Effects of Intermittent Fasting on Cognitive Performance and Metabolic Profile in Elderly Thėravada Buddhist Monks and Laypersons
ABSTRACT
The aging population is on the rise worldwide, and the problems associated with aging including cognitive impairment raises concern that needs urgent attention and action. Many studies have been conducted to find out how to prevent and delay age-related cognitive impairment and one of the popular regimes was caloric restriction and intermittent fasting.
The aim of the present study was to investigate the effects of short term and long term intermittent fasting on cognitive performance and metabolic profile of elderly Theravada Buddhist monks and laypersons.
The cognitive function of Theravada Buddhist monks and laypersons, aged between 20 to 79 years were assessed and compared age-wise; Group I was age between 20 and 39 years, Group II between 40 and 59 years and Group III between 60 and 79 years. A significant negative correlation between age and cognitive function was observed in both monks and laypersons (r=-0.492 and –0.344, respectively) and also in all subjects combined (r2=0.16) (p˂0.001).
In addition to cognitive functions, metabolic profiles such as blood glucose level (both fasting and postprandial), and serum lipid profiles (fasting total cholesterol, triacylglycerol, high density- and low density- lipoprotein cholesterol), and anthropometric parameters were also assessed in elderly monks (n=44) and in elderly laypersons (n=43). The body adiposity indexes (such as body weight, body mass index and waist circumference) were significantly lower in the monks than in their age-matched laypersons. Although fasting glucose (p˂0.001), postprandial glucose (p˂0.03), high density lipoprotein cholesterol (p˂0.01) and low density lipoprotein (p˂0.05) were significantly different between the monks and the laypersons, their cognitive scores were not. It was observed that the combined cognitive score of elderly Buddhist monks was positively correlated with BMI, and fasting blood glucose level in both elderly monks and laypersons indicate that memory was more dependent on the blood glucose level than other cognitive domains such as praxis, judgment, motor speed etc were. A significant positive correlation between combined cognitive score and LDL-C and LDL/TC ratio was observed in elderly participants (n=87).
The effect of short-term intermittent fasting on body adiposity, metabolic profile parameter and cognitive performance was investigated on laypersons (n=8) who observed 8 precepts (including fasting) for 10 days. The anthropometric parameters, blood glucose level, lipid profiles, and cognitive performance were determined before and after the short-term intermittent fasting. At the end of fasting period, memory score was significantly increased. Although body weight and body mass index did not significantly change, waist circumference significantly reduced indicating that the abdominal adiposity was significantly affected by short term intermittent fasting. Mean fasting blood glucose level was significantly decreased while mean 2-hour postprandial glucose level, total cholesterol and high density lipoprotein cholesterol were significantly increased after short term fasting.
On investigating the effect of feeding on blood glucose level and concurrent change in cognition in elderly monks and laypersons, it was found that both delayed memory recall and cognitive motor speed were significantly increased after breakfast in both groups but more so in the elderly monks than in the laypersons. The fasting blood glucose level was consistently lower and 2HPPG higher in the monks than in the laypersons. The increase in cognitive score was found to be correlated with increase in blood glucose level in the monks.
The long-term and short-term intermittent fasting has effects on cognitive function and metabolic profile in the elderly monks and laypersons. Increased cognitive performance after intermittent fasting seems to be partly due to change in metabolic parameters such as blood glucose and lipid levels and to cortical sensitivity to such change, In addition, years of religious practice and meditation might also contribute to increased cognitive performance in elderly monks.
Editor’s comment
Whilst it is well-established that cognitive function is closely associated with blood glucose level, the effect of intermittent fasting as in keeping the eight precepts, is unsettled. This paper sheds some light on other parameters like body adiposity indices.
Aye Aye Thein
MBBS, MMedSc, PhD
Associate Professor, Physiology Department, University of Medicine, Mandalay
Myat Thandar
MBBS, PhD
Head, Physiology Department, University of Medicine (1), Yangon
