Science & Society
Tuneups For Misfiring Neurons
Two different classes of medicine are prescribed for people with ADD/ADHD: stimulants that focus on the dopamine transmitters and nonstimulants that hit the norepinephrine system. But why give a stimulant to someone who is hyperactive?
There are three subtypes of the disorder: hyperactive, inattentive, and a combination of the two. Each version is likely to involve deficiencies in dopamine and norepinephrine activity along the pathways between the basal ganglia and the prefrontal cortext, which control attention and short-term memory. The cells that transport both dopamine and norepinephrine may be working overtime in people with the disorder, sucking up the neurotransmitters that are essential for smooth mental functioning. Some stimulant medications like methylphenidate (Ritalin, Concerta, and Metadate) may slow down that vacuum cleaner and increase the amount of available dopamine. Others, like the amphetamines (Dexedrine, Adderall), simply increase the amount of available dopamine so that even overactive vacuum cells can't suck it all up. And the new nonstimulant medications, like Strattera, act on norepinephrine as Ritalin does on dopamine.
But stimulant medications are tightly restricted because they're considered potential drugs of abuse. Critics contend that these medications have not been well tested on children and could be dangerous, and some even believe that early use of stimulant medications could lead to later substance abuse. On the other hand, there are studies suggesting that unmedicated attention disorders can lead to self-medication and substance abuse. Side effects of the prescription medications--including sleep difficulties, headaches, and tics--while unpleasant, tend to be manageable.
Increasingly, doctors are being urged not to fall into what Thomas Spencer, an ADD expert at Massachusetts General Hospital, describes as the "apologetic model of treatment"--that is, the least amount of the drug over the shortest period of time. Medication for poor attention, he and others contend, is comparable to wearing glasses for poor vision: necessary all the time for nearly every aspect of life.
Biology of Confusion
The reigning theory is that attention deficits are related to faulty biochemical communication in the brain.
1 Normally, a thought or an idea causes a nerve impulse to travel down the axon to the synapse, where it triggers the release of chemical messenger molecules such as dopamine and norepinephrine.
2 These chemicals prompt communication along pathways between the basal ganglia, deep in the brain, and the frontal lobes of the thinking brain.
3 In ADD patients, this all goes askew. Dopamine and norepinephrine are sucked up by vacuum-like molecules, and thus cannot play their usual role in communicating thoughts.
[Drawing labels]
Neuron (2)
Area of detail
Basal ganglia
Prefrontal cortex
Axon
Vesicle sac
Dopamine
Synapse
Vacuumlike molecule
Surface of nearby neutron
Rod Little--USN&WR
-Marianne Szegedy-Maszak
Dazed, Famous
There are many areas in which those with attention deficit disorder are able to focus intensely and bring to bear the creativity and occasional genius associated with their racing brains. These figures show traits of attention disorder.
TERRY BRADSHAW
The former Steelers quarterback has ADHD and has overcome depression, too.
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