List, What I conclude from these studies is that you have to have the
gene and elevated herpes simplex virus I(elevated amounts) to develop
Alzheimer's Disease. It certainly looks like an important factor in
the development of the disease.  Linda Forrest's Mom

<1>
Authors
  Lin WR.  Casas I.  Wilcock GK.  Itzhaki RF.
Title
  Neurotropic viruses and Alzheimer's disease: a search for varicella
zoster
  virus DNA by the polymerase chain reaction.
Source
  Journal of Neurology, Neurosurgery & Psychiatry.  62(6):586-9, 1997
Jun.
Abstract
  BACKGROUND: In studies on the possible role of viruses in the
  aetiopathogenesis of Alzheimer's disease, herpes simplex virus type 1
  (HSV1) DNA was detected by the polymerase chain reaction (PCR) in a
high
  proportion of normal elderly people and of patients with Alzheimer's
  disease. The combination of HSV1 and a host factor, the type 4 allele
of
  the gene for apolipoprotein E, is a strong risk factor for the
disease.
  METHODS: Brain specimens were examined for another herpes virus,
varicella
  zoster (VZV), which, like HSV1, is neurotropic, has a predilection for
  residing latently in the peripheral nervous system, and can
reactivate.
  RESULTS: Using primers for sequences in the VZV origin of replication
gene
  or thymidine kinase gene, VZV DNA was not found in any of 24 samples
(18
  HSV1 positive), from 17 patients with Alzheimer's disease, nor in 20
  samples (12 HSV1 positive from 12 aged normal people. Hybridisation of
the
  PCR products with a radiolabelled oligonucleotide probe capable of
  detecting less than 10 copies of the target sequence, confirmed the
  absence of VZV DNA. CONCLUSION: The presence of one neurotropic
  virus--HSV1--and the absence of another--VZV--in aged human brains is
  consistent with a role for HSV1 in the aetiology of Alzheimer's
disease.

<2>
  Itzhaki RF.  Lin WR.  Shang D.  Wilcock GK.  Faragher B.  Jamieson GA.
Title
  Herpes simplex virus type 1 in brain and risk of Alzheimer's disease
[see
  comments].
Source
  Lancet.  349(9047):241-4, 1997 Jan 25.
Abstract
  BACKGROUND: The apolipoprotein E epsilon 4 (APOE-epsilon 4) allele is
a
  risk factor for Alzheimer's disease (AD), but it is neither essential
nor
  sufficient for development of the disease. Other factors-genetic or
  environmental-must therefore have a role. By means of a PCR we have
  detected herpes simplex virus type 1 (HSV1) in latent form in brains
of
  elderly people with and without AD. We have postulated that limited
  reactivation of the virus causes more damage in AD patients than in
  elderly people without AD because of a difference in the hosts. We now
  report the APOE genotypes of AD patients and non-AD sufferers with and
  without HSV1 in brain. METHODS: DNA was extracted from 84 samples of
brain
  from 46 AD patients (39 temporal lobe, 39 frontal lobe, three
hippocampus)
  and from 75 samples of brain from 44 non-AD elderly people (33
temporal
  lobe, 36 frontal lobe, six hippocampus). PCR amplification was used to
  detect HSV1 thymidine kinase gene and the host APOE gene. FINDINGS: By
  multiple logistic regression, the APOE-epsilon 4 allele frequency was
  significantly higher in the patients positive for HSV1 in brain than
in
  the HSV1-negative AD group, the HSV1-positive non-AD group, or the
  HSV1-negative non-AD group (52.8% vs 10.0%, 3.6%, and 6.3%,
respectively).
  The odds ratio for APOE-epsilon 4 in the HSV1-positive AD group
compared
  with HSV1-negative non-AD group was 16.8 (95% CI 3.61-77.8) and in the
  HSV1-negative AD group, 1.67 (0.21-13.4). We also compared APOE
genotypes
  of 40 people who had recurrent cold sores and 33 non-sufferers; the
  APOE-epsilon 4 allele frequencies were 36% and 9%, respectively (p <
  0.0001). INTERPRETATION: These findings suggest that the combination
of
  HSV1 in brain and carriage of an APOE-epsilon 4 allele is a strong
risk
  factor for AD, whereas either of these features alone does not
increase
  the risk of AD. The findings in people with cold sores support our
  hypothesis that APOE-epsilon 4 and HSV1 together are damaging in the
  nervous system.
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