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Title: The Effects of Sugar Consumption on Brain Function
Name: Ashfarin Nasiha
Course: ENGL 210
Instructor: Brandon Borcoman
Date: 06/30/26

Introduction

Glucose, a form of sugar, is essential for proper brain function and provides a primary energy source for cognition but excessive sugar intake may negatively affect brain health. Past research such as The impact of sugar consumption on stress driven, emotional and addictive behaviors by Jacques et al. (2019) and  Effects of sucrose consumption on memory and the gut microbiome by Hsu et al. (2021) shows that sugar influences brain systems such as reward processing, memories and emotional regulation. Furthermore, according to Raza et al. (2024), excess sugar consumption triggers reward processing in the brain, making one crave sugar.

However, there is still a need to combine findings across human and animal studies to get a better understanding of how sugar affects both behavior and underlying brain mechanisms, including memory decline and emotional instability.

This study asks, “ How does excessive sugar consumption affect brain function, memory, emotional behavior and responses similar to addiction?” This question is necessary because it helps determine how uncontrolled sugar consumption contributes to long term effects on cognitive and neurological effects.

To address this, a literature based peer reviewed human and rodent studies review was conducted. The findings were analyzed here to compare how sugar intake influences brain function, behavior and neurological changes across different experimental models.

Materials and Methods

This study was conducted as a literature based review using peer reviewed scientific articles obtained from online academic databases. The research process began by searching for the keyword “sugar consumption affecting the brain.” This search led to two primary sources: Jacques et al. (2019), The Impact of Sugar Consumption on Stress Driven, Emotional and Addictive Behaviors and Hsu et al. (2021), Effects of Sucrose Consumption on Memory and the Gut Microbiome. To further investigate the long term effects of sugar on the brain, an additional search was performed using the keyword “how sugar affects the brain in long term consumption.” Through this search, the study by Raza et al. (2024), Sugar Consumption and Its Effects on Reward Processing, Cravings and Addictive Behaviors was selected because it provided detailed evidence and statistical findings on reward processing and addictive behaviors associated with excessive sugar intake.

In the beginning of the investigation, each research paper was skimmed to understand its objectives, study subjects, methods and major findings.Then notes were taken on why each article is useful in answering the research question regarding the effects of sugar consumption on the brain. After confirming that the studies directly addressed brain function and long term sugar intake, the articles were viewed in detail and important information was rough drafted as the reading progressed. Next emphasis was given to experimental results involving both human participants and rodents because the sources provided evidence of how sugar alters brain function with details.

Later the drafted notes from each study were compared according to the main question of the investigation which is, how does excessive sugar consumption affect the brain and why is understanding these effects important? Only the most important findings, relevant data and observations were selected. These included statistics on psychiatric events, dementia risk, dopamine receptor changes, anxiety related behaviors, memory deficits and hippocampal degeneration.

Finally, the findings from the human and rodent studies were synthesized and placed into a table. It was organized in the table because the evidence in table form made the relationships between sugar exposure, brain changes, observed consequences and affected brain functions clear and easier for readers to understand how excessive sugar consumption can contribute to addiction, impaired memory, mood swings and neurodegenerative conditions.

Results

Evidence from both human and rodent studies illustrated that high sugar intake produces neurological and behavioral changes that resemble addiction and may contribute to long term cognitive decline. Here, the data and factual observations gathered from the three primary sources reveal distinct neurological, behavioral and physiological outcomes associated with sugar consumption.

Table1:Evidence Linking Sugar Consumption to Brain Dysfunction

Study Subjects and Sugar Exposure	Observed Effects	Changes in the Brain	Brain Function Affected
human adults followed for 5 years with varying levels of sugar intake (4,392 psychiatric events recorded)	adult men with high sugar intake had a 23% greater risk of developing common mental disorders	reduced brain derived neurotrophic factor and neurons loss in the prefrontal cortex	mood and executive control
older adults monitored over a long term period (118 dementia cases)	high sugar intake doubled dementia risk , while high fructose intake nearly tripled dementia risk	brain changes caused with degeneration of the hippocampus	dementia and neurodegeneration
adolescent rats given continuous access to an 11% sucrose solution	poorer memory and spatial learning tests. memory deficits were also transferred to healthy rats through fecal transplantation	changes in the gut bacteria and changes in the hippocampal gene expression	memory and learning
rodents given a 10% sucrose solution with intermittent access (12 hours on, 12 hours off)	withdrawal symptoms, increased anxiety and higher requirement of sugar to achieve the same reward effect	overflow of dopamine in the nucleus accumbens and reduced d₂ receptors for dopamine	addiction and  reward system

Table 2: Brain Functions Affected by Excessive Sugar Consumption

Brain Function	Brain Region Involved	Observed Effect
reward processing	mesolimbic dopamine pathway and nucleus accumbens	more sensitivity to increased dopamine, stronger cravings and reward seeking behavior
emotional regulation	prefrontal cortex	increased stress sensitivity, anxiety like behaviors and emotional instability
memory and learning	hippocampus	difficulty in memory formation and poor spatial learning capabilities
long term cognitive health	hippocampus and cortical neurons	more risk of cognitive impairment and dementia

The studies have also found that repeated intake of sugar leads to alteration in the mechanism of dopamine, impairment of gut-brain connection and structural changes in the brain such as those of the hippocampus, prefrontal cortex and mesolimbic reward pathway. This led to craving behavior, anxiety, poor memory function and development of psychological illnesses and dementia.

