Biomedical subjects

R McKetin

Publications and source records attributed to R McKetin.

4 recordsLinked to original sources

PubMed1999

Event-related potential indices of auditory selective attention in dependent amphetamine users.

BACKGROUND: The aim of the present study was to further investigate a previously reported attention-related impairment in dependent amphetamine users using event-related potential (ERP) indices of selective attention. METHODS: ERPs were recorded during an auditory selective attention task (SAT) that involved detecting infrequent long-duration target tones presented among short-duration tones that varied in location (left vs. right ear) and pitch (low vs. high). Amphetamine users (n = 19) were divided into two groups, high dependence (n = 10) and low dependence (n = 10), based on amphetamine Severity of Dependence Scale scores, and compared to an age-matched control group (n = 9). RESULTS: The high-dependence group showed slowed reaction time and reduced early processing negativity and peak N1 amplitude to location-relevant nontarget stimuli. Poor performance on the SAT was highly correlated with deficits in early processing, which were also related to poor performance on the Wechsler Memory Scale Attention/Concentration index. CONCLUSIONS: It is suggested that severely dependent users suffer an inability to selectively enhance the sensory processing of relevant auditory information. This may produce poor automatic preferential processing of relevant information and increase load on limited attentional resources.

Adolescent↗

PubMed1999

Changes in auditory selective attention and event-related potentials following oral administration of D-amphetamine in humans.

The effect of d-amphetamine on selective attention in humans was investigated by measuring event-related potentials (ERPs) during a complex auditory selective attention task (CSAT). The CSAT required subjects to make a button press response to infrequent target tones presented amongst tones that varied in pitch (high vs. low), location (left vs. right ear) and duration (51 ms vs. 102 ms). Healthy subjects completed the CSAT under three conditions: placebo, 10 mg and 20 mg d-amphetamine, at least one week apart. D-amphetamine produced a significant dose response increase in hit-rate and decrease in reaction time without changing false alarm rate. D-amphetamine reduced late PN to location irrelevant stimuli and pitch irrelevant stimuli in both the attended and unattended location. The effect of d-amphetamine was interpreted as a decrease in the maintenance of the attentional trace to irrelevant stimuli. However, these changes were accompanied by some evidence of processing of stimulus features in the unattended location. These results suggest that d-amphetamine improves selective attention, and decreases the maintenance of attention to irrelevant stimuli.

Administration, Oral↗

PubMed1998

Attention and memory in illicit amphetamine users: comparison with non-drug-using controls.

The purpose of this study was to clarify the extent of neuropsychological impairment previously found among amphetamine users (McKetin and Mattick, 1997) by comparing them with a non-drug-using control group. Amphetamine users who were classified as low dependence (n = 15) or high dependence (n = 11) according to the severity of dependence scale (SDS) were compared to non-drug-using control subjects (n = 9) on indices of the Wechsler Memory Scale-Revised (WMS-R). Dependent amphetamine users (high dependence group) performed approximately one half of a standard deviation worse than controls on the verbal memory, attention/concentration and delayed recall indices of the WMS-R but amphetamine users who were less dependent (low dependence group) showed no impairment.

Adult↗

PubMed1997

Attention and memory in illicit amphetamine users.

The purpose of this study was to assess cognitive functioning in a group of illicit amphetamine users. A neuropsychological test battery (Wechsler Memory Scale-Revised (WMS-R) and the digit symbol, block design and vocabulary subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the National Adult Reading Test (NART)) was administered to 78 amphetamine users (mean age = 22.5 years; 46 males, 33 females). Severity of amphetamine dependence was found to be associated with poorer performance on both memory and attention/concentration indices of the WMS-R. The relative contribution of amphetamine dependence, concurrent drug use and other drug related factors to neuropsychological functioning are discussed.

Adolescent↗