Whether it's a morning espresso followed by an English breakfast of toast or a quick cup of instant drink between meetings, moderate caffeine intake during the day is associated with a reduced risk of worsening dementia.
A new study has now confirmed the link between caffeine intake and cerebrospinal fluid markers of Alzheimer's disease, Science alert reported.
Most previous research has focused on observational studies or meta-analyses of tea and coffee consumption, with relatively little information gathered on the biological changes that caffeine induces.
A team from France examined data from a prospective study that evaluated patients with mild cognitive impairment or Alzheimer's disease between 2010 and 2015.
Their analysis of 263 participants over the age of 70 included a baseline clinical assessment and a detailed study of their consumption of foods and beverages such as coffee, chocolate, tea and carbonated drinks to assess the amount of caffeine absorbed by their bodies each day. The volunteers also underwent MRI scans and had blood and cerebrospinal fluid (CSF) samples taken.
Individuals who consumed an average of just over 200 milligrams of caffeine per day were grouped into a "low caffeine" sample, and those who drank more were considered higher caffeine consumers.
The difference equated to one can of energy drink or one or two cups of coffee per day, compared to several cans or cups respectively - a difference that may influence the pathology responsible for dementia.
The team found that lower caffeine consumption correlated with a higher risk of mild cognitive decline with impaired memory, compared with higher caffeine consumption. In fact, individuals in the low caffeine consumption group were nearly 2.5 times more likely to be diagnosed with mild cognitive impairment with memory impairment or Alzheimer's disease.
Closer examination of the proteins in the participants' GMT also revealed significant differences in the ratios and concentrations of specific forms of beta-amyloid proteins. Those who drank less caffeine tended to have lower concentrations of a soluble form called Aβ42, with reduced ratios of Aβ42 to another form called Aβ40.
They also had reduced ratios between Aβ42 and a form of tau protein called ptau-181, compared with those who drank larger amounts of caffeine.
Taken together, these specific protein levels in the GMT in those who consumed less caffeine signify an increased accumulation of beta-amyloid proteins in the brain, which is a biological feature of the neurodegeneration responsible for Alzheimer's symptoms.
Oddly, the amount of caffeine consumed does not appear to have affected levels of tau protein, which is also known to accumulate increasingly in brain tissue as Alzheimer's symptoms worsen.
Research on caffeine's effect on tau in the brain is limited, although one lab study suggests that it may reduce the chemical activity that causes the protein to "tangle" into toxic clumps. However, it is not clear whether this occurs in cases of Alzheimer's disease. The latest study is based only on a snapshot of caffeine intake habits among a few hundred older individuals, so it says little about how morning coffee in youth or middle age might affect the onset of dementia later on.
When and how caffeine is consumed must be taken into account. Drinking it late in the day, for example, can affect sleep, which also seems to affect long-term neurological functioning. Heavy use of chocolate and energy drinks is associated with extra sugar, which also compromises cognitive health.
Taken together with the growing body of research on the relationship between caffeine and health in general, however, it's safe to say that your morning Earl Grey, afternoon latte, and small afternoon chocolate snack may play a role in keeping your body working for many years to come. | BGNES
