diet, exercise everything affects. But the point is that we have so much power in our mind, if we only know how to use it for our benefit, and not against us, as is often the case with anxiety.