History of Illicit Stimulant Use Is Not Associated with Long-Lasting Changes in Learning of Fine Motor Skills in Humans

Prevalence of self-reported movement dysfunction among young adults with a history of ecstasy and methamphetamine use

BACKGROUND

Illicit stimulant use is associated with long-lasting changes in movement and movement-related brain regions. The aim of our study was to investigate the prevalence of movement dysfunction in this population. We hypothesized that prevalence of self-reported movement dysfunction is higher among stimulant users than non-stimulant users.

METHODS

Three groups of adults completed a survey containing questions about demographics, health, drug use, and movement. The groups consisted of ecstasy users with no history of methamphetamine use (ecstasy group, n = 190, 20 ± 3 yrs.), methamphetamine users (methamphetamine group, n = 331, 23 ± 5 yrs.), and non-stimulant users (control group, n = 228, 25 ± 8 yrs.). Movement data was analyzed with logistic regression.

RESULTS

In the unadjusted logistic regression model, group had a significant effect on fine hand control, tremor, and voice/speech questions, but not on other movement domain questions. The prevalence of tremor and abnormal fine hand control was significantly higher in the ecstasy and methamphetamine groups than in the control group (p < 0.018), and changes in voice/speech was more prevalent in the ecstasy group than in the control group (p = 0.015). Age and use of cannabis and hallucinogens were confounding variables. However, inspection of chi-square tables suggests that the effect of these parameters on the movement data is likely to be minor.

CONCLUSIONS

The prevalence of self-reported tremor and changes in fine hand control and voice/speech is significantly higher in stimulant users than in non-stimulant users. Inclusion of these common and noticeable changes in body function may aid public health campaigns that target prevention or harm minimization.

Use of illicit amphetamines is associated with long-lasting changes in hand circuitry and control

OBJECTIVE

The study aim was to determine if use of illicit amphetamines or ecstasy is associated with abnormal excitability of the corticomotoneuronal pathway and manipulation of novel objects with the hand.

METHODS

Three groups of adults aged 18-50 years were investigated: individuals with a history of illicit amphetamine use, individuals with a history of ecstasy use but minimal use of other stimulants, and non-drug users. Transcranial magnetic stimulation was delivered to the motor cortex and the electromyographic response (motor evoked potential; MEP) was recorded from a contralateral hand muscle. Participants also gripped and lifted a novel experimental object consisting of two strain gauges and an accelerometer.

RESULTS

Resting MEP amplitude was larger in the amphetamine group (6M, 6F) than the non-drug and ecstasy groups (p < 0.005) in males but not females. Overestimation of grip force during manipulation of a novel object was observed in the amphetamine group (p = 0.020) but not the ecstasy group.

CONCLUSIONS

History of illicit amphetamine use, in particular methamphetamine, is associated with abnormal motor cortical and/or corticomotoneuronal excitability in males and abnormal manipulation of novel objects in both males and females.

SIGNIFICANCE

Abnormal excitability and hand function is evident months to years after cessation of illicit amphetamine use.

Measuring dexterity in the podiatrist population: a cross-sectional comparison of novice students and experienced podiatrists

BACKGROUND

There is no 'gold-standard' for the evaluation of dexterity for the health professional or podiatrist populations. This has resulted in a broad array of generalised tests to evaluate dexterity. Thus, the aim was to determine which objective generalised dexterity tests are best suited to evaluating dexterity in a podiatry student population.

METHODS

A cohort of Novice podiatry students and Experienced podiatrists were recruited and evaluated on a battery of dexterity tests selected to evaluate a variety of different elements. Group differences were evaluated statistically and regression undertaken on significant test outcomes.

RESULTS

A total of 108 participants were recruited with 54 participants in each of the Novice and Experienced groups. Five of the eight tests were able to discriminate dexterous ability of participants in the Novice and Experienced groups. These included the Grip-lift task, GPT, P-MVC, G-MVC and the AsTex® sensory discrimination test. These tests comprised a total of 11 significant dependent variables (p <  0.05). From the test battery, outcomes were able to predict 79% of the group membership. Age and experience did not explain within-group variability for the Experienced group.

CONCLUSION

Whilst the Experienced group displayed superior performance in strength and speed, the Novice group showed superior coordination and sensory ability. From these findings, we would recommend that outcomes from the Grooved Pegboard Test, Grip-lift task, Grip Strength test and Pinch Grip strength test be used to evaluate elements of dexterity in this population.