A new study of the brains of rats exposed to lead suggests the metal may contribute to the onset of schizophrenia.

Columbia University’s Mailman School of Public Health researchers found striking similarities in the rat brains to what is known about the brains of human schizophrenia patients.

A description of the study results appear in the journal Translational Psychiatry.

The researchers found that lead had a detrimental effect on cells in three brain areas implicated in schizophrenia: the medial prefrontal cortex, the hippocampus, and the striatum of rats exposed to lead before birth and in the early part of their lives.

Moreover, the density of brain cells declined by approximately one-third — roughly the same percentage decline seen in schizophrenia patients.

Imaging technology also revealed higher levels of a dopamine receptor similar to what has been documented in human schizophrenia patients, and in a previous study of genetically engineered mice.

“The similarities in the brain structure and neuronal systems between what we see in lead-exposed rats and human schizophrenia patients are striking, and adds to a growing body of literature suggesting that early lead exposure primes the brain for schizophrenia later in life,” said senior author Tomás Guilarte, Ph.D.

In a related finding, the researchers found that rats exposed to lead had a much stronger reaction to cocaine than healthy rat controls.

In the experiment, lead-exposed rats that were injected with cocaine ran around in their cages at twice the distance of lead-free control rats. The rat behavior is meaningful because it mirrors what is seen in schizophrenia patients, who are known to have a heightened response to the drug.

Researchers note that schizophrenia is not the only possible consequence of lead exposure. A follow-up experiment will allow the rats to self-administer cocaine in order to test whether lead exposure plays a role in addiction.

“We are currently assessing the impact of lead exposure on both the rewarding and reinforcing properties of addictive drugs like cocaine while exploring the biological underpinnings of how lead exposure plays a role in addiction,” said first author Kirstie Stansfield, Ph.D.

Source: Columbia University’s Mailman School of Public Health