Preventitive Medicine
The best offense in health can be a good defense. Preventative medicine includes regular check-ups and health screening.
For anxiety, depression, and cognitive disorders, physicians will often order a battery of laboratory tests along with neuroimaging to search for underlying disorders. Testing may also be for screening and preventative purposes. Some tests which relate directly to supplements discussed on this site include B12, Folate, and DHEA though there are many other tests that might be indicated including thyroid and other hormone levels. In addition to blood work, in my practice I offer routine yearly neuro-cognitive testing for patients over 50. For this I usually use a program known as CNS Vital Signs which can be previewed at www.CNSvitalsigns.com.
Note that even though test results may be within the normal limits, this does not necessarily mean that the results are optimal. Also, if a test is abnormal and you correct by supplementation, physician consultation is still needed to diagnose and treat the underlying cause.