SIDS and Serotonin, Cry-It-Out and Cortisol

A few weeks ago a study in the Journal of the American Medical Association said researchers found low levels of serotonin (and the enzyme needed to make serotonin) in babies who died from SIDS (sudden infant death syndrome). Serotonin acts as a neurotransmitter, regulating sleep, breathing, heart rate, body temperature, mood, appetite, muscle contraction and memory.
This news immediately made me think of the studies that show how leaving babies to cry-it-out alone raises their cortisol levels. (Cortisol is a stress hormone.) I was curious how serotonin levels and cortisol levels were related. Were they inversely related? Now I'm not implying that crying it out kills babies, I am just curious as to whether leaving a baby with this "fundamental abnormality" to cry it out alone could add to the risk of death.
Many studies link serotonin imbalances with depression. When we're stressed our bodies release the hormone cortisol. Among other things, cortisol stimulates hepatic detoxification through inducing tryptophan oxygenase (to reduce serotonin levels in the brain).

The fact that patients with major depression exhibit decreased brain serotonin (5-hydroxytryptamine, 5-HT) function and elevated cortisol secretion has reached the status of textbook truism. More recent formulations have suggested that elevated cortisol levels, probably caused by stressful life events, may themselves lower brain 5-HT function and this in turn leads to the manifestation of the depressive state (see Dinan, 1994). This elegant proposal neatly ties abnormalities of cortisol secretion and 5-HT function into a causal chain in which cortisol is the key bio- logical mediator through which life stress lowers brain 5-HT function, thereby causing depression in vulnerable individuals.

- P.J. Cowan, British Journal of Psychiarty 2002, 180, 99-100.

Could these findings apply to babies instead of depressed adults? I would think babies count as "vulnerable individuals" and babies with a genetic abnormality affecting their serotonin production would definitely be vulnerable.
I've also read in numerous places that having a baby sleep in the same room as its parents can help the child to regulate its breathing - subconsciously imitating parental breathing patterns. (Although I'm not sure how this would work if a parent has sleep apnea or something.)
I've always been an advocate of nighttime parenting through safe bed-sharing practices, but your baby doesn't even have to been in the bed with you to reap the benefits of your breathing patterns. Until a test is established to check for this genetic serotonin abnormality, I would suggest all parents pull the baby's crib into their room and never let them cry-it-out alone. Not to mention that crying it out teaches your baby not to trust you and tells them that you aren't responsive to their needs. Crying is the only way they know how to communicate. (If a baby is crying a lot, but being held, the cortisol-production response is not the same. A crying held baby doesn't equal a stressed baby, but crying alone baby does.) Always make sure your baby is sleeping on their back, has no pillows, toys or bedding near their head and isn't over-bundled.

(Photo by me of my son sleeping on his daddy when he was very tiny and new.)