We’ve all heard that breakfast is the most important meal of the day. But skipping breakfast is becoming more common than ever due to busy lifestyles and the popularity of fasting diets.

This article will break down a recent study by Ishizuka et al. (2022) that looked at whether breakfast skipping is linked with cognitive scores in a group of Japanese older adults (1).

What was the study investigating?

This study was designed to investigate the long-term effect of skipping breakfast once or more per week on cognitive function in older adults (60 years and above).

Cognitive function means brain-based abilities like thinking, learning, memory, attention, reasoning, making decisions, and problem-solving (2).

Study methods

This study followed 712 Japanese men and women over 31 months. The participants were 60 and above (with an average age of around 71) and they were living in the community rather than in care homes.

The researchers compared average declines in cognitive scores between breakfast-skippers and breakfast eaters. Breakfast skippers were defined as those who reported skipping breakfast once or more per week.

Cognitive score was assessed by trained psychologists using the Mini-Mental State Examination (MMSE) at baseline and follow-up.

The Mini-Mental State Examination (MMSE) is a tool that uses 11 questions to test cognitive function in terms of: orientation, registration, attention and calculation, recall, and language. The highest possible score on the MMSE is 30 and scoring 23 or lower can indicate cognitive impairment like dementia (3).

The researchers used a decrease in MMSE score of 2 or more to indicate a reduction in cognition.

Dietary intake was assessed using a food frequency questionnaire which was compared to a 7-day weighed food diary to check for accuracy.

The researchers also measured the participants:

• Weight and height - to calculate BMI

• Smoking status

• Alcohol intake

• Physical activity level

• Average sleep duration

• Medication

• Socioeconomic status - including household income and education

• Symptoms of depression

• Medical history in relation to high blood pressure and diabetes

What did they find?

After adjusting for baseline MMSE scores, the average decline in cognitive score was significantly higher in breakfast skippers than breakfast eaters (by 1 MMSE point). This association remained significant when factors like age and gender were taken into account.

A stronger association was seen between breakfast skipping and cognitive decline when the cut-off value used for the cognitive score was increased from a decline of 2 to 3 MMSE points. Reducing the MMSE score cut off to 1 point also found a significant association, including when those with cognitive impairment or those who lived alone were excluded.

Those who missed breakfast at least once per week were also found to have more symptoms of depression and a higher BMI.

In terms of dietary intake, breakfast skippers were found to:

• Consumed significantly less fruit, vegetables and fish

• Have a lower intake of nutrients, including protein, fibre, potassium, thiamine, and vitamin A,D, E, and K

What does this mean?

This study suggests that skipping breakfast once per week or more is linked with a reduction in cognitive function in adults aged 60 or older.

Not eating breakfast every day was also associated with a lower intake of fruit, vegetables, and fish which led to a lower intake of protein, fibre, potassium, and a number of vitamins and antioxidants.

This difference in nutritional intake could have impacted the reduction in cognition; as diets high in fruit, vegetables, fish, and antioxidants like the Mediterranean or traditional Japanese/Okinawan diet are known to benefit brain health (4, 5).

The findings of this study are in line with previous studies that have found that skipping breakfast impairs cognition in children, teens and adults (6, 7). However, less is known about the long-term cognitive impact of skipping breakfast for older adults.

Eating breakfast provides nutrition and energy to fuel brain health and function. Interestingly, a small study from 2019 found that eating in the earlier part of the day was linked with an increase in a chemical the brain releases called brain-derived neurotropic factor (BNDF) which is involved in brain repair and developing new neural connections (8).

Skipping breakfast has also been linked with (9, 10, 11):  

• Weight gain

• Worsened heart health

• Higher risk of type 2 diabetes and stroke 

• Increased mortality for heart disease and all causes

As with all research, it’s important to acknowledge the limitations of this study:

• The participants in this study were older adults from Japan so this may not be applicable to other groups of people. Especially as breakfast in Japan tends to be very different and often more nutritious to those in the West — including vegetables, fish, seaweed, fermented soya beans and rice (etc.). 

• Participants also weren’t selected at random and there were only 29 ‘breakfast skippers’ - both of these can impact the strength of the results. 

• ‘Breakfast skipping’ was defined as missing breakfast once per week or more, but many people who wouldn’t consider themselves to be breakfast skipper might end up accidentally missing breakfast once per week. Therefore, this doesn’t tell us whether there was much difference between skipping breakfast once per week versus everyday.

• The dietary information was collected via a food frequency questionnaire which is known for issues with accuracy of reported intake. 

• MMSE score alone, rather than including dementia diagnoses, was used to determine reduced cognition. 

Future research that addresses these limitations is needed in order to build a stronger evidence base in this area.

Summary

This study of older Japanese adults found that missing breakfast once or more per week is associated with reduced cognitive function as measured by a significant reduction in MMSE (Mini-Mental State Examination) score.

Skipping breakfast was also linked with consuming less fruit, vegetables and fish which had a knock-on impact on nutritional intake, including those known to impact brain health such as antioxidants.

This suggests that skipping breakfast or fasting in the morning might not be good for older adults when it comes to brain functions like thinking, learning, memory, and decision making.

These findings are interesting and in line with other similar research. But future large studies are needed in different population groups, and it would be helpful if frequency of breakfast skipping was examined more closely, along with using the most accurate methods for measuring dietary intake and cognition as possible.