The Genetics of Compulsive Hoarding
Is compulsive hoarding inherited?
People who compulsively acquire and hoard clutter to the extent that it impairs their daily activities are labeled “compulsive hoarders.” The condition is classed as a subtype of obsessive-compulsive disorder (OCD), present in 30 to 40 percent of individuals affected with OCD. It may damage relationships, cut the individual off from society, and even endanger lives.
Compulsive hoarding is distinct from bad planning and disorganization because it is believed to be a pathological brain disorder. It is often a symptom of other disorders, such as impulse control disorder or attention-deficit hyperactivity disorder. Bereavement or another significant life event can trigger excessive hoarding behavior.
Hoarding often runs in families, but it is uncertain whether DNA is involved. “People with this problem tend to have a first-degree relative who also does,” says Randy O. Frost, Ph.D., a psychologist at Smith College, Northampton, Massachusetts. “So it might be genetic, or it might be a modeling effect.”
Gene research suggests that a region on chromosome 14 may be linked with compulsive hoarding in families with OCD. The study, carried out by a team from Johns Hopkins University School of Medicine in March 2007, analyzed samples from 999 OCD patients in 219 families. Families with two or more hoarding relatives showed a unique pattern on chromosome 14, whereas the other families’ OCD was linked to chromosome 3.
This was the third study to find genetic markers specifically associated with compulsive hoarding, according to Sanjaya Saxena, M.D., director of the University of California, San Diego, Obsessive-Compulsive Disorders Program.
In a letter to the editor of the American Journal of Psychiatry, she writes, “Other studies have confirmed that compulsive hoarding is strongly familial.” This research “adds to the mounting evidence indicating that compulsive hoarding is an etiologically discrete phenotype,” she believes.
What’s more, brain imaging studies suggest that compulsive hoarding involves a specific type of brain activity. Patients have a different pattern of glucose metabolism in the brain than either healthy people or non-hoarding OCD patients.
Hoarding patients have significantly lower activity in the brain’s dorsal anterior cingulate cortex than non-hoarding OCD patients, and a different pattern of cognitive deficits was found, such as more difficulty making decisions and impaired decision-making.
Saxena concludes, “Compulsive hoarding syndrome appears to be a discrete entity, with a characteristic profile of core symptoms that are not strongly correlated with other OCD symptoms, distinct susceptibility genes, and unique neurobiological abnormalities that differ from those in non-hoarding OCD.”
OCD is a common feature of Tourette’s Syndrome, and this can include hoarding behavior, so a further gene study was undertaken by Heping Zhang, Ph.D. of Yale University School of Medicine and colleagues. Looking at the DNA of siblings with Tourette’s, the team found significant links to chromosome 4, 5, and 17.
“Something at chromosome 14 may be associated with hoarding,” says Randy Frost of Smith College. Writing in the Spring 2007 New England Hoarding Consortium Newsletter, he states, “This could be a dramatic breakthrough in our understanding of hoarding.
“However, it is important to note that these studies are all preliminary with relatively small samples that don’t fully represent the range of hoarding in the population. Furthermore, we also don’t yet understand just what traits might be heritable. Perhaps it is something that underlies hoarding, like decision-making problems, and not hoarding itself that is inherited.”
Much larger studies are needed, drawn from the entire population of people who hoard, not just those who are already diagnosed with OCD, he says. Frost is planning a project with experts from Johns Hopkins to answer the question more conclusively.
At present, his advice to people with hoarding tendencies in the family is to be open and honest with their children about the issue. “People who can recognize and talk about their own hoarding problems are much better able to control them than people who can’t.”
David F. Tolin, Ph.D., founder of the Anxiety Disorders Center at The Institute of Living in Hartford, CT, said that “for a condition like compulsive hoarding to come about you probably have to have a person who has a certain set of inherited characteristics. But biology is not destiny. Just because somebody has a genetic predisposition to develop a certain behavioral condition, that doesn’t mean they are doomed.”
Samuels, J. et al. Significant linkage to compulsive hoarding on chromosome 14 in families with obsessive-compulsive disorder: results from the OCD Collaborative Genetics Study. The American Journal of Psychiatry, Vol. 164, March 2007, pp. 493-99.
Saxena, S. Is Compulsive Hoarding a Genetically and Neurobiologically Discrete Syndrome? Implications for Diagnostic Classification. The American Journal of Psychiatry, Vol. 164, March 2007, pp. 380-84.
Saxena, S. et al. Cerebral Glucose Metabolism in Obsessive-Compulsive Hoarding. The American Journal of Psychiatry, Vol. 161, June 2004, pp. 1038-48.
Zhang, H. et al. Genomewide scan of hoarding in sib pairs in which both sibs have Gilles de la Tourette Syndrome. American Journal of Human Genetics, Vol. 70, April 2002, pp. 896-904.
Collingwood, J. (2013). The Genetics of Compulsive Hoarding. Psych Central. Retrieved on April 1, 2015, from http://psychcentral.com/lib/the-genetics-of-compulsive-hoarding/0002465