Neurology: Higher brain BDNF gene expression is associated with slower cognitive decline in older adult
Researchers in the US have found an association between the BDNF gene and a slower rate of cognitive decline in people with dementia. The research was published in the journal Neurology on 27 January 2016.
The researchers followed 535 volunteers with an average age of 81 and tracked their memory and thinking skills until death (an average of six years). After death, a clinician reviewed these tests to make a diagnosis of dementia or mild cognitive impairment, where appropriate. Mild cognitive impairment or MCI is a term used to describe mild memory and thinking difficulties not severe enough to be diagnosed as dementia. At the end of the study 138 people (26%) were assessed as having mild cognitive impairment, and 227 (42%) as having dementia. The research team went on to study generously donated brain tissue from the volunteers, focusing on the activity of a gene called BDNF. The protein produced by the BDNF gene plays an important role in keeping nerve cells healthy and encouraging new nerve cell growth.
The team found that there was an association between higher BDNF gene activity in the brain and a slower decline in memory and thinking skills in the years leading up to death. This association was strongest in people who had dementia compared to people who had MCI. The researchers also studied the volunteers with the most hallmark features of Alzheimer’s in their brains and found that those who also had higher levels of BDNF gene activity tended to decline more slowly than those with low levels of BDNF activity. The researchers suggest that BDNF may protect people with dementia from some of the underlying damage happening in the brain.There was no association between BDNF gene activity and memory and thinking skills in people who didn’t have MCI or dementia.
The researchers were also interested in DNA changes that may alter BDNF gene activity in the brain. They studied a particular change in the BDNF gene, which other researchers suggested could influence memory and thinking skills in later life. However, in this study, that change in the BDNF gene was not associated with altered levels of BDNF gene activity or rate of cognitive decline.
Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said:
“We know that dementia symptoms differ from person to person and researchers have long been exploring why memory and thinking skills decline faster in some people with the condition compared to others. This new research suggests that higher activity of a gene called BDNF is associated with a slightly slower rate of cognitive decline in people with early memory problems and dementia, but it’s unclear whether BDNF has a significant role in protecting memory and thinking skills or if there are other factors at play. It will be important to explore this link further in larger and longer studies, to further understand whether targeting BDNF levels could have any impact on dementia symptoms.”