Researchers from the Neuromodulation Research Facility at the Butler Hospital in Providence, Rhode Island, analyzed brain signals associated with learning and lodging memories in 20 individuals, uncovering surprising details challenging assumptions that caffeine promotes plasticity.
“These preliminary data highlight a need to directly test the effects of caffeine in prospective well-powered studies, because in theory, they suggest that chronic caffeine use could limit learning or plasticity,” write the researchers in their published paper.
Thanks to its ability to block adenosine, a signaling chemical in the brain which helps us feel sleepy at the right time, caffeine has a reputation for giving us an alertness boost.
Adenosine also affects a process called long-term potentiation (LTP), which in simple terms is how the neuron cells in the brain strengthen connections between themselves – thought to be crucial in the brain taking on new information and adapting over time.
A total of 16 people who drank between one and five caffeinated drinks a day and four people who barely touched caffeine were subjected to a brain stimulation process designed to mimic a readiness to learn in the brain, called repetitive transcranial magnetic stimulation or rTMS.
The team then looked for signs of electrical impulses in the nervous system as a way of measuring LTP. In those who didn’t drink caffeinated drinks, these LTP effects appeared to be significantly stronger.
According to the researchers, regular stimulation from caffeine may be causing a counteracting effect in the brain, which might explain the lower levels of plasticity – but this is just a hypothesis for the time being.
There are caveats here: only 20 people took part in this research, and the caffeine/non-caffeine split was heavily weighted. The review also relied on self-reported caffeine dosages, which means the researchers can’t know how different doses of caffeinated drinks actually impact long-term potentiation.
That said, the review was a pilot investigation intended to inform future hypotheses. The researchers intend to investigate further with precise and well-controlled future studies where the timing of the caffeine intake and its dose is strictly regulated before testing. This, the authors say, would lend “a better estimate of central nervous system bioavailability and correlation with plasticity responses.”
The relationship between caffeine and health is already rather complicated: it’s been shown to have both positive and negative effects in previous research, from potentially protecting against dementia to perhaps increasing diabetes risk.
“A better understanding of how caffeine alters the underlying mechanism of learning and memory, as well as the potential impact of caffeine on clinical rTMS effects, merits further attention,” write the researchers.
The research has been published in Frontiers in Psychiatry.
Watafiti kutoka Kituo cha Utafiti wa Neuromodulation katika Hospitali ya Butler huko Providence, Rhode Island, walichambua ishara za ubongo zinazohusiana na kujifunza na kumbukumbu za kukodisha katika watu 20 na kufunua maelezo ya kushangaza yanayopinga dhana kwamba kafeini huendeleza plastiki. "Hii data ya awali inaangazia haja ya moja kwa moja kupima athari za caffeine katika utafiti wa baadaye wenye nguvu, kwa sababu kwa nadharia, zinaonyesha kwamba matumizi ya muda mrefu ya caffeine inaweza kupunguza kujifunza au plasticity, "waandishi wa watafiti katika karatasi yao iliyochapishwa. " Kwa sababu ya uwezo wake wa kuzuia adenosine, kemikali ya ishara katika ubongo ambayo hutusaidia kuhisi usingizi wakati unaofaa, caffeine ina sifa ya kutupa mwongozo wa tahadhari. Adenosine pia huathiri mchakato unaoitwa uwezo wa muda mrefu (LTP), ambayo kwa maneno rahisi ni jinsi seli za neva katika ubongo zinaimarisha uhusiano kati yao - inayofikiriwa kuwa muhimu katika ubongo kuchukua habari mpya na kukabiliana na wakati. Watu 16 waliokunywa kinywaji kimoja hadi vitano vya kahawa kwa siku na watu wanne ambao hawakuchukua kahawa kwa urahisi walifanyiwa mchakato wa kuchochea ubongo ulioundwa kuiga utayari wa kujifunza katika ubongo, unaoitwa uchochezi wa magnetic ya transcranial ya kurudia. Watafiti hao walichunguza ishara za umeme katika mfumo wa neva ili kujua kiwango cha LTP. Katika wale ambao hawakunywa vinywaji vyenye kafeini, athari hizi za LTP zilionekana kuwa na nguvu zaidi. Kulingana na watafiti, kuchochea mara kwa mara kutoka kwa kafeini kunaweza kusababisha athari ya kukabiliana katika ubongo, ambayo inaweza kuelezea viwango vya chini vya plasticity - lakini hii ni nadharia tu kwa sasa. Kwa kweli, kuna baadhi ya mapungufu katika utafiti huu, lakini kwa sababu ya idadi ya watu waliohusika katika utafiti huo, tofauti ya caffeine na non-caffeine ilikuwa kubwa. Uchunguzi huo pia ulitegemea vipimo vya kafeini vilivyoripotiwa na watu wenyewe, ambayo inamaanisha watafiti hawawezi kujua jinsi vipimo tofauti vya vinywaji vyenye kafeini vinavyoathiri uwezo wa muda mrefu. Hiyo ilisema, ukaguzi huo ulikuwa uchunguzi wa majaribio uliokusudiwa kuelimisha nadharia za baadaye. Watafiti wana nia ya kuchunguza zaidi na masomo ya baadaye sahihi na kudhibitiwa vizuri ambapo wakati wa ulaji wa caffeine na kipimo chake umepangwa kwa ukali kabla ya kupima. Hii, waandishi wanasema, ingetoa "takwimu bora ya bioavailability ya mfumo wa neva wa kati na uhusiano na majibu ya plasticity." uhusiano kati ya caffeine na afya tayari ni badala ngumu: imeonyeshwa kuwa na athari zote mbili chanya na hasi katika utafiti wa awali, kutoka uwezekano wa kulinda dhidi ya dementia kwa labda kuongeza hatari ya kisukari. "Ufahamu bora wa jinsi caffeine inabadilisha utaratibu wa msingi wa kujifunza na kumbukumbu, pamoja na athari ya uwezekano wa caffeine juu ya athari za kliniki za rTMS, inastahili uangalifu zaidi, "waandishi wa watafiti. Utafiti huo umechapishwa katika Frontiers in Psychiatry.