Alzheimer's, Dementia treatment, diagnosis: The U.S. Food and Drug Administration has approved a radioactive agent from Lantheus Holdings for use in brain scans to help assess patients for Alzheimer's disease, the company said on Friday. The agent, branded as Tauklarify, is injected before a positron emission tomography, or PET, scan. ‌It makes ⁠abnormal deposits of ⁠tau proteins linked to Alzheimer’s visible in images of the brain in adults with cognitive impairment who are being assessed for the disease.A positive scan does not necessarily confirm ​tau pathology, while a negative scan does not rule it out, the company said. The approval was supported by two studies in which independent readers assessed Tauklarify ​PET scans from more than 500 participants and ⁠classified them as ‌positive or negative for tau pathology.More than 7 million ​people in ​the United States have Alzheimer's, and the number of people ⁠aged 65 or older with the disease could exceed 13 ​million by 2050, Lantheus said.The tau-imaging market is dominated ​by Eli Lilly’s Tauvid, approved in 2020, and is probably worth less than $100 million annually, B. Riley Securities analyst Yuan Zhi told Reuters. Zhi forecasts annual Tauklarify sales of less than $50 million by 2030.Alzheimer's is a progressive brain disease and the most common cause of dementia, gradually damaging memory, thinking and the ‌ability to perform everyday tasks. It is associated with abnormal deposits of beta-amyloid and tau proteins in the brain.Amyloid can ​begin accumulating years ​before symptoms appear, while ⁠the amount and spread of tau are more closely linked to worsening memory and thinking problems.Unlike beta-amyloid imaging agents such as Lantheus’ Neuraceq, the clinical use of ​tau imaging remains limited because there is no approved Alzheimer’s treatment targeting tau, Zhi said.Earlier this month, privately-held Curium agreed to buy Lantheus in a deal valued at up to $8 billion to expand its radiopharmaceutical business. The transaction is expected to close in the first half of 2027.