Which disease reduces bone density and causes the bones to becime brittle

osteoporosis

explanation:

Osteoporosis, or porous bone, is a disease defined by low bone mass and skeletal degeneration of bone tissue, starting to bone brittleness and an enhanced chance of breakages of the hip, spine, and wrist. Men, as well as women, are influenced by osteoporosis, a disease that can be anticipated and handled. In the United States, more than 53 million people either previously have osteoporosis or are at great risk due to weak bone mass.

answer; planning ahead;