The Standardized Field Sobriety Tests (SFST) and measures of cognitive functioning.

OBJECTIVE: The Standardized Field Sobriety Tests (SFST) are utilised widely to assess fitness to drive when law enforcement suspects a driver's ability to drive is impaired, whether by drugs or alcohol. The SFST ostensibly achieve this through assessment of the level of drivers' cognitive and psychomotor impairment, although no studies have explicitly assessed the relatedness of cognitive ability and performance on the SFST. The current study aimed to assess the relationship between the three components of the SFST with a well validated computerised cognitive battery. METHOD: A sub-set of 61 placebo condition participants comprised the sample, with 33 females and 28 males (mean age 25.45 years). Correlations between the individual SFST subscales 'Horizontal Gaze Nystagmus' (HGN), the 'One Leg Stand' (OLS) and the 'Walk and Turn' test (WAT) and Cognitive Drug Research (CDR) sub-scales of 'Quality of Working Memory', 'Power of Attention' and 'Continuity of Attention' were analysed using point-biserial correlation. RESULTS: Sixty participants were included for analyses. A weak-moderate positive (five subscales) and a moderate-strong negative (two subscales) association was noted between seven of the nine individual CDR subscales and the SFST subscale of the WAT test (all p<0.05). Individually, a moderate positive association was noted between the sub-scale 'Nystagmus lack of smooth pursuit' and 'digit vigilance reaction time' and 'choice reaction time; reaction time' (both p<0.05) and 'Nystagmus head move and/or jerk' and 'simple reaction time' (p<0.001). When assessed as a partially composite factor, a comparable association was also noted between the composite score of the SFST subscale 'Nystagmus head move and/or jerk' and both (a) simple and (b) digit vigilance reaction time (both p<0.05). No association was noted between any of the individual cognitive variables and the SFST subscale 'OLS', or between composite cognitive scores 'Quality of Working Memory', 'Power of Attention' and 'Continuity of Attention' and total SFST scores. DISCUSSION: Variation in some aspects of cognitive performance was found to be moderately and positively correlated with some individual aspects of the SFST; particularly among tasks which assess reaction time. Impairment of these cognitive processes can also contribute to the completion of complex tasks such as driving or the SFST. Complex behavioural tasks such as driving are often severely impaired due to intoxication, and thus in a practical sense, the SFST can still be considered a useful screening tool to identify drug or alcohol impaired drivers.

An examination of the validity of the standardized field sobriety test in detecting drug impairment using data from the Drug Evaluation and Classification program.

OBJECTIVE: The purpose of this study is to assess the validity of the 3 components of the Standardized Field Sobriety Test (SFST), including the Horizontal Gaze Nystagmus (HGN), One Leg Stand (OLS), and Walk and Turn (WAT) tests, in identifying impairment among suspected drug-impaired drivers using data recorded during drug evaluation and classification (DEC) evaluations. METHODS: Data from 2142 completed DEC evaluations of central nervous system (CNS) stimulants, CNS depressants, narcotic analgesics, cannabis, or no drugs were analyzed using multinomial logistic regression. RESULTS: All drug categories were significantly associated with impaired performance. On the HGN, users of CNS depressants were significantly more likely to experience lack of smooth pursuit and distinct nystagmus at maximum deviation compared to non-drug users. On the OLS, users of all drug classes were significantly more likely to sway while balancing and use their arms to maintain balance but significantly less likely to hop compared to drug-free cases. Users of CNS depressants, CNS stimulants, and narcotic analgesics were significantly more likely to put their raised foot down during the test. On the WAT, users of CNS depressants, CNS stimulants, and narcotic analgesics were significantly less likely to keep their balance while listening to test instructions compared to those who had not used drugs. Users of CNS depressants were less likely to touch heel-to-toe while walking, whereas individuals who had used narcotic analgesics were less likely to take the correct number of steps. CONCLUSIONS: These findings provide support for the use of the SFST as a screening tool for law enforcement to identify impairment in persons who have used CNS stimulants, CNS depressants, cannabis, or narcotic analgesics.

Simplifying the process for identifying drug combinations by drug recognition experts.

OBJECTIVE: The purpose of this study is to statistically identify the set of drug-related cues from Drug Evaluation and Classification (DEC) evaluations that significantly predict the categories of drugs used by suspected drug-impaired drivers. METHODS: Data from 819 completed Canadian DEC evaluations of combinations of central nervous system (CNS) stimulants with cannabis, CNS stimulants with narcotic analgesics, cannabis with alcohol, and no-drug cases were analyzed using a multinomial logistic regression procedure. RESULTS: Eleven clinical indicators from the DEC evaluations significantly enhanced the prediction of drugs used by suspected drug-impaired drivers, including condition of the eyes, lack of convergence, rebound dilation, reaction to light, mean pulse rate, presence of visible injection sites, performance on the Horizontal Gaze Nystagmus Test, pupil size in darkness, performance on the One-Leg Stand Test, muscle tone, and performance on the Walk-and-Turn Test. CONCLUSIONS: The findings from this study will facilitate the process of identifying the correct categories of drugs ingested by suspected drug-impaired drivers by focusing on critical signs and symptoms of drug influence. This work will have direct and immediate relevance to the training of drug recognition experts (DREs) by providing the foundation for an innovative, statistically based approach to drug classification decisions by DREs. This research will also facilitate the enforcement of drug-impaired driving laws in Canada to help make Canadian roadways safer for all.

A meta-analytic review of school-based prevention for cannabis use.

This investigation used meta-analytic techniques to evaluate the effectiveness of school-based prevention programming in reducing cannabis use among youth aged 12 to 19. It summarized the results from 15 studies published in peer-reviewed journals since 1999 and identified features that influenced program effectiveness. The results from the set of 15 studies indicated that these school-based programs had a positive impact on reducing students' cannabis use (d = 0.58, CI: 0.55, 0.62) compared to control conditions. Findings revealed that programs incorporating elements of several prevention models were significantly more effective than were those based on only a social influence model. Programs that were longer in duration (≥15 sessions) and facilitated by individuals other than teachers in an interactive manner also yielded stronger effects. The results also suggested that programs targeting high school students were more effective than were those aimed at middle-school students. Implications for school-based prevention programming are discussed.

Toward a more parsimonious approach to drug recognition expert evaluations.

OBJECTIVE: The purpose of this study is to statistically identify the set of drug-related cues from Drug Evaluation and Classification (DEC) evaluations that significantly predict the substance used by suspected drug-impaired drivers. METHODS: Data from 742 completed Canadian DEC evaluations of central nervous system (CNS) stimulant, narcotic analgesic, and cannabis cases were analyzed using a multinomial logistic regression procedure. RESULTS: Nine clinical indicators from the DEC evaluations significantly enhanced the prediction of drug category, including pulse rate, condition of the eyes and eyelids, lack of convergence, hippus, reaction to light, rebound dilation, systolic blood pressure, and the presence of injection sites. CONCLUSIONS: The findings from this study will facilitate the process of identifying the correct category of drug ingested by focusing on critical signs and symptoms of drug influence. This work will have direct and immediate relevance to the training of drug recognition experts (DREs) by providing the foundation for an innovative, statistically based approach to drug classification decisions by DREs.