Constantinidis and De Ajuriaguerra (1965) studied the brain from 64 elderly persons, from 30 families, with various psychiatric diagnoses, for the presence of senile plaques independent of associated cerebral lesions. Of 29 pairs of sibs, 22 pairs had senile plaques, 4 pairs were unaffected, and 3 pairs had 1 affected. Although the authors postulated recessive inheritance, it should be noted that of 10 two-generation observations, parent and child were affected in 3, and 1 generation only in 7.
Constantinidis, J., De Ajuriaguerra, J. L'incidence familiale des plaques seniles. Confin. Psychiat. 8: 130-137, 1965. [PubMed: 5886992]