A daily cup of coffee in the morning can help get you going and stay focused, but changing your habits by consuming more coffee over time could raise your risk of mild cognitive impairment, says new research from scientists in Italy. The study, co-authored by Dr. Vincenzo Solfrizzi of the University of Bari Aldo Moro in Italy, involved 1,445 individuals recruited from 5,632 subjects, aged 65-84 year old, from the Italian Longitudinal Study on Aging (ILSA).
Mild cognitive impairment (MCI) is an early stage of Alzheimer’s disease (AD) and dementia. No useful treatment exists for altering the natural history of this neurodegenerative disorder, so identification, and then management, of risk factors may be critical for prevention of MCI and its progression to AD and dementia.
In addition to the short-term effects of caffeine, some studies which looked at the long-term effects on brain function have shown evidence that coffee, tea, or caffeine consumption or higher plasma caffeine levels may be protective against cognitive impairment and dementia, with some important exceptions.
This new study found that cognitively normal older people who changed their habits by increasing, over time, their amount of coffee consumption (> 1 cup of coffee/day), had about two times higher rates of MCI compared to those with lowered habits (< 1 cup of coffee/day) and about one and half time higher rate of MCI in comparison with those with constant habits (neither more nor less 1 coffee/day).
Neuroprotective Effects of Coffee
Furthermore, those who habitually drunk moderate amount of coffee (1 or 2 cups of coffee/day) had a reduced rate of the incidence of MCI than those who habitually never or rarely consumed coffee. No significant association was verified between who habitually consumed higher levels of coffee consumption (> 2 cups of coffee/day) and the incidence of MCI in comparison with those who never or rarely consumed coffee.
Researchers Vincenzo Solfrizzi, MD, PhD, and Francesco Panza, MD, PhD, University of Bari Aldo Moro, said:
“These findings from the Italian Longitudinal Study on Aging suggested that cognitively normal older individuals who never or rarely consumed coffee and those who increased their coffee consumption habits had a higher risk of developing MCI. Therefore, moderate and regular coffee consumption may have neuroprotective effects also against MCI confirming previous studies on the long-term protective effects of coffee, tea, or caffeine consumption and plasma levels of caffeine against cognitive decline and dementia.”
The authors put forward different potential mechanisms which may explain the neuroprotective effects of coffee consumption observed in this study.
In one theory, the long-term neuroprotective effect of caffeine may stem from competitive antagonism of excessive activation of adenosine A2A receptors (A2ARs), which may attenuate damage caused by beta-amyloid (A-beta), the toxic peptide accumulating in AD brains. Indeed, both acute or long-term caffeine administration were shown to reduce brain A-beta levels in AD transgenic mice and memory restoration and reversal of AD pathology in mice with pre-existing A-beta burden.
Adenosine is a neuromodulator that operates via the most abundant inhibitory adenosine A1 receptors (A1Rs) and the less abundant, but widespread, facilitatory A2ARs. A1Rs play a key role in neuroprotection, decreasing glutamate release and hyperpolarizing neurons, and their activation attenuates brain damage, whereas their blockade exacerbates damage in adult animals.
The authors concluded:
“More sensitive outcomes such as findings from neuroimaging studies should become available from experimental data, so further explaining the mechanisms underlying the neuroprotective effects of coffee, tea, and caffeine consumption. Larger studies with longer follow-up periods should be encouraged, addressing other potential bias and confounding sources, so hopefully opening new ways for diet-related prevention of dementia and AD.”