For brain screening, check my eyes.

Alzheimer; News from the web:

Diseases of the central nervous system (CNS) may manifest as pathological changes in the retina of the eye. Research from the University of Eastern Finland (UEF) shows that retinal changes may be detected earlier than brain changes. Findings from mouse models suggest that eye examination could be used as a noninvasive screening tool for human brain diseases.

Read all about it HERE