If severe brain loss occurs before age 60, then it is usually due to drug abuse, poor circulation, viruses, and genes, not the result of normal aging. Thus, this is disease connected or:
Deductive
Vocational
Metabolic
Pathological

There are a number of diseases and disorders that occurs inside the human body, which are mainly due to the drug abuse, and the resulting affects of the drug abuse like having a less developed circulation system and disorders inside its genetic sequence.These disorders may occur before the age of 60, as there are less chances for the individuals who suffers from such diseases and disorders, as this is connected or are Pathological in nature.Just because the whole situation is been created by the actions of the individuals inside a given time frame, as there are a number of reasons for having a poor blood circulation system inside the human body.Like it can be due to excessive smoking, or over dose of drugs by the person which can also lead to severe brain loss before the age of 60.

The right answer is b hydrogen bonds!