New York, Feb 27 (IANS): Men who use cocaine at the time of conceiving a child may increase the risk of their sons developing learning disabilities and memory loss, a study has found.

The findings revealed that drug abuse by fathers may negatively impact cognitive development and learning in their male children.

"The results suggest that the sons of male cocaine addicts may be at risk for learning deficits," said R. Christopher Pierce, Professor at the University of Pennsylvania in the US.

In the study, published in the journal Molecular Psychiatry, sons of male rats that consumed cocaine for an extended period of time could not remember the location of items in their surroundings and had impaired synaptic plasticity in hippocampus -- a brain region critical for learning and spatial navigation in humans and rodents.

Further, cocaine use in dads caused epigenetic changes in the brain of their sons, thereby changing the expression of genes important for memory formation. 

D-serine, a molecule essential for memory, was depleted in male rats whose father took cocaine and replenishing the levels of D-serine in the sons' hippocampus improved learning in these animals.

In addition, cocaine abuse in dads also broadly altered the chemical marks on histones -- proteins -- in the brain of their sons, even though the offspring were never exposed to cocaine. 

The authors propose that increased expression of the enzyme, driven by changes in the epigenetic landscape, cause the memory problems in the sons of addicted rats.