Another problem: as many as 30 percent of people enrolled in Alzheimer's studies based on symptoms didn't actually have the disease -- they had other forms of dementia or even other medical conditions. That doesn't give an accurate picture of whether a potential treatment might help, and the new definition aims to improve patient selection by using brain scans and other tests.

People are questioning a landmark study suggesting that a bacterium involved in gum disease may also cause Alzheimer's. Here's what you need to know about the study The publication of evidence that gum disease bacteria may cause Alzheimer's has prompted questions on social media about how seriously we should take the results. Here's what you need to know about the landmark study. Does the study show that the bacteria cause Alzheimer's disease, or just that the two are linked in some way? Any well-informed reader will know that correlation doesn't mean causation, and not every link between two factors implies that one causes the other.

Kris Kristofferson has been battling memory loss for several years, but his condition has taken a marked turn for the better due to a surprising diagnosis. Doctors have been telling Kristofferson that his worsening memory loss was caused either by Alzheimer's or by dementia that was brought on by blows to the head he suffered in his athletic youth, when he took regular part in rough sports including football, boxing and rugby. The iconic singer-songwriter and actor tells Rolling Stone Country that it got so bad, he sometimes couldn't remember what he was doing from one moment to the next. In typical Kristofferson fashion, he began to write a song about it. "I see an empty chair / Someone was sitting there," the lyrics begin.

Out of the total number, 48 were scans of people with the disease, while 48 were scans of people who suffered from mild cognitive impairment and eventually developed full-blown Alzheimer's. The AI was able to diagnose Alzheimer's 86 percent of the time. More importantly, it was able to detect mild cognitive impairment 84 percent of the time, making it a potentially effective tool for early diagnosis. With more samples and further development, though, the AI could become more accurate until it's reliable enough to be used as a non-invasive early detection system.

IN THE week that the Nobel Prize was deservedly awarded to biologists working on the circadian clock, the importance of their research to life and health has come into even sharper focus. It turns out that regularly failing to get adequate sleep puts us at greater risk of developing Alzheimer's disease. A single night of poor slumber is enough to see damaging effects in the brain (see "Wake-up call: How a lack of sleep can cause Alzheimer's"). This is worrying news for all of us. The cult of busyness now rules, burning the candle at both ends has become a badge of honour.