ANNA LYSENKO

Alzheimer’s Disease

Diagnosis

It is very important to understand that a final diagnosis cannot be made until the person is deceased, in a postmortem autopsy report.

The reason for this is that to make a medical diagnosis, a medical examiner needs to be able to identify certain biological markers that are solely identifiable within the disease

these identifiers are mainly amyloid plaque build ups and neurofibrillary tangles which are present in the brain (Allan, Sexton, Welchew & Ebmeier, 2009).

Diagnosis While Alive

While person is still living, you can examine psychological symptoms as well as a few biological markers but they are not unique to AD. The most common ones are total tau protein, phosphorylated tau protein, and amyloid beta 1-42 protein, these proteins are tested and extracted from the cerebrospinal fluid through a procedure called the spinal tap

T-tau and P-tau levels are typically increased while Aβ-42 is decreased in Alzheimer’s patients.

Immunostaining for Confocal Microscopy

Brain sections of control mice are taken and stained with antibodies Ki67, which is an antibody that stains for proliferating cells, and Doublecortin (DCX), which stains for immature neurons, and studied under the Confocal microscope (which uses different fluorescent wave length to fluoresce specimens that were stained by antibodies).

Control mouse

Transgenic mouse

Immunostaining for light microscopy

Brain sections can also be studied under a light

microscope in order to see the plaque build up in mice at

different stages of the disease.

Amyloid plaque build up in a 3 month old transgenic mouse brain

Amyloid plaque build up in hippocampus of a 28 month old transgenic mouse

Neuronal differences

The periventricular zone of the brain as well as the dentate gyrus of the hippocampus show a significant number of proliferating cells as well as immature neurons, with processes that extend throughout the granular layer of the hippocampus. Some cells test positive for both. When it comes to mice which are transgenic the number is significantly decreased.

Mainly in hippocampus, differences in dentate gyrus are insignificant.

Behavioral Tests

Wet mazes are a very common technique in which a mouse is places into a tub of opaque water and is then expected to swim toward an acrylic platform visible slightly above the surface of the water which the mouse must stand on in order to get out of the water.

After a few tries the platform is hidden under the surface of the water but the mouse is eventually able to learn and memorize where it is so that it can stand on it.

Wet Maze