Quantifying hippocampal neurogenesis in the living human brain and its relevance for long-term memory

Human aging is characterized by neurodegeneration and decline in long-term memory, creating major individual and societal costs.

Neurogenesis describes the brain’s ability to produce new neurons into very old age, as shown in animal and human autopsy data. Adult neurogenesis occurs in the hippocampus and is necessary for successful long-term memory. Based on animal data, it is well-established that neurogenesis is crucial for memory formation and consolidation.

Further, depression is associated with decreased hippocampal neurogenesis.So far, however, the importance of neurogenesis for human long-term memory and mental health has been elusive due to difficulties of quantifying biomarkers of neurogenesis in the living human brain using non-invasive measures.

With new groundbreaking developments, it is now feasible to detect human neurogenic signals in vivo.

Therefore, we hypothesize that the higher hippocampal neurogenic signal is related to better neurocognitive mechanisms underlying memory and lower expression of depression symptoms in middle-aged and older adults.

Informed by well-established evidence from animal data, we further probe whether a 6-month intervention with Metformin, a drug used to treat type 2 diabetes, increases neurogenic signals, consequently resulting in better memory and mental health.

Overall, our findings will shed light on basic mechanisms underlying human memory, which may contribute to maintenance of cognition and mental health into old age.