RationaleThe majority of drug abusers are incapable of sustaining abstinence over any length of time. Accumulating evidence has linked intense and involuntary craving, Impulsive decision-making and mood disturbances to risk for relapse. However, little is known about temporal changes of these neuropsychological functions in methamphetamine (METH)-dependent individuals.ObjectivesTo investigate the effect of length of abstinence on decision-making, craving (baseline and cue-induced), and emotional state in METH-addicted individuals.MethodsIn this cross-sectional study, 183 adult METH-dependent patients at an addiction rehabilitation center who were abstinent for 6 days (n = 37), 14 days (n = 33), 1 month (n = 31), 3 months (n = 30), 6 months (n = 26), or 1 year (n = 30) and 39 healthy subjects were administered the Iowa Gambling Task (IGT) to assess decision-making performance. Depression, anxiety, and impulsivity were also examined. One hundred thirty-nine METH abusers who were abstinent for the aforementioned times then underwent a cue session, and subjective and physiological measures were assessed.ResultsMETH dependent individuals who were abstinent for longer periods of time exhibited better decision-making than those who were abstinent for shorter periods of time. And self-reported emotional symptoms improved with abstinence. METH abusers’ ratings of craving decreased with the duration of abstinence, while cue-induced craving increased until 3 months of abstinence and decreased at 6 months and 1 year of abstinence.ConclusionsWe present time-dependent alterations in decision-making, emotional state, and the incubation of cue-induced craving in METH-dependent individuals, which might have significant clinical implications for the prevention of relapse.
Time-dependent increases in cue-induced nicotine and methamphetamine craving during abstinence were recently reported in human drug-dependent individuals. In the present study, we sought to determine whether this 'incubation of craving' phenomenon also occurs in alcoholics. Four groups of 80 inpatient adult male alcoholics were assessed in a single session (between-group design) for cue-induced alcohol craving at 7, 14, 30 and 60 days of abstinence. Another group that included 19 patients was repeatedly tested for cue-induced alcohol craving at the same abstinence days as above. Other psychological and physiological measures were assessed at the four abstinence timepoints. Cue-induced alcohol craving measured with visual analogue scales was the highest at 60 days of abstinence both between and within groups. However, heart rate, blood pressure and skin conductance responses did not differ between abstinent groups. These results provide evidence of the incubation of alcohol craving in humans, extending previous reports with smokers and methamphetamine addicts.
Traditional farming practices suggest that cultivation of a mixture of crop species in the same field through temporal and spatial management may be advantageous in boosting yields and preventing disease, but evidence from large-scale field testing is limited. Increasing crop diversity through intercropping addresses the problem of increasing land utilization and crop productivity. In collaboration with farmers and extension personnel, we tested intercropping of tobacco, maize, sugarcane, potato, wheat and broad bean – either by relay cropping or by mixing crop species based on differences in their heights, and practiced these patterns on 15,302 hectares in ten counties in Yunnan Province, China. The results of observation plots within these areas showed that some combinations increased crop yields for the same season between 33.2 and 84.7% and reached a land equivalent ratio (LER) of between 1.31 and 1.84. This approach can be easily applied in developing countries, which is crucial in face of dwindling arable land and increasing food demand.
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