Relationship between reaction time, mental processing speed and motor

speed in individuals with mild to moderate brain injury

Kenneth NK FONG1, PhD, Marko KL CHAN2, BSc, Peggie PK NG2, MSc

1Department of Rehabilitation Sciences, Hong Kong Polytechnic University

2Occupational Therapy Department, Kowloon Hospital, Hospital Authority Hong Kong SAR, China

Introduction

Background

1. Slowness of reaction time and processing speedwere common difficulties for persons with brain injury.

2. Study support trade off between accuracy and time in tasks of people with brain injury. (Geldmacher & Hills,1997)

3. Lack of study to investigate the relationship between reaction time, mental processing speed and motor speed of the people with brain injury.

Background

Why Occupational Therapist concern?Common problem of brain injuryProcessing speed affect the skills acquisition. (Brigman & Cherry, 2002 )Relationship between work/instrumental Activities of Daily Living and processing speed. => Diff. to sustain in job and resume life role.

Aims of Study1. To investigate the relationship between three

domains(mental processing speed, motor speed, and reaction time) in patients with Brain Injury of mild to moderate severity and compare with the normal subjects.

2. To compare the performance in these three domains between patients with Brain Injury and healthy adults.

3. To refine the assessment tools in different aspects

Method20 out-patients (mean age = 35.6, male/ female = 4:1) with mild to moderate brain injury admitted consecutively into Cognitive training Center of the brain injury (Occupational Therapy Department) of Kowloon Hospital were recruited.

16 of them were diagnosed as traumatic head injury while 4 of them had other brain injury diagnoses with similar features.

MethodInclusion criteria:post-onset of brain injury ≥ 6 months and in Rancho’s level ≥ 7ability to follow and understand instructionsno visual or auditory impairmentat least one functional hand (must be the best or dominant hand) and ability to use “mouse”in computer operation.

Method20 healthy subjects (mean age 38.8, male/ female = 1:1) with closely matched age and educational level were selected for the purpose of comparison. All subjects were evaluated by 3 selected measures for domains, namely reaction time, motor speed, and mental processing speed, at a single time point.

Definition:Reaction time (反應時間): Time duration for production of response to stimuli (Incoccia et al., 2004)Mental Processing Speed (訊息處理機能速度):

Time duration to process the mental tasks. Motor Speed (動作速度): Time duration to execute the movement (Ma & Trombly, 2004)

Assessment

Outcome MeasuresOutcome Measures

Bruininks-Oseretsky Test (Subtest 6)

Minnesota Manual Dexterity Test (Placing Test)

Valpar 7 - rate of work & accuracy

Lafayette (Movement Time)

Captain’s Log (Stimulus Reaction Inhibition)

Captain’s Log(Stimulus Reaction Time)Lafayette (Reaction Time)

Captain’s Log (Finger Tapping)

Captain’s Log (Trail Sequence B) -Time & accuracy

Reaction TimeMotor SpeedMental Processing Speed

Mental Processing SpeedCaptain’s Log (Trail Sequence B)

Beginner modeTarget order: OffTask time: 1 - 6 minutesOutcomes:

Average Reaction Time × No. of Correct ResponsesIncorrect Responses

Mental Processing SpeedValpar 7

Dominant & best handOutcomes:

Total time (Rate of work)Number of errors

Motor SpeedLafayette (Movement Timer)

Time from leaving 1stswitch to touching 2ndswitch3 distances between 2 switches (14, 26, 38cm)10 trialsOutcomes:

Average moving time

Operation of Lafayette instrument

Stimulus

Distance travel

Cue delayStimulus selector

Reaction time

Moving time

Initiate cue

1 = 54cm2 = 42cm3 = 14cm

Reaction TimeLafayette (Reaction Timer)

Same physical layout as in test of moving timeTime from stimuli appears to off 1st switch10 TrialsOutcomes:

Average reaction time

Result

Results(1)1. No significant differences were found in age &

education between two groups.2. Significant differences were noted between two

groups in scores of below items:3. Reaction time: Reaction Timer (p = 0.000),

Stimulus Field (p = 0.003)4. Mental Processing speed: Trail Making (p =

0.000), Stimulus Inhibition (p = 0.001), V7 Rate of work (p = 0.000)

5. Motor Speed: Movement Timer (p = 0.001), Minnesota Placing Test ( p = 0.000)

Results(2):Age mental processing speed, reaction time, and motor speed ˊhealthy group × patient group.Nil significant differences between healthy subjects and patients with brain injury in accuracy on complex tasks such as V7. However, the speed is lower than the healthy people. Also, errors in V7 were detected with faster responses in movement timer and reaction timer ˊ patient group × healthy group.

Results (3):Mental processing speed with the reaction time and motor speed ˊhealthy group × patient group.

Trail speed only shows significant relationship with the Valpar 7 but it is not significantly correlate with its error.

Discussion (1)The results substantiated the presence of reduced mental processing speed, motor speed and reaction time separately in patients with mild to moderate grade brain injury than an age-and education-matched comparison group (healthy people).

Discussion(2)

Age was correlated to mental processing speed,reaction time, and motor speed in the healthy group but not noted in the patient group.

Age was not the key factor of the prediction of performance .

Discussion(3)Nil differences between healthy subjects and patients with brain injury in accuracy on complex tasks but the speed is lower.

Patients tended to sacrifice speed of performance to maintain accuracy in the tasks that demanded regulation and programming. This trade-off phenomenon suggested that both accuracy and the time required to perform the task should be evaluated simultaneously.

Discussion(4)Less correlation was noted in the significant correlations among different measures for patients with TBI than for the healthy subjects.Need for separate clinical examination and training in various aspects of subjects.

Discussion(5)Trail Speed was not significantly correlated with the error noted.May be due to:Fair manipulation of ‘mouse’. Reduce sensitivity of ‘mouse’. Limitation of using computer => affect the result during comparison.

Future DirectionStudy on different sensory aspect: Auditory processing is slower than visual processing (Madigan,2000)Study on the training protocol of the processing speed.Study on the generalization to the tasks.

Conclusion:Lack of relationship among mental processing speed, motor speed, and reaction time in patients with mild to moderate grade of Brain Injury.Marked reduction in the above components of the brain injury patients.More comprehensive training and assessments protocols are indicated.

Mental Processing SpeedCaptain’s Log (Stimulus Reaction Inhibition)

Dominant & best handAdvanced8 seconds response time3 seconds inhibition timeDistraction stimuli: OffAuditory stimuli: OffOutcomes:

Average reaction timeInhibition errorsResponse & non-response errors

Motor SpeedCaptain’s Log (Finger Tapping)

Dominant & best hand10 seconds trial10 seconds restOutcomes:

No. of trialsAverage tapping rate per second

Motor SpeedMinnesota Manual Dexterity Test (Placing Test)

Dominant & best handBegin on right Pick up the bottom disk and insert it into the top hole of the board in some column, then pick up the next disk in the column and so on.Outcomes:

Total time of 1 trial

Reaction TimeCaptain’s Log (Stimulus Reaction Time)

Dominant & best handBeginnerDistraction stimuli: OffAuditory stimuli: OffTask time: 1 minuteOutcomes

No. correct responsesAverage reaction timeResponse & non-response errors

Reaction TimeBruininks-Oseretsky Test (Response Speed)

Trials: 2 practice7 recordedOutcomes:

The medium score among 7 scores is the point score

LimitationSmall sample sizeFair internal consistency within the assessments in the same aspect