Gross Neuroanatomical Changes

In the late stages of the disease, brains from patients with AD will appear grossly atrophied and decreased in weight. Widening of the sulci and ventricles is observed.

Brain of a patient with Alzheimer's disease. Notice the prominent atrophy of the cerebral cortex and the widened sulci indicated by the arrow.

Brain of a patient with Alzheimer's disease. Notice the enlarged ventricles indicated by the arrow.

This pathology is indicative of the massive cell death that occurs during the course of the disease.

The cortex and the hippocampus are the primary brain areas involved in memory and learning. Hippocampal dysfunction is observed early in the course of AD. Some of the functions of the hippocampus are shown below.

1. Semantic memory: memory of facts and concepts

2. Episodic memory: permits conscious recollection of events and the relations between them

3. Spatial memory: involves spatial orientation and recognition

As the disease progresses, the temporal lobe functioning is also affected. The temporal lobes govern much of the activity needed for complex learning and thought. Frontal cortex involvement may be linked to the onset of behavioral symptoms. The primary motor cortex (parietal lobe) and the visual cortex (occipital lobe) are not generally affected until late stage progression.