Higher Levels of Caffeine in Blood May Be Associated With Lower Likelihood of Dementia

July 19, 2013 · Posted in Potential Treatments, Risk Factors · Comment 

older men drinking coffee

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.

Immune Mechanisms Are Important to the Emergence of Defeat Stress–Induced Depressive Behaviors

July 3, 2013 · Posted in Risk Factors · Comment 

Lab mouse

At a recent scientific meeting, researcher Georgia E. Hodes presented evidence that in mice, the immune system may play a role in behaviors that resemble human depression. Repeated social defeat stress (when an intruder mouse is threatened by a larger mouse defending its territory) is often used as a model to study human depression. Animals repeatedly exposed to social defeat stress start to exhibit social avoidance and lose interest in sucrose. Hodes et al. determined that interleukin 6 (IL-6), an inflammatory cytokine, or signaling molecule, secreted into the blood was crucial to these behaviors. When the researchers injected mice with antibodies that block the effects of IL-6, or when they irradiated the mice’s peripheral immune system to prevent the formation of IL-6, the depressive behaviors did not emerge following defeat stress.

Editor’s Note:  There are increasing data that immunological and inflammatory mechanisms play a role in human affective disorders, and these preliminary data raise the possibility that blocking some immune mechanisms more directly in humans could be a novel therapeutic approach to explore in the future.

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