This question has been asked over and over, whether consuming such substances are proven to be perfectly healthy, without having effect of your physical/mental health, or that they should be forbidden in the face of society for its hidden properties that slowly ruin our physical perception without having the consciousness to know so. With different beliefs coming from different opinions, there has been research; science has finally provided an answer for society to realise the reality how soft drinks really affect our brain cognition. The research suggests that excess sugar (especially the fructose in sugary drinks) might damage your brain. Researchers ( that have utilised data from the Framingham Heart Study) found that people who drank soft drinks consistently are more likely to have poorer memory, a smaller overall brain volume, and a significantly smaller hippocampus (an area of the brain important for learning and memory).
Researchers examined the data, including MRI scans and cognitive testing results, from about 4,000 people enrolled in the FHS. The researchers looked at people who consumed more than two sugary drinks a day of any type: any type of soft drink, fruit juices, and other carbonated beverages, or more than three per week of soda alone. Among the individuals in the ‘high intake’ group, they found multiple indications of accelerated brain aging, including smaller overall brain volume, poorer episodic memory (the memory of autobiographical events; times, places, and associated emotions), and a shrunken hippocampus, all risk factors for early-stage Alzheimer's disease. Researchers also found that higher intake of diet soda, at least one per day, was associated with smaller brain volume.
The researchers took age, smoking, diet quality, and other factors into consideration, however they could not completely control for pre-existing conditions like diabetes, which may have developed over the course of the study and is a known risk factor for dementia. Diabetics generally drink more diet soda on average, as a way to limit their sugar consumption, and some of the correlation between diet soda intake and dementia may be due to diabetes as well as other cardiovascular risk factors. However, these pre-existing conditions cannot wholly explain the new findings.