"Understanding the Anxious Mind" appeared in October in the NYT Magazine. It's a good read, a long, intelligent look at anxiety -- at the physiological responses related to anxiety, at neurological processes related to anxiety, but mostly at the ways nature and nurture combine to cause these disorders.
On the nature side of the equation, the article spends a lot of time looking at experiments by Harvard psychologist Jerome Kagan and others, which study temperament and its role in anxiety among adults:
Jerome Kagan’s “Aha!” moment came with Baby 19. It was 1989, and Kagan...had just begun a major longitudinal study of temperament and its effects. Temperament is a complex, multilayered thing, and for the sake of clarity, Kagan was tracking it along a single dimension: whether babies were easily upset when exposed to new things.... He suspected...that the most edgy infants were more likely to grow up to be inhibited, shy and anxious. Eager to take a peek at the early results, he grabbed the videotapes of the first babies in the study, looking for the irritable behavior he would later call high-reactive.
The article notes that while high-reactive babies are more likely to grow up to be anxious, their temperament doesn't necessarily condemn them to anxiety:
...having all the earmarks of anxiety in the brain does not always translate into a subjective experience of anxiety. “The brain state does not make it a disorder,” Kagan told me. “The brain state exists, and the statement ‘I’m anxious,’ exists, and the correlation is imperfect.” Two people can experience the same level of anxiety, he said, but one who has interesting work to distract her from the jittery feelings might do fine, while another who has just lost his job spends all day at home fretting and might be quicker to reach a point where the thrum becomes overwhelming. It’s all in the context, the interpretation, the ability to divert your attention from the knot in your gut.
Here's where nurture comes into the picture:
Attempts to see what kind of parenting works best with an anxiety-prone temperament leave almost as many questions asked as answered. Which is better for a fearful, high-strung child — a parent who coddles the child and says everything will be all right, or a parent who sets firm, strict limits and has no tolerance for skittishness? You could picture it as going either way, really. On the one hand, it might be good to shield children from the things that worry them. On the other hand, it might be better to urge them, maybe even force them, to confront the things they dread.
The article closes with a look at a fascinating question: Why did anxiety evolve in the first place?
In the modern world, the anxious temperament does offer certain benefits: caution, introspection, the capacity to work alone. These can be adaptive qualities. Kagan has observed that the high-reactives in his sample tend to avoid the traditional hazards of adolescence. Because they are more restrained than their wilder peers, he says, high-reactive kids are less likely to experiment with drugs, to get pregnant or to drive recklessly. They grow up to be the Felix Ungers of the world, he says, clearing a safe, neat path for the Oscar Madisons.