It is my theory, based on prevailing evidence, that neurodegeneration is initiated by vascular inflammatory free radical interstitial space impingement and a subsequent blockage of the endothelial and capillary cell dance. It is associated with:  Vascular inflammatory free radical stealth migration through capillary cell membranes, attachment to capillary cell basement membranes and pluming an immune arsenal response towards their attachment. If not completely removed, chronic inflammation establishes a foothold.  Perpetuated endothelial and capillary cell outer membrane increases in permeability fixates their mitochondria into energy combustion to support outer membrane active transport processes. This blocks the back and forth rhythm in outer membrane permeability and mitochondrial combustion from energy to nitric oxide.  The blocked capillary cell pivot and swing dance limits mitochondrial nitric oxide production while energy combustion goes on overdrive. With less nitric oxide combustion, superoxide free radicals increase and nitric oxide induced rejuvenation of capillary infrastructure decreases.  As nuclear DNA coding is silenced from increasing superoxide free radical damage, effective protein synthesis diminishes and capillary cells of the blood brain barrier cannot regenerate mitochondria, outer membrane receptors or infrastructure. Mitochondrial volumes and outer membrane receptors decrease (pseudocapillarization).  Pseudocapillarization coupled with ineffective mitochondrial energy support renders capillary cells dysfunctional. They lose control of feedback loop signaling to adjoining astrocytes, pericytes and brain cells while enabling a wayward array of different white blood cells and cytokines access into the brain's interstitial spaces-cerebrospinal fluid.  These wayward cells accumulate and rather than working for sanitation of the interstitial space they work against it. They do this by establishing a counter feedback loop signaling control of the brains interstitial space, utilizing cytokine signals that run counter to sanitation and in deference to the feedback loops of the fading capillary cell.