A six-minute HIIT workout may help delay Alzheimer's and Parkinson's disease

Researchers have shown that intermittent fasting and a physically active lifestyle may slow age-related cognitive decline.

Recent research has found that exercise, in particular short bursts of high-intensity exercise, can increase brain-derived neurotrophic factor (BDNF) levels in the body. The study found that high-intensity activity is more efficient in increasing the level of DBNF than fasting alone.

Cognitive performance declines with age. According to research, cognitive ability peaks around 30 years old [1].

Symptoms of cognitive decline associated with aging include [2]:

There is a slowdown in reasoning abilities and problem-solving abilities
Reduced verbal and numerical abilities
Having trouble remembering things

Despite the fact that some cognitive decline is inevitable, research suggests sufficient nutrition and exercise can help keep the body and the mind healthy [3, 4]. There is a notable amount of evidence indicating that exercise has a significant ability to lower the risk of cognitive decline.

“Preventative lifestyle medicine” is more about percentage risk reduction, which is possibly greater along with more than one lifestyle change, said Ryan Glatt, senior brain health coach and director of Pacific Neuroscience Institute in Santa Monica. [5].

Addressing the decline

A combination of intermittent fasting (IF) and exercise has been shown to slow down age-related cognitive decline. Nevertheless, both processes cause a “cerebral substrate switch,” rerouting the brain’s primary fuel source from glucose to fat [6].

Research shows that IF reduces glucose levels and increases circulating ketones, which become the brain’s primary fuel source [7]. The brain is also fuelled by lactate, which is produced by muscles during exercise [8].

HIIT and the brain

A switch in fuel is associated with an increase in neuroprotective protein, BDNF, which is associated with brain health [9, 10]. The function of learning and memory is impacted by BDNF, as it plays an important role in cell survival and growth.

Neurodegenerative diseases like Alzheimer’s and Parkinson’s have been linked to low levels of BDNF. The University of Otago’s Dr Kate N Thomas led a research that found even short bursts of high-intensity exercise can increase BDNF levels. This was published in The Journal of Physiology [11].

Comparing high and low-intensity workouts

In a cross-over trial, the researchers studied 12 healthy individuals ages 18 to 56 [12]. The majority of participants were female, had a BMI below 25, and exercised regularly. Trial participants with chronic diseases and on daily medications were excluded.

Four different study regimes were applied to the participants:

Fasting for 20 hours
90-minute low-intensity cycling calculated at 25 percent of the participant’s peak oxygen consumption
Cycling at 100 percent of the participant’s peak oxygen consumption for six minutes
Combining exercise and fasting

A series of blood samples were collected throughout the trial to measure BDNF, glucose, insulin and ketone bodies beta-hydroxybutyrate alongside platelet counts [13].

HIIT vs fasting

There was a 9-fold increase in ketone body availability after the 20-hour fast, but no noticeable difference in BDNF levels. Compared to fasting, light cycling raised serum BDNF by up to 14 percent after 90 minutes. It was associated with an increase of 13 percent in blood platelets, the researchers discovered.

Six minutes of high-intensity cycling increased circulating BDNF levels five times more than longer sessions of low-intensity cycling. Regardless of whether participants fasted or not, the increase was linked to a 6-fold increase in lactate levels. An increase in lactate level was not evident during low-intensity exercise.

The research team also found that exercise increased the number of circulating platelets by 20 percent, to which they concluded exercise has a more significant impact on platelet count than fasting.

Is all exercise equal?

According to the study’s first author Travis Gibbons, about the importance of the type of exercise in this study.

He explained that any exercise is perfectly okay, as long as the intensity can be high enough to produce some lactate. The intensity required to do that is relative to each individual.

He added that the participants in the study worked hard but not at their peak work rate. His most straightforward suggestion to anyone looking to achieve similar results was to “go all-out for 20-40 [seconds]”. People have a pretty good sense of pacing and will “pick an intensity they feel can be sustained for at least that period,” he noted.

What makes the study stand out

This data encourages people to live active outdoors, which is the answer to many modern-day (Westernised) health problems just beyond our doorstep. Getting outside and moving throughout aging is a much simpler, effective and equitable method of preserving health than seeking cures,” according to Gibbons. Glatt agrees.

Research limitations

Since this study has a low statistical power and a multimodal design, it raises more questions than it answers. According to the authors, however, exercise is a “accessible, affordable, efficient and equitable intervention” that can be easily incorporated into daily life.

As cognition or other aspects of brain function were not measured in this study, Glatt added that it may be unclear what significance BDNF expression has in this context. He emphasised that future research would need to focus on “how significant those benefits are, what sorts of benefits exist (cognitive, brain function or structure or mood), and how long those benefits may last.

Can exercise and fasting protect the brain?

The next step for this work is to understand if combining exercise and fasting alters the neuroprotective effects. This will inform methods more about the ideal ‘timing’ of exercise to achieve the best stimulus for brain-specific adaptations,” noted Gibbons.

The team is also interested in understanding how exercise affects the blood in the brain and is working on research that will allow them to sample blood from the brain during exercise. We know that the blood in our brain is very different from that in the rest of our body.