Psychiatric researchers at The Zucker Hillside Hospital campus of The Feinstein Institute for Medical Research have uncovered evidence of a gene that appears to influence intelligence. Working in conjunction with researchers at Harvard Partners Center for Genetics and Genomics in Boston, the Zucker Hillside team examined the genetic blueprints of individuals with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment, and compared them with healthy volunteers. They discovered that the dysbindin-1 gene (DTNBP1), which they previously demonstrated to be associated with schizophrenia, may also be linked to general cognitive ability. The study is published in the May 15 print issue of Human Molecular Genetics, available online today, April 27.
Anil Malhotra, MD, and Katherine Burdick, PhD. (Credit: Adam Cooper, RBP North Shore-LIJ Studios)
"A robust body of evidence suggests that cognitive abilities, particularly intelligence, are significantly influenced by genetic factors. Existing data already suggests that dysbindin may influence cognition," said Katherine Burdick, PhD, the study's primary author. "We looked at several DNA sequence variations within the dysbindin gene and found one of them to be significantly associated with lower general cognitive ability in carriers of the risk variant compared with non-carriers in two independent groups."
The study involved 213 unrelated Caucasian patients with schizophrenia or schizoaffective disorder and 126 unrelated healthy Caucasian volunteers. The researchers measured cognitive performance in all subjects. They then analyzed participants' DNA samples. The researchers specifically examined six DNA sequence variations, also known as single nucleotide polymorphisms (SNPs), in the dysbindin gene and found that one specific pattern of SNPs, known as a haplotype, was associated with general cognitive ability: Cognition was significantly impaired in carriers of the risk variant in both the schizophrenia group and the healthy volunteers as compared with the non-carriers.
"While our data suggests the dysbindin gene influences variation in human cognitive ability and intelligence, it only explained a small proportion of it -- about 3 percent. This supports a model involving multiple genetic and environmental influences on intelligence," said Anil Malhotra, MD, principal investigator of the study.
The specific role of dysbindin in the central nervous system is unknown, but it is highly present in key brain regions linked to cognition, including learning, problem solving, judgment, memory and comprehension. Scientists speculate that dysbindin plays a role in communication between brain cells in these regions and helps promote their survival. An alteration in the genetic blueprint for dysbindin may ultimately interfere with cell communication and fail to protect brain cells from dying, with a resulting negative impact on cognition and intelligence.
The study was funded by grants from the National Institute of Mental Health; National Institute of Child Health and Human Development; NARSAD, The Mental Health Research Foundation (formerly known as National Alliance for Research on Schizophrenia and Depression); and Stanley Medical Research Institute.
Burdick KE, Lencz T, Funke B, Finn CT, Szeszko PR, Kane JM, Kucherlapati R, Malhotra AK. Genetic variation in DTNBP1 influences general cognitive ability. Hum Mol Genet. 2006 May 15;15(10):1563-68. Epub 2006 Jan 13.