After memory starts to decline in people with a pre-Alzheimer's condition, "executive functions" such as concentration, decision-making and problem-solving may be the next brain functions hit, a new study suggests.

"If someone with mild cognitive impairment starts having trouble staying on task, concentrating, multitasking, making decisions or paying attention to several things at once, that would mean they are progressing toward dementia," said Dr. Ron Petersen of the Mayo Clinic in Rochester, Minn., who led the study.

Alzheimer's disease is a progressive, degenerative disease that destroys vital brain cells.
(CBC)

Knowing what cognitive functions are likely to become impaired could help patients and their families keep an eye out for a worsening condition, he added in a release on Monday. 

Doctors consider someone has moved from mild cognitive impairment to Alzheimer's when memory and one other aspect of brain function, such as concentration, is affected.

Petersen's team looked at 354 people with mild cognitive impairment who were followed for an average of three years to track systematically how the condition progresses.

Patients were checked for impairment in executive function, language and sensing how objects relate to each other, such as jigsaw puzzle pieces.

Early in mild cognitive impairment, the participants' abilities to pay attention began to diminish, the researchers reported at an international conference on Alzheimer's disease and related disorders in Madrid, Spain.

By measuring if executive function has weakened, future studies could determine if a drug is helping to slow or stop the disease, the researchers said.