Catherine P. Domier

Cognitive Impairment in Individuals Currently Using Methamphetamine

Although there are increasing reports of methamphetamine use, studies examining the cognitive consequences of methamphetamine have not been performed on a population currently using the drug. To characterize this population, 65 people currently using MA regularly and 65 non-users were given a battery of cognitive tests. The battery included recall, recognition, Digit Symbol, Trail Making A & B, Stroop, Wisconsin Card Sort, backward digit span, and the FAS test of verbal fluency. The methamphetamine users were significantly more impaired on recall tasks, digit symbol, Stroop color words, and Trail Making B, but scores fell within the normal ranges on the other measures.

Frontoparietal cortical activity of methamphetamine-dependent and comparison subjects performing a delay discounting task.

Relative to individuals who do not have addictive disorders, drug abusers exhibit greater devaluation of rewards as a function of their delay (“delay discounting”). The present study sought to extend this finding to methamphetamine (MA) abusers and to help understand its neural basis. MA abusers (n = 12) and control subjects who did not use illicit drugs (n = 17) participated in tests of delay discounting with hypothetical money rewards. We then used a derived estimate of each individuals delay discounting to generate a functional magnetic resonance imaging probe task consisting of three conditions: “hard choices,” requiring selections between “smaller, sooner” and “larger, later” alternatives that were similarly valued given the individuals delay discounting; “easy choices,” in which alternatives differed dramatically in value; and a “no choice” control condition. MA abusers exhibited more delay discounting than control subjects (P < 0.05). Across groups, the “hard choice > no choice” contrast revealed significant effects in the ventrolateral prefrontal cortex, dorsolateral prefrontal cortex (DLPFC), dorsal anterior cingulate cortex, and areas surrounding the intraparietal sulcus (IPS). With group comparisons limited to these clusters, the “hard choice > easy choice” contrast indicated significant group differences in task‐related activity within the left DLPFC and right IPS; qualitatively similar nonsignificant effects were present in the other clusters tested. Whereas control subjects showed less recruitment associated with easy than with hard choices, MA abusers generally did not. Correlational analysis did not indicate a relationship between this anomaly in frontoparietal recruitment and greater degree of delay discounting exhibited by MA abusers. Therefore, while apparent inefficiency of cortical processing related to decision‐making in MA abusers may contribute to the neural basis of enhanced delay discounting by this population, other factors remain to be identified. Hum. Brain Mapp, 2007.

Cognitive performance of current methamphetamine and cocaine abusers.

Abstract Forty currently using methamphetamine (MA) abusers. 40 currently using cocaine (COC) abusers, and 80 comparison participants who did not use psychostimulants received a cognitive battery and questionnaires covering medical history and stimulant use patterns. Forty comparison participants were matched to the 40 MA users on age. education, ethnicity, and gender. The other 40 comparison participants were matched to the cocaine users on the same variables. This design was chosen because there were significant differences in age and ethnicity between COC and MA users that precluded a direct comparison between the groups. The COC group was older and predominantly African American compared to the predominantly Caucasian MA group. When compared to their matched non-using control groups, both MA and COC abusers were impaired on cognitive measures, but the type and degree of impairments were somewhat different.

Drugs and sexual effects: role of drug type and gender

This study investigated gender differences in the relationship between psychoactive substance use and sexual thoughts, feelings, and behaviors. Participants (N = 464) were male and female alcohol, opiate, cocaine, and methamphetamine users enrolled in an outpatient treatment program at any of 8 sites. A self-report survey that inquired about the specific sexual thoughts, feelings, and behaviors of the participant during previous instances of being under the influence of their primary drug of dependence served as the data source. The results indicate that different categories of psychoactive agents were associated with different effects on sexual behavior, and that those effects vary by gender. Development of a valid measure assessing the type and strength of these relationships may be beneficial for use by treatment programs in promoting abstinence from drug and alcohol use and preventing relapse.

Brain Activity in Cigarette Smokers Performing a Working Memory Task: Effect of Smoking Abstinence

BACKGROUND When nicotine-dependent human subjects abstain from cigarette smoking, they exhibit deficits in working memory. An understanding of the neural substrates of such impairments may help to understand how nicotine affects cognition. Our aim, therefore, was to identify abnormalities in the circuitry that mediates working memory in nicotine-dependent subjects after they initiate abstinence from smoking. METHODS We used blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to study eight smokers while they performed a letter version of the N-Back working memory task under satiety (< or = 1.5 hours abstinence) and abstinence (> or = 14 hours abstinence) conditions. RESULTS Task-related activity in the left dorsal lateral prefrontal cortex (DLPFC) showed a significant interaction between test session (satiety, abstinence) and task load (1-back, 2-back, and 3-back). This interaction reflected the fact that task-related activity in the satiety condition was relatively low during performance of the 1-back task but greater at the more difficult task levels, whereas task-related activity in the abstinence condition was relatively high at the 1-back level and did not increase at the more difficult task levels. CONCLUSIONS We conclude that neural processing related to working memory in the left DLPFC is less efficient during acute abstinence from smoking than at smoking satiety.

A Comparison of Patterns of Methamphetamine and Cocaine Use

Abstract Typical use patterns of methamphetamine (MA) users were examined using self-report measures from 120 MA and 63 cocaine users. Twenty (14 MA and 6 cocaine) of the participants also took part in structured interviews designed to provide more specific descriptions of their drug use. The typical MA user uses more than 20 days a month. Use is evenly spaced throughout the day, and although the amount of drug used per day is not different, MA users use fewer times per day than do cocaine users. Fewer of the cocaine users are continuous users, and they use in the evening rather than the daytime. The cocaine pattern of fewer days of use, evening use, and more frequent doses per day fits a picture of recreational use, whereas the all-day-most-days methamphetamine pattern does not.

