WASHINGTON (Reuters) - Diabetes can slow the brain, causing trouble with two types of mental processing in adults of all ages, Canadian researchers reported on Wednesday.

Healthy adults did significantly better than diabetics on two tests of mental functioning — executive functioning and speed of response, the team at the University of Alberta found.

"Speed and executive functioning are thought to be among the major components of cognitive health," Roger Dixon, who worked on the study, said in a statement.

Executive functioning includes the ability to focus, work with new information to solve problems and to give thoughtful answers to questions.

Writing in the journal Neuropsychology, the researchers said they studied 41 adults aged 53 to 90 with type-2 diabetes and 424 adults in good health.

There were few differences between adults under and over the age of 70, which suggests the changes occur early, Dixon said.

"There could be some ways to compensate for these declines, at least early and with proper management," he said.

Diabetes is known to raise the risk of diseases such as Alzheimer's. The high blood sugar levels caused by the condition can damage both blood vessels and nerves and lead to damage in many organs.

A study published in July showed that diabetics who take insulin plus a diabetes pill have a lower risk of developing Alzheimer's disease than diabetics who take insulin alone.

At least 194 million people worldwide have diabetes, and the World Health Organization expects the number to rise to more than 300 million by 2025.

Most have type 2 diabetes, formerly called adult-onset diabetes, in which insulin production decreases or the body becomes less able to use it. Diet and exercise can control the condition and there are several different classes of drug on the market to treat it.