Metal Complexes May Help Diagnose Early Alzheimer's Disease

Diagnostic imaging of Alzheimer's disease (AD) among the risk groups can be improved using metal-containing diagnostic agents/radiopharmaceuticals for positron emission tomography (PET), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) imaging as per the research from the Laboratory of Biophysics at NUST MISIS, Lomonosov Moscow State University and D. Mendeleev University of Chemical Technology of Russia, published in the International Journal of Molecular Sciences. Alzheimer's disease (AD) is a neurodegenerative disease that leads to gradual memory loss and behavioral changes. It is characterized by the formation of beta-amyloid plaques and the tau proteins in the brain tissues, 7-15 years before the actual symptoms occur.

Timely diagnostic imaging allows identification of AD and initiating the therapy at an early stage that may delay the progression of the disease. Current PET imaging for amyloid deposits in the brain use special radioactive markers/ PET tracer that is not only expensive but also has a shorter life span.

Metal-containing diagnostical agents such as copper, zinc, and iron cations may deduce the solution to these shortcomings. Thus designing copper-, zinc and iron-based metal complexes prove to bind to amyloids that highlight the amyloid plaques.

Metal Based Diagnosis of Amyloid Deposits

Copper labeled AD diagnostic isotope 64Cu are attractive not only due to the simple and fast introduction of radionuclide at the last stage of non-radioactive synthesis, but also due to its 12-hour half-life, perfect for PET imaging. Gallium-68 (68Ga) is another promising PET radionuclide with a half-life of 271 days.

These metal-containing agents hold beneficial for single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) too. However, the presence of the blood-brain barrier (BBB) limits the AD imaging agents from reaching the cerebral target.

The BBB is a highly selective functional barrier mechanism of the brain that controls the passage of substances from the blood into the brain. It also serves as a clearance path for waste metabolites of the brain.

64Cu, 68Ga, and 99mTc (technetium-99 m) are some of the metal-based agents that can cross the BBB and bind with amyloid in the brain and with a longer life-span.

The copper-based coordination compounds for PET imaging, gallium-based coordination compounds for MRI, and technetium -based coordination compounds for SPECT imaging showed the most promising results among the various other compounds.

Source-Medindia