Some neuropsychological profiles of cannabis dependent users on long-term abstinence in a rehabilitation centre in Nigeria

The present study examined some neuropsychological profiles of cannabis dependent users on long abstinence in Nigeria. Ninety participants were recruited for the study. Their ages ranged from 27 – 35 years with a mean age of 30.78. Five neuropsychological instruments were used for the study: Symbol Digit Modality Test (SDMT), Digit Symbol Modality Test (DSMT), Trail Making Tests A & B (TMT – A/B), Rey Auditory Verbal Learning Test (RAVLT) and Rivermead Post Concussion Syndrome questionnaire (RPC). The findings of the study showed significant differences on verbal learning; RAVLT Trial 5: F(2,81) = 15.20, RAVLT Total Trial: F(2,81) = 11.06, Delayed verbal memory, F(2,81) = 10.94 all at P ≤ 0.05 level of testing with cannabis users performing worse than the psychiatric and healthy controls. Significant differences were also seen on processing speed: DSMT: F(2,81) = 3.53 with cannabis users performing worse than the healthy control but better than the psychiatric group. Drug users had significant less performance than the healthy control on TMT A; F(2,81) = 8.04 and TMT B; F(2,81) = 7.41 as measures of executive function. Also, drug users had significant worse complaints of somatic, cognitive and emotional symptoms following brain injury as measured by RPC; F(2,81) = 7.11 all at P ≤ 0.05 level of testing. Discussions of the study was based upon long term effects of cannabis use on neuro-cognition even after prolonged abstinence and reasons for the mixed findings surrounding this area of study. Implications of the study were also examined.Keywords: Neuro-cognition, Cannabis Users, Abstinence, Processing Speed, Memor

Processing Speed Mediates Visual Attention in Patients With Remitted Major Depression

Information processing and attention in psychiatric patients have received limited research interests among neuroscientists. This has further limited clinical interventions in neuropsychological areas of psychiatric disorders. The present study was on processing speed and visual attention in patients with remitted major depression (RMD). Forty two participants were recruited for the study. Twenty one (21) of them were patients with RMD while the other 21 were healthy controls (HC). Four instruments were used to assess processing speed (TMT A and TMT B)  and visual attention (Letter Cancellation TaskS (LCT): Coloured and black-white), while the between group quasi experimental design was used. The findings of the study showed significant differences between RMD and HC on time taken to complete TMT A: F(1,35)=11.01, TMT B: F(1,35)15.50; LCT (coloured) F(1,35)=19.04, LCT (Black-white) F1(1,35)=29.65 at p<0.05 level of testing. Similarly the path model analysis showed that TMT B mediates significantly TMT A (overall processing speed) on time taken to complete LCT (Colored): B=0.62, and LCT (Black and White): B=0.77. The discussion of the study centered on the roles of the ability to shift the task in visual attention search and likely tendency that visual search has common neural circuitry pathway with ability to shift task.

Coding of spatio-temporal attributes: the roles of age and enriched environment

Spatio-temporal attributes are the abilities to remember the position and location of objects in space which may include orientation, direction and distance. Such abilities have been studied in neurological impaired samples. However, enough studies on the roles of cognitive reserve like age and environmental enrichment on coding of spatial abilities in normal samples have been understudied. Similarly, preclinical behavioral protocols of working memory for spatial abilities have been equally sparse. The present study was to examine the effects of age and environmental enrichment on coding of spatial abilities in long evan rats. Conversely, the present study further examined the utility of the training protocol used in the study for assessment of spatio-temporal working memory in preclinical trials. Twenty six naive male long evan rats between the ages of 9-21 months, weighing between 200-400g were use for the study. They were divided into 3 groups: enriched young adults, non-enriched young adults and non-enriched older adults. The Royal Institute of Psychologists Maze Box patterned after that described by Olton and Samuelson (1976) was used while the training procedure was adopted from Kesner (1985) model of amnesic study in rats. The findings showed no significant differences among the groups on all trials. However, overall progress in performance showed that enriched young adults continued to improve as the trials progress, while the non-enriched older adults  showed some decrements from the third day of the trial. On the other hand, significant inter-trial correlations were found between each trial per day and total trial per day showing some level of test-retest reliability of the training protocol. Conversely, between trials improvement were found in performance of the subjects each day showing that learning and memory truly took place. The discussions of the study were on the possible reasons for such non significant differences in performance despite contrary past research studies.Keywords: Spatio-temporal, learning, working memory, Long evan rats, radial arm maz