October 14, 2008
Older men and women often visit their doctors complaining of forgetting an appointment or other slight memory lapses. But medical tests of memory and thinking often come back normal. Are these "senior moments" an early sign of Alzheimer's disease?
For some people, they may be, according to a new study out of the Netherlands. The study, involving 500 people ages 50 to 85, found that people who occasionally forget an appointment or a friend's name may have a loss of brain volume. The findings appeared in Neurology, the medical journal of the American Academy of Neurology.
In the study, participants were asked about occasional memory problems like having trouble thinking of the right word or forgetting things that happened in the last day or two. Others complained of thinking problems, such as having trouble concentrating or thinking more slowly than they used to. None of the study participants had the serious kinds of memory loss typical of Alzheimer's disease. Rather, they had all visited an outpatient medical clinic for reasons like falls, dizziness or headaches.
The participants' brains were scanned to measure the size of the hippocampus, a seahorse-shaped area of the brain important for memory. The hippocampus is one of the first areas damaged by Alzheimer's disease, and as memory problems become more severe, this area of the brain continues to shrink.
Of the 500 people, 453 reported that they had occasional memory or thinking problems. These memory deficits are also referred to as "subjective memory problems," because while individuals say they can notice a problem, they would not show up on regular tests of memory and thinking skills.
The study found that in people with occasional subjective memory problems, the hippocampus was smaller than in people who had no memory problems. However, even if differences in memory are attributable to the size of the hippocampus, this study does not suggest that those with a smaller hippocampus are more likely to get Alzheimer's disease.
"These occasional, subjective memory complaints could be the earliest sign of problems with memory and thinking skills, and we were able to discover that these subjective memory complaints were linked to smaller brain volumes," said study author Dr. Frank-Erik de Leeuw, a neurologist and clinical epidemiologist at Radboud University Nijmegen Medical Centre in the Netherlands. "Because occasional memory lapses were so common, though, much more work needs to be done to use such complaints diagnostically."
All of the participants also had abnormalities in the white matter part of the brain, but these lesions were not correlated with memory lapses.
Other studies have found a link between the size of the hippocampus and brain function. Earlier this year, for example, doctors at Oregon Health & Science University in Portland evaluated the brains of 12 people who had sharp memories and thinking skills at the time of their death. Autopsies revealed that their brains contained large numbers of Alzheimer's plaques, even though they remained mentally sharp and alert. Their brains were compared to those of 23 people who had the same amount of plaques in their brains, but had been diagnosed with Alzheimer's disease before death.
The researchers found that the volume of the hippocampus area of the brain was 20 percent larger in the cognitively intact group compared to the Alzheimer's disease group with dementia. There were no other demographic, clinical or pathological differences between the groups. The results remained the same regardless of whether they were men or women, their age and the total brain volume. [See the story, "A Bigger Brain May Help Protect You From Alzheimer's"]
The findings might help explain why many people remain mentally sharp well into their 80s and beyond, even though autopsies after death show that their brains contain extensive damage like that seen in Alzheimer's disease.
The size of the hippocampus is not necessarily a sign of Alzheimer's disease or impending Alzheimer's. Mild, age-related forgetfulness that is not related to Alzheimer's has also been associated with slightly smaller volumes in certain regions of the hippocampus. What may be more important is that there is evidence that these non-Alzheimer's changes can be reversed by memory exercises and intellectual stimulation.
Experts advise that mentally stimulating activities like completing puzzles, traveling, learning a new language, playing a musical instrument, or doing crossword puzzles can help stimulate new connections between brain cells. These strengthened connections may help to preserve thinking and memory. Maintaining strong social ties and exercising into old age may also help to protect the brain, studies show.
To learn more about keeping the brain fit into old age, visit www.ALZinfo.org, The Alzheimer's Information Site.
A.G.W. van Norden,MD, W.F. Fick, MSc, K.F. de Laat, MD, et al: "Subjective cognitive failures and hippocampal volume in elderly with white matter lesions." Neurology, Volume 71, October 7, 2008, pages 1152-1159.