PharmacoNutrition Reviewed

Source: Neuroscience Letters 439 (2008): 208-211
Article Type: Original Research
Authors: Kushida S et al.

In their latest paper, Kushida and colleagues examined in Amyloid beta-infused rats the effect of soft-diet feeding on two parameters which are typically affected in Alzheimer’s Disease (AD) patients

a) the release of the neurotransmitter dopamine
b) the learning ability and memory performance

Rats were fed either a hard (standard) or soft diet for 3 weeks days. During the last 2 weeks, rat brains were continuously infused with Abeta, the putative main culprit in AD.

“We found no significant differences in the basal level of dopamine release in the hippocampus between soft- and hard-diet-fed groups; however, the dopamine release evoked by high-K Ringer’s solution was significantly different between the soft- and hard-diet-fed groups. The increase of dopamine release in the hard-diet-fed group reached 420%; however, that in the soft-diet-fed group reached only 260%. In AD model rats, dopamine release in the soft-diet-fed group was significantly less than that of the hard-diet-fed group.”

After assessing the rats in the co-called step-through passive avoidance test, the authors conclude that:

“Our results also suggest that soft-diet feeding impairs learning ability and memory in AD rats; however, the underlying mechanism is unknown. One possible explanation is that the present results may be caused by the changes of activity in sensori-motor pathways of soft-diet-fed rats.”

How does this now relate to AD patients?

“Elderly people lose many teeth as they age. The loss of teeth not only forces them to eat soft foods, but also correlates to the development of senile dementia and Alzheimer’s disease (AD).”

So might one speculate that a rather early move in life towards the consumption of soft food triggers the onset of AD? An interesting idea – although much research is needed to establish this link of cause and consequence.

More on AD and diet (i.e. coffee intake) can be found here.

Source: J Neuroinflammation (2008), 5: 12 (open access)
Article Type: Original Research
Authors: X Chen et al.

A morning without coffee is unthinkable for me. And especially during the day in the lab I need the regular ‘perfusion’ with the black gold. A habit, which - based on the latest publication by Chen et al. - might not be that bad at all for me.

One of the earliest symptoms experienced by Alzheimer’s disease (AD) patients is olfactory dysfunction. The olfactory bulb is characterized by an intact blood brain barrier (BBB) that can get disrupted, e.g., when ingesting a high-cholesterol diet.
When testing such a diet (2% cholesterol) in rabbits, Chen et al. found that the daily administration of 3mg caffeine in the drinking water for 12 weeks “blocked high cholesterol diet-induced
* increases in extravasation of IgG and fibrinogen,
* increases in leakage of Evan’s blue dye
* decreases in levels of the tight junction proteins occludin and ZO-1
* increases in astrocytes activation and microglia density where IgG extravasation was present.”

“Our observations that caffeine had no effects on plasma levels of total cholesterol and HDL indicate that caffeine protects against high cholesterol diet-induced disruption of BBB downstream of cholesterol.”

“The protective effects of caffeine against high cholesterol diet-induced increases in BBB disruption might happen at the BBB per se, and the protective effects of caffeine against high cholesterol diet-induced increases in the density of astrocytes and microglia could be an indirect consequence of its protective effects against BBB disruption. On the other hand, it has been shown that caffeine (and adenosine) can regulate neuroinflammation in in vitro models devoid of BBB. Therefore, the protective effects of caffeine against high cholesterol diet induced increases in astrocyte activation and increases in density of microglia might parallel its protective effects against BBB disruption.”

From a practical point of view it is interesting to note that “the dose of caffeine (3 mg/day) used in this study for 3 to 4 kg rabbits is equivalent to an adult human weighing 70-80 kg consuming a single cup of coffee and is far less than the average caffeine consumption in the USA and Canada that is about 200 mg per person per day.”

The provisional PDF can be downloaded here.