Vitamins that may be helpful
Several clinical trials have found that
acetyl-L-carnitine supplementation delays the progression of Alzheimer’s
disease,12 improves memory,13 14 15 and enhances
overall performance in some people with Alzheimer’s disease.16 17
However, in one double-blind trial, people who received acetyl-L-carnitine (1 gram three times
per day) deteriorated at the same rate as those given a placebo.18 Overall,
however, most short-term studies have shown clinical benefits, and most long-term studies (one
year) have shown a reduction in the rate of deterioration.19 A typical supplemental
amount is 1 gram taken three times per day.
In a preliminary study, people who used
antioxidant supplements (vitamin C or vitamin E) had a lower risk of Alzheimer’s
disease compared with people who did not take antioxidants.20 Other preliminary
research shows that higher blood levels of vitamin E correlate with better brain functioning
in middle-aged and older adults.21 The possible protective effect of antioxidants
may be explained by the observation that oxidative damage appears to play a role in the
development of dementia.22 Large amounts of supplemental vitamin E may slow the
progression of Alzheimer’s disease. A double-blind trial found that 2,000 IU of vitamin
E per day for two years extended the length of time people with moderate Alzheimer’s
disease were able to continue caring for themselves (e.g., bathing, dressing, and other
necessary daily functions), compared with people taking a placebo.23
Vitamin B1 is involved in nerve
transmission in parts of the brain (called cholinergic neurons) that deteriorate in
Alzheimer’s disease.24 25 The activity of vitamin B1-dependent
enzymes has been found to be lower in the brains of people with Alzheimer’s
disease.26 It has therefore been suggested that vitamin B1 supplementation could
slow the progression of Alzheimer’s disease. Two double-blind trials have reported small
but significant improvements of mental function in people with Alzheimer’s disease who
took 3 grams a day of vitamin B1, compared to those who took placebo.27
28 However, another double-blind trial using the same amount for a year found no effect
on mental function.29
Phosphatidylserine (PS), which is related
to lecithin, is a naturally occurring compound
present in the brain. Although it is not a cure, 100 mg of PS taken three times per day has
been shown to improve mental function, such as the ability to remember names and to recall the
location of frequently misplaced objects, in people with Alzheimer’s
disease.30 However, subsequent studies have not validated these results. In one
double-blind trial, only the most seriously impaired participants received benefits from
taking PS; people with moderate Alzheimer’s disease did not experience significant
improvements in cognitive function.31 In another double-blind trial, people with
Alzheimer’s disease who took 300 mg of PS per day for eight weeks had better improvement
in overall well-being than those who took placebo, but there were no significant differences
in mental function tests.32 In another double-blind trial, 200 mg of PS taken twice
daily produced short-term improvements in mental function (after six to eight weeks), but
these effects faded toward the end of the six-month study period.33
The PS used in these studies was obtained from bovine brain phospholipids. A plant source
of PS is also available. However, the chemical structure of the plant form of PS differs from
the bovine form. In a preliminary study, plant-derived PS was no more effective than a placebo
at improving the memory of elderly people.34 Soy-derived PS was also ineffective in
a double-blind study of elderly people with
age-related cognitive decline.35
A double-blind trial of 20 to 25 grams per day of lecithin failed to produce improvements in mental
function in people with Alzheimer’s disease.36 However, there were
improvements in a subgroup of people who did not fully comply with the program, suggesting
that lower amounts of lecithin may possibly be helpful. Lecithin supplementation has also been
studied in combination with a cholinesterase inhibitor drug called tacrine, with predominantly negative
results.37 38 39 40
In a double-blind trial, supplementing with the fatty acids present in fish oil (0.6 grams per day of EPA and 1.7 grams per
day of DHA) for six months was not beneficial in people with Alzheimer's disease. However, in
the subgroup of people with very mild cognitive impairment, supplementation with these fatty
acids slowed the rate of cognitive decline compared with a placebo.41
DMAE (2-dimethylaminoethanol) may increase
levels of the brain neurotransmitter acetylcholine. In one preliminary trial, people with
senile dementia were given DMAE supplements of 600 mg three times per day for four weeks. The
participants did not show any changes in memory, though some did show positive behavior
changes.42 However, a subsequent double-blind trial found no significant benefit
from DMAE supplementation in people with Alzheimer’s disease.43
In a preliminary report, two people with a hereditary form of Alzheimer’s disease
received daily: coenzyme Q10 (60 mg), iron (150 mg of sodium ferrous citrate), and vitamin B6 (180 mg). Mental status improved in both
patients, and one became almost normal after six months.44
Studies in the test tube have shown that
zinc can cause biochemical changes associated with Alzheimer’s disease.45
For that reason, some scientists have been concerned that zinc supplements might promote the
development of this disease. However, in a study of four people with Alzheimer’s
disease, supplementation with zinc (30 mg per day) actually resulted in improved mental
function.46 In a recent review article, one of the leading zinc researchers
concluded that zinc does not cause or worsen Alzheimer’s disease.47
A small, preliminary trial showed that oral
NADH (10 mg per day) improved mental function in people with Alzheimer’s
disease.48 Further studies are necessary to confirm these early results.
Some researchers have found an association between Alzheimer’s disease and
deficiencies of vitamin B12 and folic acid;49 50 however, other
researchers consider such deficiencies to be of only minor importance.51 In a study
of elderly Canadians, those with low blood levels of folate were more likely to have dementia
of all types, including Alzheimer’s disease, than those with higher levels of
folate.52 Little is known about whether supplementation with either vitamin would
significantly help people with this disease. Nonetheless, it makes sense for people with
Alzheimer’s disease to be medically tested for vitamin B12 and folate deficiencies and
to be treated if they are deficient.
Most,53 54 55 56 but not all,57
58 studies have found that people with Alzheimer’s disease have lower blood
DHEA levels than do people without the
condition. Emerging evidence suggests a possible benefit of DHEA supplementation in people
with Alzheimer’s disease. In one double-blind trial, participants who took 50 mg twice
daily for six months had significantly better mental performance at the three-month mark than
those taking placebo. At six months, statistically significant differences between the two
groups were not seen, but results still favored DHEA.59 In another clinical trial,
massive amounts of DHEA (1,600 mg per day for four weeks) failed to improve mental function or
mood in elderly people with or without Alzheimer’s disease.60 It is likely
that the amount of DHEA used in this trial was far in excess of an appropriate amount,
illustrating that more is not always better.
Are there any side effects or interactions?
Refer to the individual supplement for information about any side effects or interactions.
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