Science notes: Some fats may harm the brain more

  • Updated: May 26, 2012 - 5:19 PM


Some studies have linked dietary fat to the development of dementia later in life. A new study suggests that the risk may depend on the type of fat consumed.

Scientists led by Harvard's Dr. Olivia I. Okereke studied 6,183 women older than 65, tracking their fat consumption and changes in their mental abilities over four years. The women completed a food questionnaire at the start of the study, then periodically took tests of mental ability.

The researchers assigned a "change score" to each volunteer, summarizing changes in memory and abstract thinking over time -- the lower the score, the greater the decline. The study appeared online in the journal Annals of Neurology.

The researchers reported that they found that women who consumed the most saturated fat were 60 percent more likely than those consuming the least to have change scores that put them below the 10th percentile. On the other hand, women who reported consuming the most monounsaturated fat were 44 percent less likely to have change scores in the lowest one-tenth.


A well-known drug for treating schizophrenia may be a cancer killer, too. In lab studies, the drug wiped out a precursor to leukemia cells without harming normal cells. That means it could give doctors a long-sought way to eliminate every trace of leukemia in patients so that the cancer can never come back.

Even though surgery, chemotherapy and radiation can get rid of a tumor or leukemia cells, the cancer often returns months or years later. One culprit may be so-called cancer stem cells, which give rise to cancer cells. These stem cells resist chemotherapy and radiation, and linger in the body. But cancer stem cells are hard to grow in the lab, so few such drugs have been identified to fight them and none are in clinical use.

Stem cell researcher Mickie Bhatia of McMaster University in Hamilton, Ontario, and his team found that thioridazine, an antipsychotic drug used to treat schizophrenia, blocked the growth of acute myeloid leukemia (AML) stem cells taken from patients. And it knocked down the number of AML stem cells in mice injected with these cells that developed leukemia -- but it spared normal blood stem cells.

When combined with thioridazine, the standard drug used to treat AML was 55 times more potent at killing AML cells in a lab dish than it was alone, Bhatia and colleagues reported in Cell. The study also revealed that thioridazine, which blocks receptors for the neurotransmitter known as dopamine, appears to also work on leukemia stem cells by blocking these receptors. Bhatia says that until now, nobody had noticed that cancer stem cells have dopamine receptors.


Deep-sea microbes living in Pacific Ocean deposits that have remained untouched for 86 million years -- well before dinosaurs went extinct -- consume oxygen in quantities too small to be measured. Until now.

For a study in the journal Science, a team led by Hans Roy, a geomicrobiologist at Aarhus University in Denmark, measured the oxygen concentration in layers of sediment from the sea bottom off Hawaii, 100 feet below the surface. The deepest microbes that they observed used just 0.001 femtomoles of oxygen a day; it would take 10 years for a microbe to consume the amount that a human inhales in a single breath. Said Roy: "The whole community seems to be hovering right at the hunger limit."


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