βAP deposition and head trauma

Head trauma is considered to be a risk factor for Alzheimerʹs disease, because a high prevalence of βAP deposits has repeatedly been reported in patients who died within a few days following head injury. To evaluate this statement, we undertook two studies using immunohistochemistry for βAP and found a surprisingly low prevalence of βAP diffuse deposits. We first selected 23 patients aged 17–63 years, who died 0–76 days after head trauma. Using βAP antibody at the usual dilution (1:100), we did not find any deposits. With a high concentration of antibody (dilution 1:2) we found βAP diffuse deposits in one 46-year-old case. In a second study, 17 patients aged 60–79 years old, who died 1–35 days after head injury, were compared to a control group. We did not find any significant difference in the density of βAP diffuse deposits between cases and controls using usual dilutions of βAP antibody. The density of βAP diffuse deposits was linked only to aging and the presence of senile plaques.