The relationship between cognitive reserve and outcome after controlling for psychological status and sex following mild traumatic brain injury

Figures & data

Table 1. Background demographic details and injury characteristics.

Background Variable (n = 94)	Frequency (%)
Age (years) Mean (sd) Range	37.05 (14.01) 18–60
Sex	75.5% Male; 24.5% Female
Education (years) Mean (sd) Range	13.37 (2.31) 10–19
Premorbid IQ Mean (sd) Range	105.8 (9.50) 81–124
Psychological Distress Index Mean (sd) Range	29.24 (22.92) 0.75–95.00
Employment Status Full-time work Part-time work Not working	54.3% 17% 28.7%
Occupation Professionals Managers Technicians/Trade Community/Personal Clerical/Admin Sales Machinery Labourers Students	22.4% 17% 20.3% 5.3% 7.4% 5.3% 2.1% 7.4% 12.8%
Involved in litigation	11%
Drug use history None Occasional past Class A drug use Current Class B drug use	95.7% 3.2% 2.1%
Alcohol use (drinks/week)
None	22.3%
<2	26.6%
3–10	36.2%
11–20	13.8
<35	1.1%
Injury Descriptor	Frequency (%)
Days since injury Mean (sd) Range	60.72 (10.61) 37–85
Injury cause MVA MBA Cycling Fall Sport Other	19.1% 12.8% 27.7% 21.3% 7.4% 11.7%
GCS Mean (sd) 13 14 15	14.55 (.67) 9.7% 25.8% 64.5%
LOC None <5 min 5–10 min 10–30 min	10.6% 75.6% 5.3% 7.4%
PTA <1 min 1–5 mins 5–60 mins 1–6 hours 6–12 hours 12–24 hours	32.9% 24.6% 15.9% 8.5% 8.5% 9.6%

Note: MVA: Motor vehicle accident; MBA: Motorbike accident; GCS: Glasgow Coma Scale score; LOC: Loss of consciousness; PTA: Post traumatic amnesia.

Table 2. Bivariate correlations between background variables, cognitive reserve variables, and measures of symptom reporting.

Background and Cognitive Reserve Variables	Measures of Symptom Reporting
	RPQ	CCAMCHI
Age (years)	−.193	−.138
Sex (0=F; 1=M)	−.357***	−.194
Psychological Distress	.684***	.534***
Education (years)	−.223*	−.256*
Occupation (lower vs. higher)	−.297**	−.181
Pre-morbid IQ	−.194	−.063

Note: Occupation (lower vs. higher): categorized on the basis of occupational cognitive demand; RPQ: Rivermead Post Concussion Symptoms Questionnaire; CCAMCHI: Cognitive Complaint after Mild Closed Head Injury questionnaire; *=<.05; **=<.01; ***=<.001.

Table 3. Model significance of each linear regression model for RPQ and CCAMCHI.

DV	IVs Steps 1 & 2	IV Step 3	F	p	Step 1 Adj R^2	Step 2 Adj R^2	R^2 Δ	Step 3 Adj R^2	R^2 Δ
RPQ	S1: Age, Sex, Litigation S2: Psych Distress	Education	14.795	<.001	.200	.425	.224***	.437	.018
	S1: Age, Sex, Litigation S2: Psych Distress	Occupation	16.656	<.001	.151	.425	.271***	.418	.001
	S1: Age, Sex, Litigation S2: Psych Distress	Pre-morbid IQ	12.318	<.001	.189	.404	.214***	.397	.000
CCAMCHI	S1: Age, Sex S2: Psych Distress	Education	4.034	.003	.019	.189	.175**	.197	.021
	S1: Age, Sex S2: Psych Distress	Occupation	3.664	.007	−.017	.214	.233***	.201	.003
	S1: Age, Sex S2: Psych Distress	Pre-morbid IQ	3.643	.006	.019	.189	.175**	.176	.001

Note: RPQ: Rivermead Post Concussion Symptoms Questionnaire; CCAMCHI: Cognitive Complaint after Mild Closed Head Injury questionnaire; **=<.01; ***=<.001.

Table 4. Parameters for Model 3 of each hierarchical linear regression model for RPQ and CCAMCHI by cognitive reserve variable.

Dependent variable	Independent variable	b	SE B	b	p-value
RPQ	Age	.006	.009	.059	.509
	Sex	−.737	.298	−.217	.015
	Litigation	.634	.391	.135	.108
	Psychological Distress	.036	.006	.535	<.001
	Education	−.093	.056	−.144	.100
	Age	.008	.011	.073	.446
	Sex	−.345	.336	−.098	.308
	Litigation	.736	.420	.158	.084
	Psychological Distress	.040	.007	.594	<.001
	Occupation	−.120	.293	−.040	.682
	Age	.000	.010	−.004	.969
	Sex	−.652	.306	−.193	.036
	Litigation	.654	.410	.142	.115
	Psychological Distress	.035	.006	.530	<.001
	Pre-morbid IQ	−.001	.015	−.009	.922
CCAMCHI	Age	.000	.000	.046	.726
	Sex	−.010	.007	−.162	.172
	Psychological Distress	.001	.000	.440	.001
	Education	−.002	.001	−.158	.214
	Age	.000	.000	.060	.665
	Sex	−.001	.008	−.022	.865
	Psychological Distress	.001	.000	.514	<.001
	Occupation	−.003	.006	−.059	.660
	Age	.000	.000	−.029	.826
	Sex	−.009	.007	−.145	.225
	Psychological Distress	.001	.000	.452	.001
	Pre-morbid IQ	.000	.000	.040	.755

Note: RPQ: Rivermead Post Concussion Symptoms Questionnaire; CCAMCHI: Cognitive Complaint after Mild Closed Head Injury questionnaire.