The conventional understanding of human intellectual capacity is that it is constant during our life. However, the authors of this article have shown that the statistics, upon which this understanding is based, hide a variation in our teenage years; because some teenagers experience a reduction and some an increase in intellectual capacity, which leaves the population’s average unchanged.
In addition, using structural and functional imaging, they were able to correlate changes in verbal IQ with changes in grey matter density in a region of the brain activated by speech (the left motor cortex), and changes in non-verbal IQ with changes in grey matter density in regions activated by finger movements (the anterior cerebellum).
The timeline of the reported research does not extend far enough to establish whether or not the changes seen in teenagers is temporary; however, my anecdotal evidence suggests that might be the case. I would conclude that the effort used to apply psychological pressure on teenagers to ace examinations might be better expended on piano lessons and piano practice to enhance sensorimotor skills which are strongly correlated to cognitive intelligence – but I suspect many parents have already worked that one out!