Posts tagged parahippocampal gyrus
Articles and news from the latest research reports.
Exercise May be the Best Medicine for Alzheimer’s
New research out of the University of Maryland School of Public Health shows that exercise may improve cognitive function in those at risk for Alzheimer’s by improving the efficiency of brain activity associated with memory. Memory loss leading to Alzheimer’s disease is one of the greatest fears among older Americans. While some memory loss is normal and to be expected as we age, a diagnosis of mild cognitive impairment, or MCI, signals more substantial memory loss and a greater risk for Alzheimer’s, for which there currently is no cure.
The study, led by Dr. J. Carson Smith, assistant professor in the Department of Kinesiology, provides new hope for those diagnosed with MCI. It is the first to show that an exercise intervention with older adults with mild cognitive impairment (average age 78) improved not only memory recall, but also brain function, as measured by functional neuroimaging (via fMRI). The findings are published in the Journal of Alzheimer’s Disease.
“We found that after 12 weeks of being on a moderate exercise program, study participants improved their neural efficiency – basically they were using fewer neural resources to perform the same memory task,” says Dr. Smith. “No study has shown that a drug can do what we showed is possible with exercise.”
Recommended Daily Activity: Good for the Body, Good for the Brain
Two groups of physically inactive older adults (ranging from 60-88 years old) were put on a 12-week exercise program that focused on regular treadmill walking and was guided by a personal trainer. Both groups – one which included adults with MCI and the other with healthy brain function – improved their cardiovascular fitness by about ten percent at the end of the intervention. More notably, both groups also improved their memory performance and showed enhanced neural efficiency while engaged in memory retrieval tasks.
The good news is that these results were achieved with a dose of exercise consistent with the physical activity recommendations for older adults. These guidelines urge moderate intensity exercise (activity that increases your heart rate and makes you sweat, but isn’t so strenuous that you can’t hold a conversation while doing it) on most days for a weekly total of 150 minutes.
Measuring Exercise’s Impact on Brain Health and Memory
One of the first observable symptoms of Alzheimer’s disease is the inability to remember familiar names. Smith and colleagues had study participants identify famous names and measured their brain activation while engaged in correctly recognizing a name – e.g., Frank Sinatra, or other celebrities well known to adults born in the 1930s and 40s. “The task gives us the ability to see what is going on in the brain when there is a correct memory performance,” Smith explains.
Tests and imaging were performed both before and after the 12-week exercise intervention. Brain scans taken after the exercise intervention showed a significant decrease in the intensity of brain activation in eleven brain regions while participants correctly identified famous names. The brain regions with improved efficiency corresponded to those involved in the pathology of Alzheimer’s disease, including the precuneus region, the temporal lobe, and the parahippocampal gyrus.
The exercise intervention was also effective in improving word recall via a “list learning task,” i.e., when people were read a list of 15 words and asked to remember and repeat as many words as possible on five consecutive attempts, and again after a distraction of being given another list of words.
“People with MCI are on a very sharp decline in their memory function, so being able to improve their recall is a very big step in the right direction,” Smith states.
The results of Smith’s study suggest that exercise may reduce the need for over-activation of the brain to correctly remember something. That is encouraging news for those who are looking for something they can do to help preserve brain function.
Dr. Smith has plans for a larger study that would include more participants, including those who are healthy but have a genetic risk for Alzheimer’s, and follow them for a longer time period with exercise in comparison to other types of treatments. He and his team hope to learn more about the impact of exercise on brain function and whether it could delay the onset or progression of Alzheimer’s disease.
Distinctive brain blood flow patterns associated with sexual dysfunction
Premenopausal women who aren’t interested in sex and are unhappy about this reality have distinctive blood flow patterns in their brains in response to explicit videos compared to women with normal sexual function, researchers report.
A study of 16 women – six with normal sexual function and 10 with clear symptoms of dysfunction – showed distinct differences in activation of brain regions involved in making and retrieving memories, and determining how attentive they are to their response to sexual stimuli, researchers report in the journal Fertility and Sterility.
Up to 20 percent of women may have this form of sexual dysfunction, called hypoactive sexual desire disorder, for which there are no proven therapies, said Dr. Michael P. Diamond, Chairman of the Department of Obstetrics and Gynecology at the Medical College of Georgia at Georgia Regents University.
Researchers hope that a clearer understanding of physiological differences in these women will provide novel therapy targets as well as a method to objectively assess therapies, said Diamond, the study’s senior author.
