About 30% of cancer patients who receive chemotherapy later suffer from so-called chemo brain, a condition characterized by memory loss, attention deficits, and decreased problem-solving abilities. Scientists know little about how anticancer drugs lead to this cognitive decline. But a new study reports that treating rats with the drug carboplatin impairs the release of dopamine and serotonin, which are neurotransmitters that play key roles in many cognitive functions affected by chemo brain (ACS Chem. Neurosci. 2016, DOI: 10.1021/acschemneuro.5b00029). Michael A. Johnsonof the University of Kansas and colleagues observed that rats receiving carboplatin injections for four weeks performed slightly worse in a test of spatial memory than did animals receiving just saline solution. When the team studied brain slices from the carboplatin-treated rats, they found that dopamine and serotonin release had decreased by 42% and 55%, respectively, compared with slices from the animals getting saline. However, the total amount of dopamine and serotonin within neurons did not differ, suggesting that carboplatin treatment didn’t alter production of the neurotransmitters but instead affected the ability to release the neurotransmitters into synapses, Johnson says.