"It may be that the children have inherited some biological vulnerability to having these structural and functional differences in the brain," Dr. Drevets said.

Some types of depression run in families, suggesting that a biological vulnerability can be inherited.

It results from a complex interplay of biological vulnerability, environmental exposure, and developmental factors (e.g., stage of brain maturity).

In depression, less is known about biological vulnerability, but knowledge is accumulating about other explanations (see chapters 4 and 5).

Since the 1990s, a more neutral view of Tourette's is emerging as a condition involving an interaction between biological vulnerability and adverse environmental events.

Psychological factors, occupational danger, biological vulnerability - all are possible factors in doctors' addictions.

Children and adolescents who use tanning beds are at greater risk because of biological vulnerability to ultraviolet radiation.

Nevertheless, to abandon consideration of primary biological vulnerability to anorexia nervosa would be premature.

Since the 1990s, a more neutral view of Tourette's has emerged, in which biological vulnerability and adverse environmental events are seen to interact.

But children who lose one parent and then have troubled relations with the other may develop a lifelong biological vulnerability to stress.