ADHD Pharmacology

The PFC regulates concentration/sustained attention during boring conditions, shifts attention in multitasking, ignores irrelevent stimuli. In ADHD there is a decreased volume of the PFC.

deficits in motivation, predicting outcomes, completing tasks

attention shifting, working memory, timing, smaller volume in ADHD

Striatum/PFC
Enhances signal
Improves motivation
Improves memory
Improves attention, Focus, Acquisition on info, On-task behavior

PFC
Dampens noise (distractions)
Proper attention shifting
Executive functions
Increased inhibition

25% levoamphetamine salts and 75% dextroamphetamine salts
Dextroamphetamine is a more potent CNS stimulant than levoamphetamine
Used to enhance cognitive/physical performance in non-ADHD individuals
Inhibit DAT, NET, SERT
Potential abuse/addiction

Inhibit DAT and NET.
Little effect on SERT.
Blocks reuptake.
Therapeutic doses have only small effects on dopamine in ventral striatum, thus explaining why therapeutic doses have low abuse potential

Selective NET inhibitor.
Called “non-stimulant” b/c it doesn’t directly increase DA
Not a controlled substance
less effective than the extended-release methylphenidate

Modafinil acts as a weak DA and NE reuptake inhibitor
Indirectly activates orexin and histamine neurons (increased wakefulness/attention)
Less abuse potential?

Some recent evidence suggests modafinil enhances vigilance, working memory, impulse control, sustained attention and other cognitive parameters in healthy controls, but the degree of improvement is likely related to baseline intelligence such that no benefits are observed in the most intelligent cohort.