Methamphetamine use parameters do not predict neuropsychological impairment in currently abstinent dependent adults

Abstract

Methamphetamine (meth) abuse is increasingly of public health concern and has been associated with neurocognitive dysfunction. Some previous studies have been hampered by background differences between meth users and comparison subjects, as well as unknown HIV and hepatitis C (HCV) status, which can also affect brain functioning. We compared the neurocognitive functioning of 54 meth dependent (METH+) study participants who had been abstinent for an average of 129 days, to that of 46 demographically comparable control subjects (METH-) with similar level of education and reading ability. All participants were free of HIV and HCV infection. The METH+ group exhibited higher rates of neuropsychological impairment in most areas tested. Among meth users, neuropsychologically normal (n=32) and impaired (n=22) subjects did not differ with respect to self-reported age at first use, total years of use, route of consumption, or length of abstinence. Those with motor impairment had significantly greater meth use in the past year, but impairment in cognitive domains was unrelated to meth exposure. The apparent lack of correspondence between substance use parameters and cognitive impairment suggests the need for further study of individual differences in vulnerability to the neurotoxic effects of methamphetamine.

An Evaluation of the Evidence that Methamphetamine Abuse Causes Cognitive Decline in Humans

“…Rather, it is possible that binge episodes differentially contribute to cognitive decline, perhaps particularly in individuals who have not yet developed considerable tolerance to the drug (Segal et al, 2003). Cherner et al (2010b) did not find a relationship between cognitive function and binge patterns in MAdependent humans, but to our knowledge, this is the only study to have examined this issue.…”

“…To our knowledge, only one study has examined the relationship between parameters of MA use and cognitive function in a primary analysis. In that study (Cherner et al, 2010b), parameters of MA use for MA-dependent participants who were cognitively impaired (at least mild impairment in two or more cognitive domains based on demographically adjusted norms) were compared with those of MA-dependent participants who were not impaired on a comprehensive cognitive battery. The results revealed that the cognitively impaired and non-impaired groups did not differ on any index of MA use, including years of use, lifetime grams consumed, average grams used per year, length of abstinence, method of administration, bingeing pattern, or age of initiation.…”

“…Given that MA exposure does not appear to be linearly related to cognitive function in humans, but animal studies and other sources of data do suggest that MA causes cognitive decline in some individuals, authors have suggested that other factors may moderate the relationship between MA exposure and cognitive decline (Cherner et al, 2010b;Dean and London, 2010). Moderating variables may also help to explain variability in the cognitive performance of MA-dependent participants.…”

Tobacco may mask poorer episodic memory among young adult cannabis users.

“…Detailed interviews were conducted with each participant to ascertain approximations of cumulative amount of past year cannabis, alcohol and tobacco use. This approach employed modified timeline follow-back procedures, similar to methods employed in other studies (Cherner et al, 2010; Gonzalez et al, 2012; Rippeth et al, 2004; Schuster et al, 2012), and involved gathering retrospective estimates of amount of daily cannabis (reported in or converted to grams), alcohol (reported in or converted to standard drinks) and tobacco (reported in or converted to cigarettes) use over the year prior to the study visit. Amount of use per substance was summed to arrive at a cumulative estimate of amount of past year consumption.…”

Effect of the environmental enrichment on the severity of psychological dependence and voluntary methamphetamine consumption in methamphetamine withdrawn rats

“…Methamphetamine (METH) is an addictive psychostimulant that dramatically affects the central nervous system (CNS) [7]. Recent findings have shown that chronic METH use alters synaptic plasticity in the brain, which may contribute to its adverse effects [35], include dependence, withdrawal syndrome and drug craving [9,17,34].…”