Case of early onset Alzheimer's disease associated with a novel PSEN1 variant identified in Colombia.

Early-onset Alzheimer's disease (EOAD) is a rare form of dementia that often progresses more quickly than late-onset cases, and is more commonly associated with autosomal dominant mutations. A 47-year-old male presented with progressive cognitive and behavioral decline, a family history of EOAD, and was later found to have a novel pathogenic PSEN1 variant (c.519 G > T, p.Leu173Phe). Initial evaluations, including neuroimaging and laboratory tests, were unremarkable. Neuropsychological testing later revealed memory impairment, executive dysfunction, and neuropsychiatric symptoms. These features, alongside the identified mutation, are consistent with phenotypic presentations of EOAD involving the third transmembrane domain of PSEN1. Pharmacological treatment with cholinesterase inhibitors and antipsychotics yielded limited benefit. Notably, the extended follow-up time, of more than 10 years from the early symptomatic stage, is a unique and valuable feature of this case study, providing rare longitudinal insight into the natural course of genetically confirmed EOAD.