Buprenorphine tapering schedule and illicit opioid use

AIMS To compare the effects of a short or long taper schedule after buprenorphine stabilization on participant outcomes as measured by opioid-free urine tests at the end of each taper period. DESIGN This multi-site study sponsored by Clinical Trials Network (CTN, a branch of the US National Institute on Drug Abuse) was conducted from 2003 to 2005 to compare two taper conditions (7 days and 28 days). Data were collected at weekly clinic visits to the end of the taper periods, and at 1-month and 3-month post-taper follow-up visits. SETTING Eleven out-patient treatment programs in 10 US cities. INTERVENTION Non-blinded dosing with Suboxone during the 1-month stabilization phase included 3 weeks of flexible dosing as determined appropriate by the study physicians. A fixed dose was required for the final week before beginning the taper phase. MEASUREMENTS The percentage of participants in each taper group providing urine samples free of illicit opioids at the end of the taper and at follow-up. FINDINGS At the end of the taper, 44% of the 7-day taper group (n = 255) provided opioid-free urine specimens compared to 30% of the 28-day taper group (n = 261; P = 0.0007). There were no differences at the 1-month and 3-month follow-ups (7-day = 18% and 12%; 28-day = 18% and 13%, 1 month and 3 months, respectively). CONCLUSION For individuals terminating buprenorphine pharmacotherapy for opioid dependence, there appears to be no advantage in prolonging the duration of taper.

Gender effects on mood and cigarette craving during early abstinence and resumption of smoking

Women are more likely than men to relapse after initiating abstinence from cigarette smoking. The reasons for this phenomenon are unclear but may relate to negative mood, cigarette craving, or other symptoms of nicotine withdrawal. We addressed this issue in a study of 26 female and 38 male smokers. The Profile of Mood States, Shiffman-Jarvik Withdrawal Scale, and Urge to Smoke Scale were administered twice in each of two test sessions on different days. One session began within 1 hr after smoking ad libitum and the other followed overnight abstinence (>13 hr). On each test day, the two assessment blocks were separated by a 5-10-min break, during which each participant smoked one cigarette. In the first test block, both men and women reported higher scores after >13 hr abstinence than after <1 hr abstinence on the tension-anxiety and anger-hostility subscales of the Profile of Mood States, and for the craving and psychological symptoms of the Shiffman-Jarvik Withdrawal Scale. Scores of female subjects showed significantly larger differences between sessions on the tension-anxiety subscale and a trend toward significance (p = .050) on the anger-hostility subscale of Profile of Mood States than those of males. Moreover, on the tension-anxiety subscale, women also reported a greater reduction than men from smoking one cigarette after overnight abstinence. The findings indicate that overnight abstinence produces more negative mood symptoms and cigarette craving in female smokers than in males, and that resumption of smoking produces greater relief from these symptoms in female smokers. These differences may contribute to the greater likelihood of relapse when women try to quit smoking.

Cognitive deficits among methamphetamine users with attention deficit hyperactivity disorder symptomatology

Abstract Understanding the association between attention deficit hyperactivity disorder (ADHD) and substance abuse, specifically methamphetamine (MA) abuse, is challenging, partly because little is known about the specific constellation of cognitive impairments produced by MA. The present investigation serves to address this relationship by comparing the cognitive performance of MA abusers with ADHD symptomatology (n = 28) and MA abusers without ADHD symptomatology (n = 41) on tests of attention, memory and general intellectual functioning, executive functioning, problem solving, verbal fluency, and abstract thinking. Both MA samples had deficiencies in measures of memory and learning function, psychomotor speed and abstract thinking when compared to a control group (n = 40). Additional deficits were noted on tasks involving executive functioning, attention, and general intellectual functioning in MA abusers with ADHD symptomatology. The preliminary data suggests that executive function deficits and some of the symptoms associated with long-term MA use may be due to the fact that a large proportion of MA addicts had ADHD symptomatology as children.

Effects of cigarette smoking and abstinence on stroop task performance

RationaleSmokers report enhanced concentration after cigarette smoking and difficulty concentrating when abstinent from smoking. These perceived effects may contribute to smoking cessation failures, and if so, clarification of their cognitive bases could inform treatment strategies. Selective attention may be important in this regard, but earlier literature presents inconsistent findings on how smoking abstinence and resumption of smoking influence this cognitive function.ObjectivesWe aimed to compare smokers and nonsmokers on selective attention, and in smokers, to test the effects of overnight abstinence from smoking and of acute smoking on selective attention.Materials and methodsSmokers and nonsmokers (n = 43) performed a Stroop test (two test days, two test blocks per day). Smokers participated after overnight abstinence and also within 1-h of ad libitum smoking. Smokers each smoked a cigarette between test blocks on each day; nonsmokers did not.ResultsSmokers demonstrated longer response latencies for both congruent and incongruent stimuli after overnight than brief abstinence, but no deficit specifically related to selective attention. Whereas nonsmokers showed no changes in performance in the second test block, smoking between blocks reduced the Stroop effect when smokers were abstinent overnight.ConclusionsThese data are consistent with the hypothesis that abstinence from smoking among nicotine-dependent individuals has deleterious effects on cognitive performance, but do not indicate that selective attention is adversely effected. Improvement in selective attention after terminating abstinence with one cigarette may also contribute to smokers’ perceived enhanced ability to concentrate after smoking.