Psychopharmacol Bull 1998; 34 (3): 391–397
Itil TM, Eralp E, Ahmed I, Kunitz A, Itil KZ
New York Institute for Medical Research,
Tarrytown 10591, USA
In 1994, a standardized dry extract of Ginkgo biloba leaves
(SeGb), has been approved by German health authorities for
the treatment of primary degenerative dementia and vascular
dementia. More than 24 different brands of Ginkgo biloba
extract are sold in the United
States. Tacrine, also known as tetrahydroaminoacrine (THA),
and donepezil are currently the only drugs approved in the
United States for the treatment of Alzheimer's disease.
Previous studies demonstrated that SeGb and tacrine induce
significant pharmacological effects on the brains of young,
healthy human males, as determined by bioelectrical activity
measurements obtained using the quantitative pharmaco-
electroencephalogram (QPEEG) method. The type of central
nervous system (CNS) effects we have seen on
computer-analyzed EEGs (CEEGs) after administration of
tacrine or EGb suggests both are "cognitive activators"
which are, as a class of products, characterized by a
(prepost) relative increase of 7.5 to 13 Hz ("alpha") and
decrease of 1.3 to 7.5 Hz ("delta" and "theta") activity.
To determine whether EGb or tacrine had noticeable
pharmacological effects on elderly subjects diagnosed with
possible or probable Alzheimer's, the present open,
uncontrolled trial was conducted. Data from 18 subjects (11
males, 7 females) at an average age of 67.4 years with light
to moderate dementia (Mini Mental mean score = 23.7, ranges:
15-29 [Geriatric Depression Scale mean scores = 3.7; range:
3.2-5.4]) were analyzed for this presentation.
Each subject was randomly administered a single oral "Test-Dose"
of either 40 mg of tacrine or 240 mg of EGb2 in two separate
sessions within 3- to 7-day intervals. Before drug
administration and at 1- and 3-hour intervals after drug
administration, CEEGs were recorded for a minimum of 10
minutes. The CEEGs were analyzed using Period Analysis
programs we developed for QPEEG.
The results indicated that
both EGb and, to a lesser degree, tacrine induced
pharmacological effects, as established by QPEEG
measurements, in the CNS similar to those previously
established in healthy, young subjects. The type of CNS
effects produced by EGb (as established by HZI's CEEG
psychotropic drug database) in elderly dementia patients
were similar to those induced by tacrine responders as well
as those seen after the administration of other "cognitive
activators" (pramiracetam, vinpocetine, BMY-21502,
suloctidil, and lisuride) and anti-dementia drugs approved
in the United States or Europe (tacrine, donepezil,
nimodipine, piracetam, and oxiracetam) from our database.
The results also showed that 240 mg of EGb has typical
cognitive activator CEEG profiles (responders) in more
subjects (8 of 18) than 40 mg tacrine (3 of 18 subjects).
Because of the small sample size, we could not test the
hypothesis that subjects who showed cognitive activator-type
pharmacological response to the first Test- Dose of EGb or
tacrine also exhibit more therapeutic effects (compared to
nonresponders) when drugs are administered chronically.