Severe mental disorders such as schizophrenia are perhaps best known for acute behavioral symptoms like hallucination. But Todd Lencz, a genetic researcher and professor at the Feinstein Institute for Medical Research, believes the disease’s lesser known cognitive impairments pose as much, if not more, of a problem for patients.
“Even if you treat the hallucinations, cognitive impact remains,” he said. “It affects the person’s ability to work jobs, go to school and lead a productive and fulfilling life.”
For two decades, Lencz has sought to learn why mental disorders cause a reduction in a patient’s intellectual capacity, and how medical professionals might treat the symptom. He published findings last Tuesday that reveal an answer within the human genome.
Lencz and an international team of 60 scientists, called the Cognitive Genetics Consortium, studied the genes of 35,000 people and discovered new genetic variations that show an overlap between risk for severe psychiatric disorders and reduction in cognitive ability.
“We know hundreds of genetic variations correlated with height and now we have a couple correlated with cognitive ability,” he said. “We have a lot of work to do if we want to understand the molecular basis of brain function.”
But the findings bring scientists a step closer to developing better treatments for mental disorders of the brain such as schizophrenia and attention deficit hyperactivity disorder, according to a statement from the Manhasset-based Feinstein Institute.
The experiment administered a set of cognitive tests to DNA donors to determine their intellectual capacity. Researchers then compared each donor’s test results to a map of his or her genome to find whether particular genetic variations correlated with cognitive ability, Lencz said. The findings were published online in Molecular Psychiatry.
“We’ve been working on this study for eight years,” Lencz said. “At first we worked with 5,000 subjects. It was too small a sample to find significant individual genes related to cognitive ability. Now we have 35,000 subjects.”
Lencz said his goal is to get more than triple the number of DNA donors. By then, he should be able to identify additional genetic variations, also known as genetic loci, correlated with intellectual capacity.
“We have to get to the point of getting at least 100 genetic loci, not just a few,” he said. We know that will take well over 100,000 subjects.”
He said researchers are aiming to have 100,000 DNA donors by the end of 2017.
Though the resulting genetic information could lead to new treatments for mental disorders, it won’t show whether certain genes can make one person more intelligent than another.
“The actual difference in cognitive ability found in the study is statistically significant but minute,” Lencz said. “It doesn’t tell us whether one person is smarter than another.”
