On 2014 Jun 23, James Lane commented:

James makes an interesting and important point in this article, that withdrawal relief must be considered when assessing the effects of common drugs in habitual users by means of a placebo-control comparison condition. He raises this issue about caffeine research, but it is important as well for studies of nicotine effects in smokers and research into the chronic effects of other drugs in habitual users. More attention should be paid to this problem.

On 2014 Jun 23, James Lane commented:

James makes an interesting and important point in this article, that withdrawal relief must be considered when assessing the effects of common drugs in habitual users by means of a placebo-control comparison condition. He raises this issue about caffeine research, but it is important as well for studies of nicotine effects in smokers and research into the chronic effects of other drugs in habitual users. More attention should be paid to this problem.