Dear David, depending on the type of mental disorder, the chronicity and the type of physiological disorder, it is often difficult to assess whether specific symptoms are related to mood disorder, or the physiological disorder, so I understand the dilemna. Amother difficulty is that of timing tests to coincide with the possible onset, or remission of a disorder, such as Dysthmic Depression. Self report tests, such as the BDI - II, the SC - 90, in conjunction with interviews (such as the SCID) seem at the moment to be the best combination of tools. Currently I am considering the possible use of tests based on cognitive processes, which are short and can be re-administered a number of times. On a correlational basis these cognitive processes are often linked to an improvement in symptomology of modd disorders. It may provide another method of assessment. The difficulty for instance with somatic complaints, is that mood disorders may magnify them, whilst in some cases there are physiological pathways that are shared between physiological disorders and mood disorders. The other difficulty one has, is that patients do become test wise and often anticipate and attempt to answer questions according to their own personal goals. However some tests do seem to have this type of problem built into the analysis of results and this may be of use. I hope that this has been useful. Your question is a very important one!

Thank you Cheryl for that very helpful response to my question. It is encouraging to see that researchers such as yourself are exploring the use of more precisely assessed cognitive functions which may provide independent validation of both self-reported symptoms and structured interviews such as the SCID, which itself is based on the diagnostic criteria embedded in the current version of the Diagnostic and Statistical Manual updated and published periodically by the Amer Psychiatric Assoc.

While I look forward to learning more about the specific cognitive measures you are studying as independent markers of depression, the study that I have been involved in for the past 30 years is the Multicenter AIDS Cohort Study, the MACS, which has defined the natural and treated history of HIV infection in a diverse sample of gay/bisexual and MSM. And an early recognized effect of HIV infection has been the ability of some variants of HIV-1 to invade the brain and cause progressive cognitive deficiency even in the presence of effective anti-retroviral therapy that halts the progression of HIV-related immune deficiency. So, there is no reason to belief that cognitive markers of depression validated in non HIV infected persons are valid in persons with mild to severe HIV-related cognitive deficiency. In fact, some HIV+ men and women who develope moderate to severe cognitive deficiency display what I would label as classical "pseudo-depression," or anergic depression-like symptoms with prominent slowing of cognitive processes typical of organic brain damage.

That is very interesting indeed! This could be related to another conversation I am involved in whereby MDD and treatment resistant Depression could be a form of neuroprogressive disorder. If you are looking at cognitive deficits, they are often considered as an independent syndrome, separate from symtomology and cognitive processing. There has been much discussion on the possibility that deficits (which naturally have a physiological basis) and appear to not improve after recovery from for instance MDD, or Scizophrenia etc, may occur across all disorders on a continuum, and in different straengths and combinations. Neuropsychological tests would most likely be the best way to test for deficits, with a combination of tests which assess symptomologies and actual cognitive processing. Not sure if this helps..

Sorry, the most sensitive tests for cognitive deficits are neuropsychological ones, and there are different batteries which measure different deficits.