"It could be that all of the chemo drugs cross into the brain after all, or that they act via peripheral mechanisms, such as inflammation, that could open up the blood-brain barrier," Gross said.
"Neurogenesis can also be altered by stress, sleep deprivation and depression, all of which are common among cancer patients," added Janelsins. "More thorough studies are needed to understand the interplay of these factors and the long-term effects of chemotherapy on the brain."
Researchers conducted a second study of a single high dose of cyclophosphamide, a mainstay of adjuvant chemotherapy for breast cancer, because chemo-brain is a frequent complaint of people receiving this drug. The single high dose resulted in a 40.9 percent reduction in newly divided brain cells, the study said.
In previous studies the experimental growth hormone IGF-1 had demonstrated that it could generally promote new brain cell development within the central nervous system. Thus, investigators chose to test its effect in the animal model.
They administered IGF-1 prior to and following a conventional cyclophosphamide multiple-dose regimen, and a single, high-dose of cyclophosphamide. The IGF-1 seemed to increase the number of new brain cells in both models, but was more effective in the high-dose model, the study concluded.
The research team plans to conduct additional studies which will allow them to further test the impact of IGF-1 and other related interventions on the molecular and behavioral consequences of chemotherapy.
Source: University of Rochester Medical Center