The design and sampling frame are grounded in the establishment of a comprehensive database employing a sequential research design.
Participants undergo annual history and physicals.
Comprehensive examinations including psychological, support and functional profiles are conducted at five-year intervals. Nearly all people reported gradual changes. The average duration from onset to time of change is 15.8 years. There does not appear to be a relationship between current age and reports of change nor between duration and change. However, there may be a correlation between age at onset and the number of years before change occurs.