COLBOS (COLombia-BOSton) is a collaborative project between the Fundación Universidad de Antioquia, Colombia and Massachusetts General Hospital, Boston. We work with an extraordinary kindred of approximately 5,000 individuals in Antioquia, Colombia, which contains roughly 1,500 carriers of an autosomal-dominant mutation. These carriers are expected to develop early onset Alzheimer’s Disease, with almost 100% certainty, and have a well-characterized disease course, with mild cognitive impairment (MCI) occurring at a mean age of 45, and dementia at 51. We are currently in the longitudinal phase of our study, where we collect both neuroimaging and neuropsychological data from each of our participants about every two years.
The Colombian kindred was first characterized by Dr. Francisco Lopera, a neurologist leading the study at the University of Antioquia in Medellín. MAPP researchers work closely with Dr. Lopera and his team; initial MRI scans and cognitive testing is conducted at his lab before they travelled to MAPP’s location at Mass. General Hospital in Boston for advanced neuroimaging.
The “Paisa” mutation (PSEN1 E280A) that now affects 25 extended families with more than 5,000 members probably arrived in South America more than 3 centuries ago with Spanish conquerors. Dozens of papers have been published about this family, including Dr. Quiroz’s previous research, which found that despite identical behavioral performance, those with the genetic mutations demonstrated brain changes years before symptom onset, compared with non-carrier family members.
Those with the “Paisa” mutation are usually diagnosed with Alzheimer’s disease around their mid-40’s. At MAPP researchers have the opportunity to begin studying brain functions as early as 9 years of age, several decades before clinical symptoms begin. The ability to study brain changes decades before the onset of AD allows researchers to improve the accuracy of biomarkers.
Our work with autosomal dominant Alzheimer’s disease has contributed to the reconceptualization of Alzheimer’s disease as a sequence of physiological changes that begins several decades before symptom onset, and which may be delayed or even prevented. Our group has demonstrated that young adults who carry a mutation in the presenilin-1 gene had brain amyloidosis at the age of 28 year, an average of 17 years before their estimated age of clinical onset (45 years), and had elevated levels of tau pathology in their late 30s, an average of 7 years before symptom onset. Dr. Quiroz’s group was the first one to demonstrate that tau pathology was evident in the brains of carriers of autosomal dominant Alzheimer’s disease, several years before clinical onset (Quiroz et al., JAMA Neurology in 2018).
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