Thursday, August 23, 2012

Review of "Hooked: New Science on How Casual Sex is Affecting our Children."-Chapter 2 (part 1)

Chapter 2 is entitled "Meet the Brain." It purports to educate the lay audience on the inner workings of the brain and how it is involved in sex.

The Good: Neuroscience

The chapter starts out pretty well, praising advances in neuroscience and laying out some basic terminology.  They go through Neurons, Support Cells, and Synapses in a very quick and simplified but reasonably accurate description of their roles in brain function.  Next they discuss Neuroplasticity, though they don't call it that.  Again, fairly accurate and well established science (though much remains to be learned about how malleable the brain is).

However, a number of the citations given for the above information are a bit confusing.  For example, on page 26 they cite a paper in Nature Neuroscience that appears to have nothing to do with the paragraph that references it.   Many of the articles linked seem to be there just as examples of modern neuroscience research without specifically supporting any claim.

The one that really stood out though was this report by The Institute for American Values.  The institute is cited a couple of times through the chapter so I think a brief digression is called for.  The Institute for American Values is another conservative research that is strongly behind "traditional marriage."  The number of iffy sources is increasing.

Still, up to this point (page 30) the chapter has been pretty accurate to neuroscience and current research.  After this though, the quality jumps straight off a cliff.  The remainder of the chapter is filled with myths and baseless speculations that have surrounded neurotransmitters such as oxytocin and dopamine for years.

The Bad: Pseudoscience
Throughout Hooked the authors treat neurotransmitters as standalone causes for whatever they are associated with.  Not only does this vastly oversimplify the complex biochemical network that is the brain, it also leads to grossly misleading intuitive speculations as we will soon see.  Neuroscience is complicated and the tenacity with which the authors jump into the field and start speculating and drawing new conclusions from old evidence is astounding.  I highly recommend this Stanford Lecture on the Neurology of Depression as an example of how wrong our intuitive conclusions about simple causes of complicated effects often is.  The book focuses on three neurotransmitters: Dopamine, Oxytocin, and Vasopressin.

Dopamine is a neurotransmitter that is related to reward and anticipated rewards, providing feelings of enjoyment and reinforcement to certain activities.  While Hooked gets this mostly correct, it is a vast oversimplification to say that dopamine causes feelings of euphoria in response to those activities.  Dopamine plays an important role in a complex reward pathway and also many other functions such as motor control.  Also, interesting research suggests that dopamine neurons also respond to reward prediction.  Some dopamine neurons also seem to respond to negative stimuli or "near miss" phenomenon where the actual experience is not at all pleasurable (i.e. being SO CLOSE to winning a gamble).

All of this should serve to remind us that making broad speculations and intuitive inferences from oversimplifications is a recipe for disaster.  Something seeming logical does not in fact mean it's biological.

With that in mind, let's examine Hooked's claims about dopamine.
"Dopamine is values-neutral...Dopamine will reward for healthy and life-enhancing excitement, but it will also send the reward signal for exhilarating but unhealthy and destructive behavior.

Examples of excitement that dopamine rewards can include the use of nonprescriptive drugs, nonmarital sexual involvement, excessive drinking, dangerous thrill-seeking, and so on."
-Hooked page 34
First of all, dopamine has been implicated in some addiction pathways.  However, recent research also suggests that the connection isn't nearly as clear cut as Hooked makes it out to be.  Jumping from this connection to the claim that all behaviors that release dopamine are addictive is not supported.  For example, some drugs are known as dopamine agonists and bind to dopamine receptors instead of dopamine causing an over-stimulation of the pleasure center.  Drugs like cocaine actually prevent dopamine from being recycled, causing it to flood the brain for about 30 minutes.

Not all dopamine producing activities are created equal.  Grouping drugs, drinking, and dangerous thrill-seeking (which has more to do with dopamine's cousin adrenaline) with sex is misleading.  Eating also releases dopamine, but we don't seem to have any problem enjoying new foods.  In fact, dopamine is released in higher doses with novel experiences.

