This 2015 UCLA human study used the epigenetic clock methodology to find:

“All brain regions have similar DNAm ages in subjects younger than 80, but brain region becomes an increasingly significant determinant of age acceleration in older subjects. The cerebellum has a lower epigenetic age than other brain regions in older subjects.

To study age acceleration effects in non-brain tissues as well, we profiled a total of 30 tissues of a 112 year old woman. The cerebellum exhibited the lowest (negative) age acceleration effect compared to the remaining 29 other regions. In contrast, bone, bone marrow, and blood exhibit relatively older DNAm ages.”

Limitations included:

• “While the epigenetic age of blood has been shown to relate to biological age, the same cannot yet be said about brain tissue.
• Cellular heterogeneity may confound these results since the cerebellum involves distinct cell types.
• This cross-sectional analysis does not lend itself for dissecting cause and effect relationships.”

The study didn’t determine why the cerebellum was relatively younger. Some hypotheses were:

• “Our findings suggest that cerebellar DNA is epigenetically more stable and requires less ‘maintenance work.’
• The cerebellum has a lower metabolic rate than cortex.
• It has far fewer mitochondrial DNA (mtDNA) deletions than cortex especially in older subjects, and it accumulates less oxidative damage to both mtDNA and nuclear DNA than does cortex.”

http://impactaging.com/papers/v7/n5/full/100742.html “The cerebellum ages slowly according to the epigenetic clock”