Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia, particularly in those aged 65 and older. Dementia can also occur under age 45, known as young-onset dementia (YOD), although this is rarer. Marchiafava-Bignami disease (MBD) is a rare disorder characterized by demyelination and necrosis of the corpus callosum, primarily affecting individuals with chronic alcohol use. We present the case of a 49-year-old woman admitted for psychiatric and neurological evaluation due to a multidomain cognitive disorder with a sudden onset approximately four years prior, which progressed rapidly, resulting in complete dependence on others for daily activities. Her medical history included moderate depression, chronic alcohol consumption, and professional exhaustion. Psychological assessments revealed severe neurocognitive impairment. MRI scans highlighted significant bilateral parietal atrophy, hippocampal atrophy, and demyelinating lesions in the corpus callosum, consistent with MBD. Despite initial inconsistencies in biomarkers, later tests showed elevated tau protein, phosphorylated tau, and amyloid-beta, supporting an AD diagnosis. Clinical presentation, combined with neuroimaging findings and chronic alcohol consumption history, led to a diagnosis of AD with young onset and chronic MBD. This case illustrates the complexities involved in diagnosing overlapping neurodegenerative disorders. The coexistence of MBD and AD complicates the treatment plan, requiring a multifaceted approach addressing both neurodegenerative and nutritional aspects.