Also I want to point out a very transparent poisoning of the well here.  Nonmarital sexual involvement is grouped in with drugs, alcohol, and dangerous risks.  Note again that only nonmarital sex is specified, even though marital sex releases just as much dopamine.  If this argument was a valid reason for not having extramarital sex it would be equally valid for marital sex.  As they said before, dopamine is values neutral.  But the authors are clearly not.  Their stance is clear: sex outside marriage is on par morally with drugs abuse and alcoholism.

Interestingly, they also compare extramarital sex to driving too fast:
"...take a heady experience such as driving fast.  The behavior is exciting; it triggers a values-neutral dopamine reward, and strengthens the synapses that lead to making habitually unsafe driving decisions."-Hooked page 35.
What I find interesting about analogizing this to extramarital sex is the stark difference in how the authors propose we deal with the situation  With driving, we teach teenagers how to drive safely.  With sex, the authors want to take away the keys until they find the perfect car and never drive anything else.  We don't ever say "Driving too fast is dangerous, therefore teenagers should be told to not drive at all."

As for what dopamine really does with regards to sex, I recommend another Stanford Lecture starting around 42:30.  There are some really strange and counter-intuitive effects that dopamine has on sexual behavior.  It's not at all simple or straightforward.

One last thing on dopamine and then I promise I'll move on.
"Studies with animals have shown that almost all addictive drugs including alcohol, cocaine, heroine, amphetamines, and even marijuana and nicotine increase dopamine reward signals." 
- Hooked page 34.
I already discussed how all these drugs interact with the reward system in very different ways and it's misleading and incorrect to treat them as all the same phenomena.  But this quote introduces a new problem with uncritically examining research in psychology and neuroscience.  Hooked commits one of the cardinal sins of research by making hasty generalizations from animal studies to human behavior.  This will be a recurring theme so it's important to point out why we shouldn't be too hasty to take animal research as applying to humans.  Consider this analysis of animal studies from Dr. Paul Cunningham, a professor of psychology at River University (emphasis added).
"Subject variables that interfere with drawing animal-human comparisons (extrapolation) are virtually endless and include genetic, biomolecular, metabolic, immunological, cellular, anatomical, physiological, reproductive, circadian, behavioral, cognitive, motivational, and social differences between species. Nonhuman animals are different not only from humans, but also from each other on these variables. Subtle systemic differences in biological organization between species can result in widely divergent responses to the same stimuli.

Most animal species used in psychology experiments are selected on nonscientific grounds (e.g., cost, reproductive capacity, ease of handling, size). Rodents, a favorite species used in psychology drug experiments, sleep 14-15 hours a day, live an average of 2-3 years, produce 8-10 litters a year, are completely colorblind and physically unable to vomit, have a four-day menstrual cycle and sexually mature in four months, possess no tonsils or gall bladder but a liver that regenerates, walk on four legs (quadruped), and have a natural aversion to tobacco, alcohol, and cocaine. Any student of Psychology 101 knows that we cannot automatically generalize results of psychology experiments from one person to another, males to females, infants to elderly, Chinese to Americans, blacks to whites, poor to rich, Rhode Islanders to Californians, or even to the same individual at different stages of the lifespan. The problem is compounded when we want to generalize across species with different genetics and evolutionary histories.
Read More Here
Studies in animals lead to areas of research in humans, not conclusions.  Anyone who treats studies of vole psychology as equivalent to human psychology is making a vast unsupported leap of logic.

I actually thought this was going to be a pretty short chapter after reading it because almost everything in it seemed very plausible and intuitive.  It wasn't until I started reading the literature on the subject that I realized this is probably the most important chapter to tackle.

Looking back on this post it's already getting very long, so I'm going to stop here for now and continue the discussion of chapter 2 in a later post.

Previous: Chapter 1: Let's Talk Sex
Next: Chapter 2: Meet the Brain (Part 2: Oxytocin)
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