FRIDAY, July 29 (HealthDay News) -- Any time there's a violent tragedy -- the killing of at least 86 people at a youth camp in Norway, the shootings of a congresswoman and others in Tucson, the Virginia Tech massacre -- one question seems to ring clearer than others: Why didn't someone notice beforehand that the suspect might be disturbed and capable of committing deadly violence?

(HealthDay News) -- Mealtime with an Alzheimer's patient can be stressful and challenging, to make sure the patient gets sufficient nutrition.

(HealthDay News) -- Obstructive sleep apnea commonly occurs when swollen tonsils or adenoids obstruct the airways during sleep.

FRIDAY, July 29 (HealthDay News) -- Addiction to prescription drugs is common among patients with chronic pain, with 35 percent of patients receiving long-term treatment with opioids now meeting the criteria for addiction, a new study has found.

FRIDAY, July 29 (HealthDay News) -- A growing number of young American adults are engaging in what's called "stayover relationships," in which they spend three or more nights together each week while still having the option of going to their own homes, a new study shows.

FRIDAY, July 29 (HealthDay News) -- Low blood pressure while undergoing dialysis puts patients at increased risk for clots where their blood vessels are connected to the dialysis machine, a new study says.

FRIDAY, July 29 (HealthDay News) -- Excluding children from discussions about their hospital care can make them feel scared and angry, a new study finds.

FRIDAY, July 29 (HealthDay News) -- An epilepsy gene, called LGI2, has been found in Lagotto Romagnolos -- a specific breed of dog known for truffle hunting, according to a new study.

FRIDAY, July 29 (HealthDay News) -- Some ethnic groups are more likely than others to store dangerous fat around their internal organs as they gain weight, according to a new study.

FRIDAY, July 29 (HealthDay News) -- The brains of two of four former Canadian Football League players showed signs of a brain disease associated with concussions, say researchers with the Canadian Sports Concussion Project.

FRIDAY, July 29 (HealthDay News) -- Teenage girls who develop post-traumatic stress disorder after being sexually assaulted aren't at increased risk for binge drinking, new research shows.

THURSDAY, July 28 (HealthDay News) -- Women who took the cancer-suppressing drug tamoxifen for five years after a breast cancer diagnosis were nearly 40 percent less likely to have the cancer return, and that protection lasted for more than a decade after they stopped taking the drug, a new study finds.

FRIDAY, July 29 (HealthDay News) -- Developed countries have seen a drop in breast cancer death rates in recent years, but a new international study suggests this trend is less about rising screening rates and more about the availability of increasingly effective treatments and improving health-care systems.

Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

FRIDAY, July 29 (HealthDay News) -- The U.S. Food and Drug Administration should scrap the system it uses to approve and regulate "moderate-risk" medical devices such as artificial joints and heart pacemakers, according to a highly anticipated federal report released Friday.