Very interesting. Thanks Ian.
Quoted message said:Quoted message said:Can you site any studies showing neurotoxicity from amphetamines?
IAN: In addition to those John cited, the following is significant since it found years-long
possibly permanent brain damage from *low-dose* amphetamine use for 6 weeks. Here is the Yale
press release followed by the abstract.
yale.edu99 10 26 02.all.htmlOpen ↗
YALE News Release
Yale Study of Long-Term Learning Deficits Resulting From Repeated Amphetamine Exposure Could Help
Drug Abusers
New Haven, Conn. -- Repeated exposure to low-dose amphetamines can cause deficits in cognitive
performance that last for several years after the exposure ends, offering insight into potential
harmful effects of chronic substance abuse in humans, a Yale study has found.
"While previous studies show that acute amphetamine injections can impair cognition, our report is
the first to demonstrate long lasting-over two years-and possibly permanent cognitive deficits
induced by a brief period of intermittent low-dose amphetamine exposure," said Stacy Castner, a
researcher on the study. "This research could also lead to potential treatment of deficits in
former drug abusers as well as potential drug deterrents in adolescents and young adults."
To mimic the "binge/crash" pattern of drug abuse in humans, Castner gave primates twice-daily
injections of chronic amphetamine (AMPH), five days per week for six weeks. The AMPH dose ranged
from 0.1 mg/kg to 1.0 mg/kg and was increased by 0.1 mg/kg every three drug days.
The investigation assessed changes in behavior and videotaped the primates to record behavioral
responses to each dose of AMPH. At six months into the amphetamine exposure, the primates were
tested on an array of cognitive tasks ranging from recognition memory, visual discrimination and
spatial working memory. Primates previously exposed to amphetamines failed to successfully perform
the tasks even with continued testing, for up to one and a half years.
"The results show the presence of profound cognitive deficits in the amphetamine-treated
animals," said Castner, associate research scientist in Neurobiology. "This finding could also
lead to further understanding of other diseases involving dysregulation of the brain's dopamine
neurons." (more)
The study, which will be highlighted at the Society for Neuroscience annual meeting in Miami,
Florida from October 23-28, is consistent with data from human research where commonly abused
drugs such as cocaine and ecstasy have been found to produce long-lasting and possibly permanent
cognitive deficits.
"It may be the case that even a brief period of low-dose amphetamine abuse in early adolescence or
early adulthood can produce profound cognitive deficits that may persist for a couple of years or
more after amphetamine use has ended," said Castner.
The investigators' ongoing research includes experiments involving neurotransmitters that will
help explain the long-lasting cognitive deficits in primates. They are also conducting experiments
to reverse the AMPH-induced cognitive deficits in the same group of primates and they plan to
investigate the biochemical and structural changes in the primate brain that could account for the
behavioral deficits.
This study was supported by the Center for Neuroscience in Mental Disorders from the National
Institutes of Health. Patricia S. Goldman-Rakic, professor of neurobiology at Yale was principal
investigator.
###
Neuropsychopharmacology 2000 Jan;22(1):4-13
Behavioral changes and [123I]IBZM equilibrium SPECT measurement of amphetamine-induced dopamine
release in rhesus monkeys exposed to subchronic amphetamine.
Castner SA, al-Tikriti MS, Baldwin RM, Seibyl JP, Innis RB, Goldman-Rakic PS.
Section of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA.
Previously we have shown that twelve weeks of repeated low-dose d-amphetamine (AMPH) exposure in
rhesus monkeys induces a long-lasting enhancement of behavioral responses to acute low-dose
challenge. The present study was designed to investigate the behavioral and neurochemical
consequences of a six-week regimen of low-dose AMPH exposure (0.1-1.0 mg/kg, i.m., b.i.d.) in
rhesus monkeys. SPECT imaging of AMPH's (0.4 mg/kg) ability to displace [123I]IBZM bound to D2
dopamine receptors in the striatum of saline control and AMPH-treated animals prior to and
following chronic treatment was accomplished using a bolus/constant infusion paradigm. Following
chronic AMPH treatment, all monkeys showed an enhanced behavioral response to acute AMPH challenge
and a significant decrease in the percent of AMPH-induced displacement of [123I]IBZM in striatum
compared to their pretreatment scans. These findings suggest that relatively small changes in
presynaptic dopamine function may be reflected in significant alterations in the behavioral
response to acute AMPH challenge.
PMID: 10633485 [PubMed - indexed for MEDLINE]
ncbi.nlm.nih.govquery.fcgiOpen ↗
=10633485&dopt=Abstract
iangoddard.netjournal.htmOpen ↗
"To lengthen thy life, lessen thy meals." Ben Franklin
Ongoing CR monkey study update: "In the monkeys...those on reduced feeding since the study started
are dying at a rate that is about half that of the monkeys receiving a full food ration."
Associated Press: Eating less may extend human life. August 1, 2002 :
msnbc.com788746.aspOpen ↗
