Physical Mental Diagnosis

I have been diagnosed as having anxiety and depression, but I'm wondering, apart from being told you have it by a psychologist, is there any physical way it can be diagnosed?
I'm fairly certain that brain scans and the like don't work for this, but what about some kind of computer analysis/programs? I have seen some kind of computer analysis, where they put electrodes on your head and it shows what parts of the brain light up when different tasks or things are simulated. Doubtful that could show dopamine or serotonin levels but wondering if there's anything similar. I wouldn't mind this done, not just for my depression, but for my behavior/personality as well be honest. Anyway, just thought I'd throw this out there on here, see what thoughts or what people know on this, as I would like some actual proper diagnosis of what's going on with me, so I can try and really identify what's going on. Although anything of this nature wouldn't be available on the NHS (as I'm in the U.K) and would cost a fair bit privately.

I know that certain conditions such as autism and schizophrenia have a physical basis. MRI scans or brain scans have shown that autistic brains are slightly different than neuro-typical brains. And schizophrenia is often due to a chemical imbalance within the brain.
So maybe, if your anxiety and depression have an underlying condition behind them, it could be found by physical means.

Sadly, you'll probably have to wait for the "Brain Map Project" to be completed. I would think something like this might be available, at the very earliest, in 5 years, probably about 10 at the latest. One of the biggest goals of the project is to identify patterns for specific mental health issues, which should make diagnosis easier and much more accurate.

I would like to see something like this for myself: get scanned or a simple test to confirm a physical basis for difficulties that most people don't seem to have. At the very least, I wouldn't be bothered as much by folks who always like to claim "you're making it up just to feel special" or "you're lazy and not trying", etc.

I think brain scans are only now beginning to open up our understanding of the brain's functions with respect to behavioral disorders. You'd think there would be some scan or brain imaging test already that could detect anxious or depressive tendencies, but most appear to be experimental. I did find an article on a USC study using the XBox Kinect attachment that simulates a therapist talking to a patient and responding to facial expressions, agitation, a lack of smiling, etc. The link is here.

Most psychiatrists seem to require the tried and true method of questionnaires and interviews to diagnose patients. As such, computer-based depression detectors tend to be questionnaires, as well.