Blockade of Learning, Memory Genes May Occur Early in Alzheimer’s
A repression of gene activity in the brain appears to be an early event affecting people with Alzheimer’s disease, researchers funded by NIH have found. In mouse models of AD, this epigenetic blockade and its effects on memory were treatable.
“These findings provide a glimpse of the brain shutting down the ability to form new memories gene by gene in Alzheimer’s disease, and offer hope that we may be able to counteract this process,” said Dr. Roderick Corriveau, a program director at NINDS, which helped fund the research.
The study was led by Dr. Li-Huei Tsai, director of the Picower Institute for Learning and Memory at MIT and an investigator at the Howard Hughes Medical Institute. It was published online Feb. 29 in Nature.
Tsai and her team found that a protein called histone deacetylase 2 (HDAC2) accumulates in the brain early in the course of Alzheimer’s disease in mouse models and in people with the disease. HDAC2 is known to tighten up spools of DNA, effectively locking down the genes within and reducing their activity, or expression.
In the mice, the increase in HDAC2 appears to produce a blockade of genes involved in learning and memory. Preventing the build-up of HDAC2 protected the mice from memory loss.
“We think that the blockade of gene expression plays a very important role in the cognitive decline associated with Alzheimer’s disease,” said Tsai. “The good news is that the blockade is potentially reversible.”
Vitamin D Shrinks Fibroid Tumors in Rats
|Fatty fish such as salmon, mackerel and tuna are the best natural sources of vitamin D. Very few foods naturally contain the vitamin. Fortified milk and other fortified foods provide an additional source of vitamin D.
Treatment with vitamin D reduced the size of uterine fibroids in laboratory rats predisposed to developing the benign tumors, reported researchers funded by NIH.
Uterine fibroids are the most common noncancerous tumors in women of childbearing age. Fibroids grow within and around the wall of the uterus. Thirty percent of women 25 to 44 years of age report fibroid-related symptoms such as lower back pain, heavy vaginal bleeding or painful menstrual periods. Uterine fibroids also are associated with infertility and such pregnancy complications as miscarriage or preterm labor. Other than surgical removal of the uterus, there are few treatment options for women experiencing severe fibroid-related symptoms and about 200,000 U.S. women undergo the procedure each year. A recent analysis by NIH scientists estimated that the economic cost of fibroids to the United States, in terms of health care expenses and lost productivity, may exceed $34 billion a year.
Fibroids are three to four times more common in African-American women than in white women. Moreover, African-American women are roughly 10 times more likely to be deficient in vitamin D than are white women. In previous research, the study authors found that vitamin D inhibited the growth of human fibroid cells in laboratory cultures.
“The study results provide a promising new lead in the search for a non-surgical treatment for fibroids that doesn’t affect fertility,” said Dr. Louis De Paolo, chief of the Reproductive Sciences Branch, NICHD, which funded the study. The findings appeared online in the journal Biology of Reproduction.
Fatty fish such as salmon, mackerel and tuna are the best natural sources of the vitamin. Very few foods naturally contain vitamin D. Fortified milk and other fortified foods provide an additional source of the vitamin. Vitamin D is also produced when ultraviolet rays from sunlight strike the skin.
Variation in Brain Development Seen in Infants with Autism
Patterns of brain development in the first 2 years of life are distinct in children who are later diagnosed with autism spectrum disorders (ASDs), according to researchers in a network funded by NIH. The study results show differences in brain structure at 6 months of age, the earliest such structural changes have been recorded in ASDs.
“The difference in the trajectory of brain development between the two groups was dramatic between 6 and 24 months,” said senior author Dr. Joseph Piven of the University of North Carolina, Chapel Hill. “This suggests that the period from 6 to 24 months—when behavioral studies suggest the symptoms of autism are first appearing—is a period of dramatic brain changes in ASDs.”
ASDs involve communication and social difficulties as well as repetitive behavior and restricted interests. Many early behavioral signs of ASDs are not apparent until the first year of age. Typically, ASDs are diagnosed at age 3 or older. According to the Centers for Disease Control and Prevention, ASDs affect 1 of 110 children in the United States.
The study was published online in the American Journal of Psychiatry.