The Association Between a High-Sugar, High-Fat Diet and Cognitive Decline

Understanding the potential dietary effects on cognition is imperative when constructing a patient’s care plan

The link between conditions such as diabetes and Alzheimer’s has been a key area of interest in recent years, encouraging key lifestyle changes.

Below is a summary of three recent studies, all which address dietary variables and, more specifically, blood sugar levels in relation to cognition. Understanding how diet impacts potential cognitive defects, will help you actively make proactive recommendations.

Study 1: HbA1c, Diabetes and Cognitive Decline: The English Longitudinal Study of Aging

As published in Diabetologia, researchers were interested in the association between diabetes status, HbA1c levels and cognitive decline. Studying 5,189 participants, this longitudinal study took place over a 10-year follow-up period.

  • The participants were 55.1 percent female, with an average age of 65.9. At baseline, HbA1c levels ranged between 15.9 and 126.3 mmol/mol.
  • It was found that an average increment of 1 mmol/mol was significantly associated with an increased rate of cognitive decline. Memory, orientation and executive function scores all showed an increased rate of decline in relation to diabetes.
  • It was concluded that there is a significant association between diabetes status, HbA1c levels and elevated rates of cognitive decline.
  • In the future, the researchers plan to study the effect of optimal glucose control on cognition among patients with diabetes.

Study 2: Sugar Highs and Lows: The Impact of Diet on Cognitive Function

In a separate review, published in The Journal of Physiology, the impact of a high-sugar, highly processed diet was analyzed, based on the standard Western diet. Researchers were concerned about three distinct diseases: diabetes, cardiovascular disease and cancer.

In more recent years, the effect of this diet in relation to cognition has been a key area of interest. For example, past evidence has shown that a greater intake of antioxidants, B-vitamins and polyunsaturated fatty acids during middle age may actually curb cognitive decline in later years.

Interested in the consequences of high sugar consumption and an omega-3 deficiency, Agrawal and Gomez-Pinilla found that this type of diet leads to lower cognitive scores and insulin resistance. They theorized that insulin resistance would directly impact memory and learning. Low cerebral blood flow was also an area of concern.

It was concluded that many important risk factors exist for cognitive decline, which are directly linked to the vascular system. These include diabetes, sleep apnea, hypertension, hyperlipidemia and physical inactivity. Although more research is required, these modified factors should be addressed in public health guidelines.

Study 3: Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms, and Nutritional Interventions

Focusing on the link between diet and cognitive impairment, this study was published in Nutrients. By observing the effect of a high-fat, high-sugar diet on cognition, the researchers were able to assess the role of high-energy diets in relation to cognitive deficits.

Diet-induced decline can be measured by assessing mechanisms, such as brain-derived neurotrophic factor and inflammation. It is believed that hippocampal-dependent memory is particularly vulnerable to the effects of a poor diet, largely based on the health consequences of obesity.

After reviewing the available research, it was concluded that a diet high in either fat or sugar can impair cognition. In fact, memory deficits can occur within just one week of high-energy diet exposure. This may be due to elevated inflammation in the central nervous system.

In contrast, the researchers discussed the positive effect of omega-3 and curcumin. They show promise in terms of prevention, with a positive impact on both neuroplasticity and inflammation. In turn, this may reduce the rate of decline as physicians aim to stop the current obesity trend.

As the available research continues to unfold, the public must change modifiable lifestyle variables in order to curb chronic disease and protect neurocognitive function.


  • Zheng, F., Yan, L., Yang, Z., Zhong, B., & Xie, W. (2017). HbA1c, diabetes and cognitive decline: the English longitudinal study of ageing. Diabetologia, 61(4), 839-848. Retrieved from
  • Barnes, J.N., & Joyner, M.J. (2012). Sugar highs and lows: the impact of diet on cognitive function. The Journal of Physiology, 590(Pt 12), 2831. doi: 10.1113/jphysiol.2012.234328.
  • Beilharz, J.E., Maniam, J., & Morris, M.J. (2015). Diet-induced cognitive deficits: the role of fat and sugar, potential mechanisms and nutritional interventions. Nutrients, 7(8), 6719-6738. doi: 10.3390/nu7085307.

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