Normal vs Alzheimer's Disease (IMAGE) Radiological Society of North America Caption Primary pathophysiology of AD. The two primary lesions associated with AD are extracellular nonvascular aggregates of Aβ (senile plaques) and intraneuronal protein inclusions secondary to aggregation of misfolded and abnormally phosphorylated protein τ (neurofibrillary tangles). Credit Radiological Society of North America Usage Restrictions May use with credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.