Question: is this a 2) strong advice, 1) weak advice 0) no advice?

Because there is no biomarker that can be used to confirm the clinical diagnosis and there is often a mixture of vascular and AD pathology found on autopsy [Fernando et al  2004; Lopez et al  2003b; Schneider et al  2007], genetic studies of AD based on case status may be complicated by substantial phenotypic heterogeneity. 
user
This is no advice
assistant