People with Alzheimer's disease tend to have lower levels of BDNF in brain areas important for memory, and the lower the BDNF levels, the worse their memory problems tend to be.
Scientific Claim
BDNF levels are reduced in Alzheimer's disease patients, particularly in the hippocampus, parietal, entorhinal and frontal cortex, and these reductions correlate with disease severity and episodic memory performance.
Source Excerpt
“Reduced levels of BDNF have been reported not only under normal aging conditions but also in pathological conditions including Huntington (HT), Alzheimer’s disease (AD), and Parkinson’s disease. BDNF protein and mRNA levels as well as proBDNF are reduced in the post-mortem brain of AD patients compared with age-matched controls, with no changes in TrkB levels. This reduction was also reported in Mild Cognitive Impairment (MCI), a potentially prodromal stage of AD. Furthermore, reduced circulating levels of BDNF were also found in MCI. BDNF levels are correlated to the severity of the disease and with episodic memory performance in patients, suggesting that these decreases could be related to the pathogenesis of the disease. In conclusion, downregulation of BDNF and proBDNF are thought to be an underlying mechanism related to early AD.”
Evidence from Studies
Supporting Studies
Brain-Derived Neurotrophic Factor: A Key Molecule for Memory in the Healthy and the Pathological Brain
The study describes multiple studies showing reduced BDNF levels in AD patients and correlations with disease severity and memory performance. The language used is appropriately correlational, noting 'correlated to' and 'suggesting that these decreases could be related to'.