The Combined Effect of Chronic Cannabis Use and Subconcussive Head Impacts on Brain Health
Condition: Concussion, Mild
MeSH terms: Brain Concussion
Study type: Interventional

Summary: 
      The purpose of this pilot study is to better understand the effects of chronic cannabis (THC)
      use on the neural responses to subconcussive head impacts, as a form of repetitive soccer
      headings. The study is designed to identify the physiological changes of cannabis using
      cohort (THC) and compare it to a nonusing cohort in order to see if the responses to 20
      controlled bouts of soccer headings are exacerbated by the chronic cannabis use, diminished
      to less of a response, or unchanged, through an array of neurologic measures, including
      cognitive function, ocolar-motor function, autonomic function, and blood biomarkers. The
      hypothesis is that repetitive subconcussive head impacts will impair cognitive function in
      worse memory, attention span, and visual and verbal problem solving; this impairment will be
      greater in the chronic cannabis use groups than non-using group. The blood and salivary
      biomarkers neurofilament light (NFL) and glial fibrillary acidic protein (GFAP) will be
      measured in plasma, with the hypothesis that repetitive subconcussive head impacts will
      significantly increase plasma NFL and GFAP level at 24 hours-post heading and decrease by 72
      hours-post heading, while remaining undetectable at 2 hours-post heading; the chronic
      cannabis use groups will see more severe effects on ocular-motor function than the non-using
      group. The study aims to determine the differences in acute effects of subconcussive head
      impacts on eye movement, attention, and language function between chronic cannabis use
      subjects and non-using subjects by evaluating ocular-motor function with near point of
      convergence and King-Devick tests. The hypothesis is that repetitive subconcussive head
      impacts will significantly increase impairments of eye movements, attention, and language
      function, as well as near point of convergence; the chronic cannabis use groups will see more
      severe effects on hampered ocular-motor function than the non-using group. Lastly, there is a
      cold pressor test to assess autonomic nerve function, with the hypothesis that repetitive
      subconcussive head impacts will decrease autonomic nerve function in chronic cannabis use
      patients to a greater degree than non-using subjects.
    

Detailed description: 
      NUMBER OF PEOPLE TAKING PART IN THE STUDY

      We plan to recruit 45 THC using subjects and 45 non-using subjects.

      PROCEDURES FOR THE STUDY

      Participants will be assigned to the THC cannabis user group or the nonuser group based on
      participants' report of past cannabis use. These groups will then be verified using saliva
      and urine tests for cannabis use history.

      The study consists of 4 test sessions during a 4-day period. The 1st day will take
      approximately 4 hours. The 2nd and 4th day will each take approximately 1 hour. Participants
      will not need to do anything on the 3rd day.

        -  The 1st test session takes place right before the soccer heading intervention.

        -  After the 1st test session, participants will then perform 20 soccer headings in 10
           minutes.

        -  The 2nd test session takes place 2h after the intervention.

        -  The 3rd test session takes place approximately 24h after the intervention.

        -  The 4th test session takes place approximately 72h after the intervention.

      During each test session, participants will be asked to complete a paper-pencil questionnaire
      assessing participants' current feeling. The questionnaire consists of 22 possible symptoms
      with 7-point scale to see if participants are experiencing concussion-related symptoms. A
      trained phlebotomist will draw blood from a vein in participants' arm at the four time points
      described in the above bulletpoints. Each 4mL blood sample is equivalent to approximately 1
      teaspoon. A total of approximately 16mL (3-4 teaspoons) will be drawn during this study. The
      researchers will collect saliva samples (2mL) at each time point. Participants will be then
      asked to perform eye-movement tasks with directions from the research assistant. The
      eye-movement tasks consist of watching an object nearing the face (called a convergence test)
      and a brief test that asks participants to name numbers aloud from a screen. These
      eye-movement tasks will be repeated twice and will take about 2 minutes. After eye-movement
      testing, the investigators will ask participants to complete an imPACT test, which is a
      computerized test commonly used to diagnose concussions that measures memory, attention span,
      and visual and verbal problem solving. Completing the imPACT takes 20 to 25min. The last test
      is an autonomic function test, where participants will place participants' hand in a bowl of
      ice water for 60s while participants' heartrate is recorded.

      The first 1st test session is slightly longer than the other two. It requires a saliva
      collection, where participants are asked to collect saliva in his/her mouth for approximately
      15s before spitting onto a test strip. Researchers will need to collect about 7mL (1.5
      teaspoon) of saliva from participants. This test will verify that participants have not used
      cannabis products in the past 72 hours. participants will also be asked for a urine sample. A
      urine sample of approximately 50mL will be used to verify cannabis use history over the past
      3 months.

      During the 1st day, after finishing the 1st test session, participants will perform 20 soccer
      headings. A standard size 5 soccer ball will be projected at 25 mph (equivalent speed to a
      long throw-in) by a JUGS soccer machine, and participants will perform 20 headers with 30
      seconds resting period between each header. participants will be asked to direct the ball
      back towards the JUGS soccer machine in the air.
    

Intervention name(s): Soccer heading
Intervention type(s): Other
Intervention description(s): A standardized and reliable soccer heading protocol will be used for the experiment. A triaxial accelerometer embedded in a head-band pocket and positioned directly below the external occipital protuberance (inion) to monitor linear and rotational head accelerations. A JUGS soccer machine will be used to simulate a soccer throw-in with a standardized ball speed of 25mph. The ball speed is similar to when soccer players make a long throw-in from the sideline to mid-field. Soccer players frequently perform this maneuver during practice and games. Subjects will stand approximately 40ft away from the machine to perform the heading. Participants perform 20 standing headers with 1 header per 30 seconds. The subjects will be instructed to direct the ball back toward the JUGS soccer machine in the air.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Diagnostic
Keywords: soccer heading; subconcussive head impacts; cannabis