INCREASED NUMBERS OF BETA-APP-IMMUNOREACTIVE NEURONS IN THE ENTORHINAL CORTEX AFTER HEAD-INJURY

IN a previous publication we hypothesized that Alzheimer's disease (AD ) can be induced by the age-related increase in expression of beta-amy loid precursor protein (beta APP) in the medial temporal lobe. Head in jury has also been identified as a risk factor for AD and as such, sim ilarities should exist between the pathology found after head injury a nd the earliest stages of pathology in AD. In this study, we have quan tified the number of beta APP-immunoreactive neurones in the medial te mporal cortex (pre-alpha cells, layer II) of 13 head injured and 17 co ntrol patients. Significantly more beta APP immunoreactive neurones we re observed in head injury cases (mean 18.4 per cluster) compared with controls (mean 13.4 per cluster, p < 0.05). These data provide a mech anism to explain how an environmental event such as head injury can ge nerate the same molecular pathology (increased neuronal beta APP) as i s found in the earliest stages of AD.