Cognitive Enhancement Debate

Zack Lynch posted a video debate about cognitive enhancement on his blog. I just wanted to mention a few of my thoughts on this topic. I think currently a lot of the so called memory improving drugs leave a lot to be desired. I would say that the average person probably would not want to take a drug which caused increased activation of acetylcholine receptors. Dopamine reputake inhibitors can improve concentration and certain aspects of cognition, but they are also not ideal drugs in any way. They can be addictive and may also increase other unwanted traits in the user like stereotypical behaviors. Both transcranial direct current stimulation and transcranial magnetic stimulation have also been used to enhance the capacity of working memory. It's hard to say how relevant this would be for most people, though. Transcranial magnetic stimulation is fairly expensive and might require ongoing use to have any benefit from it. Transcranial direct current stimulation (tDCS) is cheaper and could theoretically be done at home using a portable type device. However tDCS also has less selectivity in its ability to target brain regions, so it is unclear how useful it would be for the average person. Deep brain stimulation seems far too extreme for most people to gain any benefit from.

I think a major problem is how do you define "cognitive enhancement"? The brain is so interconnected that it is hard to affect one cognitive process without tangentially affecting another. You may be able to temporarily improve working memory, but how do you know this doesn't cause worsening on some other type of cognition? Even if you have a good knowledge of the brain, you may not be able to understand all the complex relationships between different brain regions and how they enable specific states of cognition to exist. It could be hard to manipulate things to a desired set point of functioning.

Another problem is that any single drug has the potential to induce massive changes throughout the brain. Even drugs that are rationally designed to be selective are not really all that selective. An SSRI is selective in the sense that it only affects a single transporter (serotonin). However it is non-selective in the sense that there are many serotonin receptors and an SSRI increases serotonin in the synapse thus causing increased activation of all these receptors. Also since you can't disentangle one neurotransmitter system from all the rest, a drug is basically going to change multiple different neurotransmitter systems at the same time. Serotonin regulates the firing of dopaminergic neurons in the ventral tegmental area for instance. SSRI's are of course, not considered cognitive enhancing drugs. However this rule applies to any pharmaceutical drugs that are in the pipeline for "cognitive enhancement".

Even if you use something like transcranial magnetic stimulation to target "selectively" the dorsolateral prefrontal cortex, this area has connections to many other brain regions. Activity in these other areas can be altered even if it is unintended. Also TMS either excites the neurons in the underlying tissue or inhibits their firing. However some neurons being activated may be excitatory, while some neurons being excited may be inhibitory. So your really getting a huge mix of effects that may difficult to really sort out. Some neurons being excited may cause other neurons to decrease their firing rate.

I kind of think that many people looking for cognitive enhancement may be somewhat disappointed currently. There are plenty of more far out technologies like neuromorphic brain implants or brain computer interfaces that could amp up cognitive processes dramatically. However these may be further away. I think most things for enhancing memory or attention now are very blunt tools with undesirable properties and may be of limited value for many.