Our studies on obsessive compulsive disorder (OCD) include genetic studies, genetic epidemiological studies, and studies examining the patterns of obsessive-compulsive symptoms in people with OCD, their family members, and in members of the general population.
Neurocognitive Profiles in OCD
We have evidence from a previous study that individuals with compulsive hoarding, which is related to OCD and in some cases may be a subtype of OCD, have specific changes in neuropsychological profiles compared to individuals without hoarding, including problems with categorization, difficulties with working memory, and problems with attention. We are now extending that study and are investigating whether this profile is also seen in individuals with non-hoarding forms of OCD. This study includes obtaining neuropsychological, EEG-based, and neuroimaging (fMRI) profiles among individuals with non-hoarding OCD, unaffected family members (blood relatives), and healthy controls.
Genetics of OCD
Our genetic studies of OCD include genome-wide association studies (GWAS) in collaboration with the Obsessive Compulsive Foundation Genetics Collaborative (OCFGC), candidate gene studies in nuclear (small) families, and linkage studies in large, extended families from Costa Rica and the US. Genetic linkage analyses on our large families from Costa Rica implicate a region on chromosome 15 which has multiple brain expressed genes, including the ryanodine receptor 3. This region has also been implicated in other human and in mouse studies of compulsivity. We are now in the process of sequencing the entire genome of key individuals in these families, as well as expanding the existing families and collecting additional families to confirm the results.
We have also analyzed a large set of families from the US; these results are also very encouraging. We continue to collect individuals and families with OCD from the US for future studies, which will be needed to confirm any findings from the initial analyses.
Phenomenology and Genetic Epidemiology of OCD
These studies focus primarily on patterns of obsessive compulsive symptoms, both within OCD, and among individuals who may or may not have OCD, such as college or medical students. We have found that OC symptoms are present in relatively predictable patterns in the groups that we have studied, with most individuals having only a few OC symptoms, and a small proportion, including, but not limited to, those with OCD, having many symptoms. Along with others, we have also identified several specific types of OC symptoms, including contamination/cleaning symptoms, hoarding and related symptoms, taboo symptoms (sexual, aggressive and religious symptoms), doubting symptoms (including checking behaviors), and rituals/superstitious behaviors. Although most people with OCD will have many types of symptoms, these specific symptom types do tend to run in families, and may be useful for identifying specific susceptibility genes for OCD.