Brain Scanning and Depression: Strange Days.
What is the current situation for understanding depression with brain scanning? The issue is cloudy, and with the paradox that certain treatments by means of brain scanning technology have preceeded the understanding of brain structure and processing -- which, of course, is just what brain scanning was supposed to accomplish before methods of treatment were ever determined. Things are not going as planned.
Consider, for example, Transcranial Magnetic Stimulation. This is a newly discovered, though experimental method of treatment for people diagnosed with manic depressive disorder. The effects appeared to be short term, at least when this method was applied on a frequency of about one to two times per week ("Magnetic Therapy", 2006)
The treatment technique was earlier and accidently noted when researchers observed a correlation between patients self-reporting diminished feelings of depression after their receiving regularly scheduled MRI scanning. The the original MRI technique yeilding this phenomena of improvement for depression symptoms was ecoplanar magnetic resonance spectralscopic imaging , or EP-MRSI ("MRI Scans", 2005).
Later follow-up studies had confirmed similar responses in laboratory rats. These gave additional support to the observations made in human treatment contexts. The animal study was a follow-up to check that that electromagnetic fields could indeed affect brain biology. William Carlcon, the director of Harvard's Mclean's behavioral genetics laboratory, notes that, "we found that when we administered the magnetic stimulation to the rats, we saw an anti-depressant like effect, the same effect as seen after administration of standard anti-depressant drugs" ("MRI Scans", 2005).
There is a certain irony in that MRI imaging has had a positive correlation with treating depression in human beings, when the high hopes for brain imaging systems have not returned the hard science that researchers suspected it would during the rise of such technologies in the 1990s. Published imaging studies appear of a rate of around 500 a year, but have not been effective for understanding the root causes of depression in the brain (Carey, 2005).
I argue that this because brain scanning presents both correlation and causation challenges. It is not clear, for example, whether depression brings about a change in brain structure, or whether particular brain structures cause depression. Moreover, there are significant variations in gross brain structure among people, and also in the processing areas where particular types (or groupings of types) of mental states occur. However, the technology curve is promising, with MRI scanning technology roughly following well-tracked computational power increases, which double around every 20 or so months.
Carey, Benedict "Can Brain Scans see depression" October 18, 2005
"MRI scans may have antidepressant effect: Study suggests electromagnetic fields can affect brain biology" March 10, 2005
"Magnetic Therapy May Help Control Depression: Brain Stimulation Can Improve Symptoms Small Study Finds" January 30, 2006. http://www.msnbc.msn.com/id/11100427/