Age-associated neurodegenerative diseases
Dementia with Lewy bodies (DLB): It is characterized anatomically by the presence of Lewy bodies, clumps of alpha-synuclein and
  ubiquitin protein in neurons, detectable in post-mortem brain
  histology.[1] Lewy Body dementia affects 1.3 million individuals in
  the United States alone.


http://en.wikipedia.org/wiki/Dementia_with_Lewy_bodies


  Binswanger disease is a form of small vessel vascular dementia caused by damage to the white brain matter.[1] White matter atrophy
  can be caused by many circumstances including chronic hypertension as
  well as old age.[2] This disease is characterized by loss of memory
  and intellectual function and by changes in mood. These changes
  encompass what are known as executive functions of the brain.[3] It
  usually presents between 54 and 66 years of age, and the first
  symptoms are usually mental deterioration or stroke.[4]


http://en.wikipedia.org/wiki/Binswanger%27s_disease

To name the two with the highest prevalence after Alzheimer's and Parkinson's.