Alzheimer’s disease is a disorder of unknown and likely multiple aetiologies. The authors of this paper investigated the hypothesis that Alzheimer’s disease may represent a brain-specific form of insulin-resistance. Insulin is known to be synthesized in the brain and is involved in memory formation. The authors quantified the numbers of cells expressing insulin receptor β-subunit (IRβ) and phosphorylated PPARγ (PPARγ(p)) in post-mortem hippocampus (dorsal/ventral) and frontal cortex of patients with Alzheimer’s Disease, Alzheimer’s Disease combined with type 2 diabetes mellitus, type 2 diabetes mellitus alone, and from aged-matched controls. They found significant reductions in IRβ positive cells in Alzheimer’s Disease cases compared to all other groups in all investigated brain regions. They also observed significantly more PPARγ(p) positive cells in each patient group compared to control. The study concluded that Alzheimer’s Disease and type 2 diabetes may not be directly linked, but may share common histological features including lower numbers of IRβ positive cells and higher numbers of PPARγ(p) positive cells in specific brain regions. Whether these results explain the increased frequency of Alzeimer’s Disease in elderly diabetic patients remains for future study.
Bartl J, Monoranu CM, Wagner AK, Kolter J, Riederer P, Grünblatt E: Alzheimer’s disease and type 2 diabetes: Two diseases, one common link? World Journal of Biological Psychiatry [Epub ahead of print, February 14, 2012; doi:10.3109/15622975.2011.650204]