Caffeine One of Several Compounds That May Protect Against Dementia
A 2017 article by Yousuf O. Ali and colleagues in the journal Scientific Reports finds that 24 different compounds may boost a brain enzyme that protects against dementia. The enzyme, NMNAT2, protects neurons from stress and combats misfolded proteins called tau that form plaques in the brain as people age.
Ali and colleagues screened 1280 compounds to identify those that might increase NMNAT2 production. Twenty-four of these looked promising, including caffeine and rolipram, an “orphaned drug” once studied as an antidepressant but discontinued in the 1990s. Others with weaker effects on NMNAT2 production included the atypical antipsychotic ziprasidone, cantharidin (a wart-removing substance secreted by blister beetles), fungal metabolite wortmannin, and retinoic acid, a vitamin A derivative. Thirteen of the compounds tested decreased NMNAT2 production.
The researchers followed up the caffeine finding by testing caffeine in mice genetically engineered to produce less NMNAT2. The caffeine administration normalized NMNAT2 production levels in these mice.
Senior researcher Hui-Chen Lu hopes this research will lead to the development of new drugs that can create a chemical blockade against the effects of neurodegenerative illnesses.
Caffeine Improves Memory
In a 2014 study published by Michael A. Yassa et al. in the journal Nature Neuroscience, a 200mg caffeine pill (about the equivalent of a strong cup of coffee) improved long-term recognition memory. One hundred sixty participants who were not regular coffee drinkers were shown a series of 200 pictures, and 24 hours later they were given a surprise test. Compared to participants who received a placebo, those participants who received 200mg of caffeine were better able to discriminate which pictures they had seen before and which ones were new. Participants who received 100mg of caffeine did not show this effect, while those who received 300mg showed the same improvement in memory but also experienced side effects such as headache and nausea.
As long as a cup of coffee does not make its drinker more anxious, it may help boost memory.
Editor’s Note: Coffee may have other benefits. In research collected by the Bipolar Collaborative Network (in which this editor is an investigator), patients who drank coffee were less likely to be overweight. Yassa also believes based on other research that caffeine is associated with a reduced risk for Alzheimer’s disease and that it increases longevity.
Higher Levels of Caffeine in Blood May Be Associated With Lower Likelihood of Dementia
Alzheimer’s disease and other kinds of dementia can be devastating. Researchers are looking for treatments and lifestyle choices that may prevent, slow, or lessen the likelihood of serious dementia. Some epidemiological research in humans and other studies of animals has suggested that consumption of coffee or caffeine may help protect against the development of Alzheimer’s disease. A 2012 study by Arendash et al. published in the Journal of Alzheimer’s Disease sought to clarify the connection between coffee and cognitive status. The researchers also collected data on biomarkers in blood.
In patients with mild cognitive impairment, those patients whose blood levels of caffeine were 1200 ng/mL or higher (an amount that would result from drinking 3–5 cups of coffee daily) did not develop dementia during the following two to four years, while half of those whose blood levels of caffeine were below this threshold did. Moreover, those patients who had mild cognitive impairment at the beginning of the study had lower levels of caffeine than those who had normal cognitive functioning at that time.
Patients with mild cognitive impairment who later developed dementia had low levels of three biomarkers in their blood—the neurotrophic factor granulocyte colony-stimulating factor (G-CSF), the anti-inflammatory cytokine IL-10, and the pro-inflammatory cytokine IL-6. This suggests that low levels of these biomarkers may be an indicator of impending Alzheimer’s disease. G-CSF, in particular, has shown beneficial effects on cognition in mice.
Since half of patients with lower levels of caffeine did not develop dementia, it is clear that caffeine is far from being the only factor that could affect cognitive functioning. Arendash suggested that other factors may include levels of cognitive and physical activity, hypertension (high blood pressure), and antioxidant intake, especially from fruits and vegetables.
Editor’s Note: This study of caffeine was not randomized and is subject to other interpretations. For example, people who drink less coffee may have more hypertension, which is associated with dementia risk. However, the study does raise the possibility that caffeine could have positive effects on the brain (especially if it does not make a patient anxious or insomniac).
The caffeine findings are also supported by studies of dementia in mice. Long-term administration of caffeine to these animals resulted in a similar biomarker profile and prevented cognitive impairment.
Other treatments may also be useful in preventing cognitive decline. In BNN Volume 16, Issue 5 from 2012, we wrote about a one-year prospective study published by Forlenza et al. in the British Journal of Psychiatry in 2011 that showed that lithium at the small dose of 150mg per day reduced the rate of cognitive decline in those with mild cognitive impairment compared to placebo.
