3 - Alcohol and alcohol withdrawal
Berman et al. (1992) investigated the effects, in
laboratory rats, of prenatal exposure to alcohol and
found increased thresholds for eliciting auditory
brainstem responses (ABR evoked potentials) [1].
Susceptibility to audiogenic seizures was not
increased, except that some aspects of seizure
activity were displayed with repeat testing with
acoustic stimuli. This finding may illustrate possible
impairment as opposed to full expression of seizure
disorder.
Faingold and Riaz (1995) investigated the
relationship of alcohol and alcohol withdrawal to
audiogenic seizures [2]. They recorded the firing of
neurons in the inferior colliculus of laboratory rats
before, during, and after administration of alcohol.
Alcohol decreased spontaneous firing of neurons in
the inferior colliculus, and the response of neurons to
high intensity sound stimuli. After withdrawal of
alcohol spontaneous firing of inferior colliculus
neurons increased and firing was significantly
increased with even low level sound stimuli. The
animals also were all susceptible to audiogenic
seizures during withdrawal, and they were agitated
and irritable when handled.
Faingold and Riaz compared the reduction in
neuronal firing to that obtained in other experiments
with known facilitators of gamma-aminobutyric acid
(GABA), including barbiturates. GABA is thought to
be a transmitter within inhibitory neurons, neurons
that prevent firing of primary sensory neurons to
every stimulus presented to the system. Chronic
facilitation of GABA neurons, however, could lead to
desensitization of their normal receptors. Withdrawal
of alcohol then would lead to a diminished capacity
for GABA neurons to act as inhibitors.
GABA neurons could possibly be compared to control
chips in computer systems that set or defer attention
signals for multiple devices interacting over a
particular communication channel. If every signal
sets an attention flag, ordered communication among
the input components breaks down and the system
becomes non-functional. As in computer systems,
some means must exist that prioritizes the order in
which simultaneously presented stimuli of different
frequency and intensity are transmitted to areas of
the brain that process auditory information.
Faingold (1999) implanted electrodes in normal and
one strain of genetically epilepsy-prone rats [3].
Seizures in response to auditory stimuli were then
followed. Lower threshold of response by inhibitory
neurons in the inferior colliculus appears to allow a
seizure to develop and spread to the cerebral cortex.
Anticonvulsant drugs that inhibit re-uptake of
gamma-aminobutyric acid (GABA) reduced firing of
neurons in the inferior colliculus, strengthening the
case that GABA is the inhibitory neurotransmitter that
modulates neuronal response in the inferior colliculi
to acoustic stimuli.
Alcohol affects the auditory system, and can cause
auditory hallucinations. Prenatal exposure to alcohol
has been associated with autism in some cases, and
understanding how the brain might be impaired by
alcohol may be relevant for the impairment in children
with autism due to other causes [4-9]. Research on
how the brain is affected by alcohol should be
followed for clues it might yield on neurological
dysfunction in autism.
- Berman RF, Beare DJ, Church MW, Abel EL (1992) Audiogenic seizure
susceptibility and auditory brainstem responses in rats prenatally exposed to
alcohol. Alcoholism, Clinical and Experimental Research 16:490-498.8-258.
- Faingold CL, Riaz A (1995) Ethanol withdrawal induces increased firing in
inferior colliculus neurons associated with audiogenic seizure susceptibility.
Experimental Neurology 132:91-98.
- Faingold CL. (1999) Neuronal networks in the genetically epilepsy-prone rat.
Advances in Neurology. 1999;79:311-21.
- Nanson JL (1992) Autism in fetal alcohol syndrome: a report of six cases.
Alcoholism, Clinical and Experimental Research 16:558-565.
- Harris SR, MacKay LL, Osborn JA (1995) Autistic behaviors in offspring of
mothers abusing alcohol and other drugs: a series of case reports.
Alcoholism, Clinical and Experimental Research 19:660-5
- Aronson M, Hagberg B, Gillberg C (1997) Attention deficits and autistic
spectrum problems in children exposed to alcohol during gestation: a follow-
up study. Developmental Medicine and Child Neurology 39:583-7.
- Fombonne E. (2002) Is exposure to alcohol during pregnancy a risk factor for
autism? J Autism Dev Disord. 2002 Jun;32(3):243.
- Miles JH, Takahashi TN, Haber A, Hadden L (2003) Autism families with a
high incidence of alcoholism. J Autism Dev Disord. 2003 Aug;33(4):403-15.
- Kielinen M, Rantala H, Timonen E, Linna SL, Moilanen I (2004) Associated
medical disorders and disabilities in children with autistic disorder: a
population-based study. Autism. 2004 Mar;8(1):49-60.
- Berman RF et al. (1992)
Audiogenic seizure
susceptibility and auditory
brainstem responses in rats
prenatally exposed to alcohol.
- Faingold CL, Riaz A (1995)
Ethanol withdrawal induces
increased firing in inferior
colliculus neurons associated
with audiogenic seizure
susceptibility.
- Faingold CL. (1999) Neuronal
networks in the genetically
epilepsy-prone rat.
- Nanson JL (1992) Autism in
fetal alcohol syndrome: a
report of six cases.
- Harris SR et al. (1995) Autistic
behaviors in offspring of
mothers abusing alcohol and
other drugs: a series of case
reports.
- Aronson M et al. (1997)
Attention deficits and autistic
spectrum problems in children
exposed to alcohol during
gestation: a follow-up study.
- Fombonne E. (2002) Is
exposure to alcohol during
pregnancy a risk factor for
autism?
- Miles JH et al. (2003) Autism
families with a high incidence
of alcoholism.
- Kielinen M et al. (2004)
Associated medical disorders
and disabilities in children
with autistic disorder: a
population-based study.