Increase of hippocampus - chemical versus behavioral

At this post on the use of SSRIs to treat deviant sexual behaviour I came across with the information that after a year of SSRIs use there is an increase of hippocampal volume:

"Furthermore SSRIs have been used in the treatment of PTSD. One study found that after a year of SSRI treatments, subjects with PTSD had a 5% increase in hippocampal volume and a 35% increase in memory function (Bremner, 2006)*. Together, these findings indicate a variety of reasons why SSRIs may be beneficial for offenders with multiple paraphilias." p. 547 (emphasis mine)

There is a study by Eleonor Maguire, et all, that has studied London cab-drivers that have been submitted to "The Knowledge", a rigorous test where they must learn a large number of places and the most direct routes between them, and succeeded.
After comparing them to those who have not studied for this text it was found that London taxi-driver s's hippocampi have increased.

"From existing studies, it is impossible to know whether differences in brain anatomy are predetermined or whether the brain is susceptible to plastic change in response to environmental stimulation. Furthermore, although lesion work (6, 7) and functional neuroimaging work (8) confirm the involvement of the human hippocampus in spatial memory and navigation, there is still debate about its precise role. Given the propensity of lower mammalian/avian hippocampi to undergo structural change in response to behavior requiring spatial memory (2, 3), the present study addressed whether morphological changes could be detected in the healthy human brain associated with extensive experience of spatial navigation. Our prediction was that the hippocampus would be the most likely brain region to show changes."

"Although the hippocampus does not support navigation in isolation from other brain regions, it seems to be crucial to the storage and use of mental maps of our environments. The prolonged accumulation of other types of nonnavigational information may also produce similar hippocampal changes. Our present findings, however, corroborated as they are by the results of patient and neuroimaging studies, suggest that space and the posterior right human hippocampus are intimately linked."

I'm not sure if studies like this are being financed and they are highly important to the long process of trying to understand the brain. I cannot help noticing that the word "suggest" is used leaving it clear that it's not the truth as many of the studies we read like to imply.