A great deal of work was needed between 1985 and 1991 to firmly establish that tau is the main component of the aberrant filamentous tangles of AD (Brion et al., 1985; Delacourte et al., 1986; Goedert et al., 1988; Grundke-Iqbal, Iqbal, Quinlan, et al., 1986; Grundke-Iqbal, Iqbal, Tung, et al., 1986; Kondo et al., 1988; Kosik et al., 1986, 1988; Lee et al., 1991; Nukina & Ihara, 1986; Wischik, Novak, Edwards, et al., 1988; Wischik, Novak, Thøgersen, et al., 1988; Wood et al., 1986). This evidence concerns the gene MAPT and Alzheimer disease.