High intensity interval training and its impact on brain-derived neurotrophic factor: a potential mechanism to reduce early onset dementia

• Dementia results in memory loss and cognitive decline and is a leading cause of death globally. • Brain derived neurotrophic factor (BDNF) stimulates neurogenesis in the hippocampus to improve memory and cognition. • Blood Lactate is a potent stimulant of BDNF expression. • High intensity interval training (HIIT) elevates blood lactate. • HIIT may slow the progression of early onset dementia as it profoundly elevates blood lactate and BDNF. Dementia is an age-related disease affecting the brain that results in memory loss and cognitive decline. It is the seventh most common cause of death globally. Early (younger) onset dementia is any form of dementia that occurs in people between the ages of 14 to 65 years. Lifestyle interventions such as exercise and physical activity can be effective in preventing and attenuating early onset of dementia progression. Exercise stimulates neurogenesis in the hippocampus and can increase hippocampus volume. This leads to improved memory retention and cognitive capability. Brain derived neurotrophic factor (BDNF) is a key protein that promotes the growth and survival of hippocampus neurons. Exercise elevates BDNF in the hippocampus, however, current evidence suggests the exercise intensity should be strenuous to maximise its stimulatory effect as it profoundly elevates the muscle metabolite lactate. Lactate is consequently transported into the blood and crosses the blood–brain barrier to move into the hippocampus to stimulate BDNF expression. Therefore, conservative low intensity constant rate exercise prescription may be insufficient to impact BDNF concentration as it is characterized by stable blood lactate concentration. An alternate and safe exercise method that stimulates lactate is high intensity interval training (HIIT). Subsequently we hypothesize long term HIIT will prevent and slow the progression of early onset dementia more so than constant rate, moderate intensity exercise as it more profoundly elevates blood lactate and BDNF.