"There are site-specific alterations in blood flow in the brains of individuals with hypoactive sexual disorders versus those with normal sexual function," Diamond said. "This tells me there is a physiologic means of assessing hypoactive sexual desire and that as we move forward with therapeutics, whether it’s counseling or medications, we can look to see whether changes occur in those regions."
Viagra, developed in the 1990s as way to increase the heart rate of sick babies, was approved by the Food and Drug Administration in 1998 to also treat male impotence, a major cause of sexual dysfunction. While several more options for men have been developed since, no FDA-approved options are available for women experiencing hypoactive sexual desire, Diamond said. He notes that a possible critical flaw in developing and evaluating therapies for women may be the inability to objectively measure results, other than with a woman’s self-reporting of its impact on sexual activity.
Years ago, Diamond, a reproductive endocrinologist, became frustrated by the inability to help these women. In fact, many women did not bother discussing the issue with their physicians, possibly because it’s an awkward problem with no clear solutions, he said.
While still at Wayne State University, he and his colleagues began looking for objective measures of a woman’s sexual response, identifying sexually explicit film clips, then using functional magnetic resonance imaging, which measures real-time brain activation in response to a stimulus, to look at responses.
Their latest study links acquired hypoactive sexual desire disorder to a distinct pattern of blood flow in the brain, with significant activation of cortical structures involved in attention and reflection about emotion and mental state. Researchers noted that paying more attention to response to sexual stimuli already is implicated in sexual dysfunction. They also note activation of the anterior cingulate gyrus, an area involved in a broad range of emotions including homeostasis, pain, depression, and apathy. Another key area was the amygdala, which has a central role in processing emotion, learning, and memory.
Women with normal sexual function showed significantly greater activation of areas such as the right thalamus - a sort of relay station for handling sensory and motor input – that also plays a role in sexual arousal. They also experienced activation of the parahippocampal gyrus, involved in making and recalling memories. Interestingly, this area has been found to be more significantly activated in women with surgical menopause receiving hormone therapy.
Diamond notes that the official diagnosis of the sexual disorder requires distress regarding persistent disinterest in sex. Study participants were heterosexual, in stable relationships and had previously viewed sexually explicit images. Those with sexual dysfunction had a mean age of 37 versus 29 in the control group. Part of assessing blood flow patterns included also measuring baseline responses to neutral videos.
Next steps include taking these measurements in a larger number of women and beginning to use brain blood flow patterns to assess therapies, Diamond said.
(Source: eurekalert.org)
University experts spot early signs of Alzheimer’s
Early signs of Alzheimer’s disease can be detected years before diagnosis, according to researchers at Birmingham City University.
The study found that sufferers of a specific type of cognitive impairment have an increased loss of cells in certain parts of the brain, which can be vital in detecting which patients will progress to a diagnosis of Alzheimer’s.
A team of researchers from Birmingham City University (UK), in association with colleagues from Lanzhou University (China) and the Alzheimer’s Disease Neuroimaging Initiative, conducted a brain scan analysis over two years, of patients suffering from amnestic mild cognitive impairment (aMCI) – a condition involving the diminishing of cognitive abilities, from which 80% of patients progress to a diagnosis of Alzheimer’s.
Scans showed that the loss of grey matter in the left hemisphere of the brain was particularly widespread and degenerative for those patients at high risk of developing Alzheimer’s, compared with those with no active neurological disorders.
This region of the brain has been associated with language, decision making, expressing personality, executing movement, planning complex cognitive behaviour and moderating social behaviour.
One of the researchers involved in the study, Professor Mike Jackson, from Birmingham City University, said: “Continuous loss of cells within the regions of the brain highlighted in this study should act as alarm bells for doctors, as they may indicate that the patient is on course to developing Alzheimer’s.”
The brains parahippocampal gyrus, a region which is known to be related to memory encoding and retrieval, was highlighted as an area that should be looked at carefully when examining brain scans to detect early signs of the disease.
Treating Alzheimer’s early is thought to be vital to prevent damage to memory and thinking. Although treatments are available to temporarily ease symptoms, there has been little in the way of success in slowing down the cognitive decline in patients with mild to moderate Alzheimer’s, which has been partly put down to the late timing of the diagnosis.
Experts at Birmingham City University hope that this study will aid other researchers to find an effective clinical treatment to delay the conversion to Alzheimer’s.