Do Stimulants Really Help?
August 25, 2015 at 10:13 PM | categories: mph
Contents
1 Do Stimulants Really Help?
Extensive work examining the effects of stimulants on attentional and executive processes has not found consistent evidence that stimulants enhance or ameliorate these ADHD-related deficits. Although reaction times are significantly reduced, performance on tasks with increased attentional or executive demands is not consistently improved by stimulants [1]. Further, while short-term improvements in academic achievement scores have been demonstrated with stimulant treatment, stimulant medications do not normalize academic achievement in children with attention-deficit/hyperactivity disorder (ADHD), and similarly, although little experimental work has been done, available evidence suggests that deficits in social cognition are not restored with stimulant treatment [1].
In contrast to the extensive work on the effects of stimulants on attention, executive function, and achievement, the potential influence of stimulants on other types of cognition implicated in ADHD (e.g. social cognition and reward sensitivity) is comparably unknown. In one study by Williams [9], several abnormalities during emotional processing could be observed prior to treatment, which were ameliorated with methylphenidate (MPH). In addition, medication significantly improved baseline deficits in the recognition of anger- and fear-related facial expressions. However, the performance of ADHD patients remained impaired relative to healthy controls. Thus, although MPH normalized neural activity, it was associated with only minimal improvement on emotion recognition. This finding is in line with studies that suggest medication results in improvements of inattention and disruptive behavior in children with ADHD, whereas positive social behavior and peer status remain unchanged [8].
Indeed, while small-scale, single-dose studies suggest, overall, that therapeutic doses of MPH ameliorate fronto-executive functions in children and adults diagnosed with ADHD [2, 6, 7], analogous findings in healthy subjects reveal that these effects are not pathognomonic for ADHD [3–5].
Acronyms
- ADHD
- attention-deficit/hyperactivity disorder
- MPH
- methylphenidate
References
[1] L. C. Bidwell, F. J. McClernon, and S. H. Kollins. Cognitive enhancers for the treatment of ADHD. Pharmacol Biochem Behav, 99(2):262–74, Aug 2011. doi: 10.1016/j.pbb.2011.05.002.
[2] S. R. Chamberlain, T. W. Robbins, S. Winder-Rhodes, U. Müller, B. J. Sahakian, A. D. Blackwell, and J. H. Barnett. Translational approaches to frontostriatal dysfunction in attention-deficit/hyperactivity disorder using a computerized neuropsychological battery. Biol Psychiatry, 69(12):1192–203, Jun 2011. doi: 10.1016/j.biopsych.2010.08.019.
[3] R. Elliott, B. J. Sahakian, K. Matthews, A. Bannerjea, J. Rimmer, and T. W. Robbins. Effects of methylphenidate on spatial working memory and planning in healthy young adults. Psychopharmacology (Berl), 131(2): 196–206, May 1997.
[4] H. S. Koelega. Stimulant drugs and vigilance performance: a review. Psychopharmacology (Berl), 111(1):1–16, 1993.
[5] M. A. Mehta, A. M. Owen, B. J. Sahakian, N. Mavaddat, J. D. Pickard, and T. W. Robbins. Methylphenidate enhances working memory by modulating discrete frontal and parietal lobe regions in the human brain. J Neurosci, 20(6):RC65, Mar 2000.
[6] M. A. Mehta, I. M. Goodyer, and B. J. Sahakian. Methylphenidate improves working memory and set-shifting in ad/hd: relationships to baseline memory capacity. J Child Psychol Psychiatry, 45(2):293–305, Feb 2004.
[7] D. C. Turner, A. D. Blackwell, J. H. Dowson, A. McLean, and B. J. Sahakian. Neurocognitive effects of methylphenidate in adult attention-deficit/hyperactivity disorder. Psychopharmacology (Berl), 178 (2-3):286–95, Mar 2005. doi: 10.1007/s00213-_004-_1993-_5.
[8] C. K. Whalen and B. Henker. Social impact of stimulant treatment for hyperactive children. J Learn Disabil, 24(4):231–41, Apr 1991.
[9] J. H. G. Williams. Self-other relations in social development and autism: multiple roles for mirror neurons and other brain bases. Autism Res, 1(2):73–90, Apr 2008. doi: 10.1002/aur.15.