Rodents that were provided access to a 10% sucrose solution on an alternating 12 hour basis had enhanced dopamine production in the nucleus accumbens with lower levels of dopamine D₂ receptors. These alterations led to withdrawal behavior, increased anxiety and requirement of higher sugar quantities for the rewarding effects.

In a 5 year study of adults with different sugar intake levels the researchers recorded 4,392 psychiatric events. People with high sugar intake showed reduced brain derived neurotrophic factor (BDNF) and neuronal loss in the prefrontal cortex. While adult men with high sugar intake had a 23% greater risk of developing common mental disorders (OR = 1.23; 95% CI: 1.02-1.48).

Similarly adolescent rats continuously exposed to an 11% sucrose solution developed altered gut bacteria and changes in hippocampal gene expression. These rats also performed badly on memory and spatial learning tests and the memory deficits were also transferred to healthy rats through fecal transplantation, suggesting a strong gut brain connection.

In older adults over a long term period monitoring found 118 dementia cases. As such high sugar intake was associated with hippocampal degeneration and doubled the risk of dementia (HR = 2.10; 95% CI: 1.05-4.19) and high fructose intake was linked to an even greater tripling rate of dementia risk (HR = 2.80; 95% CI: 1.38-5.67).

So, the findings show that excessive sugar consumption disrupts the brain’s reward pathways, impairs memory and learning, negatively affects emotional regulation and increases the risk of long term neurodegenerative diseases.

Discussion

The results of this study clearly indicate the possible negative impact of high sugar intake on brain health. Sugar consumption was found to disrupt brain functions responsible for reward, memory and emotions.

The evidence indicates that sugar can alter the brain’s reward system in ways similar to addictive substances.  The rats drinking 10% sucrose solution exhibited higher levels of dopamine release, had withdrawal symptoms, were more anxious, and required bigger sugar quantities to feel its rewarding properties. These findings suggest that repeated sugar consumption can encourage cravings and eating behaviors typical for addictions.

Also high sugar intake was linked to poorer mental and cognitive health. In a 5 year study with 4,392 psychiatric events, high sugar consumption increased the risk of common mental disorders by 23% (OR = 1.23). Adolescent rats on an 11% sucrose diet also showed impaired memory and learning due to changes in gut bacteria and hippocampal function. More importantly, long term data proves serious brain risks. High sugar intake doubled dementia risk (HR = 2.10), while high fructose intake nearly tripled it (HR = 2.80), showing strong evidence that excessive sugar contributes to long term brain decline.

Limitation
The present study is based on literature review and suffers from firstly; the results obtained in this study were based solely on information from previously conducted research works and not on experiments specifically designed for the current study. The use of different methodologies in those primary studies, their differences in terms of sample size, as well as the exactness of the studies may have impacted the results achieved. Next the samples of animals and humans that were used in these studies varied and were dissimilar; some experiments were conducted on animals while others were done on healthy people with different timeline altho the reason for doing so was the lack of information needed but at the same time it achieved the combined proof from evidence that excessive sugar intake is responsible for declined brain functions. 

Abstract

The purpose of this study is to investigate how high sugar consumption influences memory, reward processing, behavior and addictive tendencies. As a result literature review was conducted using peer reviewed scientific articles.

In this lab report, we examined how sugar consumption affects brain function by analyzing findings from published scientific studies involving both human participants and rodents. The studies observed different groups of people over specific periods of time and recorded their levels of sugar intake, their behavioral and neurological responses and the consequences associated with excessive consumption. The findings showed that individuals with high sugar intake experienced increased risks of mental health disorders, memory decline and neurodegenerative conditions such as dementia.

To further understand in depth mechanisms behind these outcomes, results from rodent studies were also analyzed. Rodents were exposed to controlled amounts of sucrose solutions, allowing researchers to observe how the brain processes sugar and why excessive consumption can become difficult to control. The studies found that repeated sugar intake altered dopamine signaling in the brain’s reward system, produced withdrawal symptoms and anxiety that caused changes in brain regions responsible for memory and learning. These findings suggest that excessive sugar consumption can disrupt normal brain function and activate unbalanced reward pathways that encourage cravings for sugar potentially leading to long term cognitive and emotional consequences.

Conclusion

The scientific evidence here demonstrates that excessive sugar consumption negatively impacts brain health. The high sugar intake impairs memory, altering brain communication, overstimulating reward pathways and promoting addictive behaviors and emotional disturbances. Overall, the findings suggest that reducing added sugar intake may help preserve cognitive function and support healthier brain activity. Maintaining moderate sugar consumption is therefore important not only for physical health but also for protecting learning ability, emotional stability and long term neurological health. This lab report was made in the hopes of persuading individual readers to take less sugar knowing the long term effects on the brain. 

References

Jacques, A., Chaaya, N., Beecher, K., Ali, S. A., Belmer, A., & Bartlett, S. (2019). The impact of sugar consumption on stress driven, emotional and addictive behaviors. Neuroscience & Biobehavioral Reviews, 103, 178–199. https://pmc.ncbi.nlm.nih.gov/articles/PMC5532289/

Hsu, T. M., Konanur, V. R., Taing, L., Usui, R., Kayser, B. D., Goran, M. I., & Kanoski, S. E. (2021). Effects of sucrose consumption on memory and the gut microbiome. Molecular Psychiatry, 26(8), 4260–4273. https://doi.org/10.1038/s41398-021-01309-7 

Raza, M., Ahmed, A., Ahmed, M. U., Shah, S. A. A., Fatima, H., & Afzal, M. (2024). Sugar consumption and its effects on reward processing, cravings and addictive behaviors. Cureus, 16(2), e54682. https://pmc.ncbi.nlm.nih.gov/articles/PMC10921393/