A pilot study of cognitive training with and without transcranial direct current stimulation to improve cognition in older persons with HIV-related cognitive impairment

Figures & data

Table 1 Description of participants

Age (years)	Gender	Education (years)	Race	Condition	Completion status	Viral loada (copies/mL)	ln loada (natural log of copies/mL)	CD4 (cells/mm^3)	CD4 per cent
46	Male	12	African American	tDCS	Completed	25	1.4	841	40.0
57	Male	9	African American	tDCS	Completed	0	0	605	20.0
49	Female	10	African American	Not randomized	Withdrew	35	1.54	350	18.0
59	Male	11	African American	Not randomized	Withdrew	0	0	907	30.0
49	Female	6	African American	Sham	Completed	97,040	4.987	169	14.1
44	Female	9	African American	Sham	Withdrew	0	0	726	33.0
51	Male	12	African American	Sham	Completed	93,129	4.97	394	20.0
54	Male	12	African American	tDCS	Completed	0	0	443	16.4
46	Male	15	African American	tDCS	Completed	27,060	4.432	471	24.8
51	Male	10	White	Sham	Completed	50	1.699	840	52.5
51	Male	12	White	Sham	Completed	0	0	309	6.0
50	Male	12	African American	tDCS	Completed	0	0	499	27.7
62	Female	11	African American	Sham	Completed	62	1.79	798	30.0
49	Male	12	African American	tDCS	Completed	0	0	811	42.0

Notes:

a Viral loads reported as “undetectable” (<20 copies/mL) are listed as 0; the ln load for undetectable is listed as 0.

Abbreviation: tDCS, transcranial direct current stimulation.

Table 2 Test and self-report data

Treatment	N	Baseline		Follow-up
		Mean	SD	Mean	SD
Digit Span forward (number correct)
Sham	5	7.00	1.73	8.80	1.64
tDCS	6	8.67	1.63	8.83	2.32
Digit Span backward (number correct)
Sham	5	6.20	1.79	7.20	0.84
tDCS	6	6.33	1.21	7.17	2.56
Digit Span sequencing (number correct)
Sham	5	6.60	3.36	7.00	2.65
tDCS	6	7.33	1.63	8.00	3.03
Digit Span scaled score
Sham	5	6.20	3.27	7.80	1.64
tDCS	6	7.33	2.07	11.67	10.86
HVLT-R total (number correct)
Sham	5	15.60	4.56	19.20	6.61
tDCS	6	20.00	4.15	22.17	3.31
HVLT-R delayed recall (number correct)
Sham	5	5.60	2.70	6.80	2.39
tDCS	6	5.17	2.14	7.50	2.26
HVLT-R recognition (number correct)
Sham	5	9.00	4.53	10.40	0.89
tDCS	6	8.17	3.66	9.33	1.51
Trails A (seconds)
Sham	5	14.40	64.33	33.00	9.41
tDCS	6	35.33	9.09	34.17	9.87
Trails B (seconds)
Sham	5	112.00	32.84	100.00	46.24
tDCS	6	97.33	22.43	84.67	24.04
Pegs dominant hand (seconds)
Sham	5	98.60	16.59	115.60	51.15
tDCS	6	94.83	18.57	90.00	13.04
Pegs nondominant hand (seconds)
Sham	5	155.80	86.97	154.00	83.35
tDCS	6	108.33	24.65	101.50	24.35
PAOF language (average rating)
Sham	5	2.36	0.81	1.80	0.44
tDCS	6	2.57	0.47	2.37	0.41
PAOF motor/sensory perceptual (average rating)
Sham	5	2.60	0.45	2.16	0.67
tDCS	6	2.33	0.56	1.97	0.59
PAOF cognitive/intellectual (average rating)
Sham	5	2.07	0.89	1.51	0.40
tDCS	6	2.28	0.71	1.80	0.29
PAOF memory (average rating)
Sham	5	2.76	1.07	2.08	0.31
tDCS	6	2.77	0.82	2.25	0.55
PAOF total (average rating)
Sham	5	2.45	0.72	1.89	0.23
tDCS	6	2.49	0.35	2.10	0.13
CESD (total score)
Sham	5	15.20	3.96	10.20	3.27
tDCS	6	22.50	8.26	20.33	9.97

Notes: Digit Span forward, backward, sequencing: WAIS-IV subtests; Trails A and B: Trail Making Test, Parts A and B; Pegs dominant and nondominant: Grooved Pegboard test, dominant and nondominant hands time.

Abbreviations: SD, standard deviation; tDCS, transcranial direct current stimulation; HVLT-R, Hopkins Verbal Learning Test, Revised; PAOF, Patient’s Assessment of Own Functioning; CESD, Center for Epidemiological Studies Depression scale; WAIS-IV, Wechsler Adult Intelligence Scale, 4th edition.

Figure 1 HVLT-R total by group and time.

Abbreviations: HVLT-R, Hopkins Verbal Learning Test-Revised; tDCS, transcranial direct current stimulation.

Figure 2 Grooved Pegboard dominant hand by group and time.

Abbreviation: tDCS, transcranial direct current stimulation.

Figure 3 PAOF by group and time.

Abbreviations: PAOF, Patients Assessment of Own Functioning; tDCS, transcranial direct current stimulation.

Table 3 Effect sizes for the interaction of group by time

	η^2	d	P-value
Digit Span forward	0.12	0.73	0.51
Digit Span backward	0.43	1.74	0.16
Digit Span backward with change in CESD	0.77	3.63	0.12
Digit Span sequencing	0.55	2.22	0.09
Digit Span sequencing with change in CESD	0.98	13.04	0.01
Digit Span scaled score	0.26	1.18	0.31
HVLT-R total	0.16	0.88	0.43
HVLT-R delayed	0.82	2.58	0.06
HVLT-R recognition	0.21	1.02	0.36
Trails A	0.64	−2.66a	0.11
Trails B	0.15	0.84	0.45
Pegs dominant	0.12	0.75	0.50
Pegs nondominant	0.16	0.96	0.43
PAOF total	0.36	1.50	0.28
PAOF total with change in CESD	0.15	0.83	0.62
CESD	0.22	1.07	0.42

Notes: Digit Span forward, backward, sequencing: WAIS-IV subtests; Trails A and B: Trail Making Test, Parts A and B; Pegs dominant and nondominant: Grooved Pegboard test, dominant and nondominant hands time.

a Interaction effect in favor of sham group performance. Bold value was significant after inclusion of change in CESD scale as a covariate.

Abbreviations: CESD, Center for Epidemiological Studies Depression scale; HVLT-R, Hopkins Verbal Learning Test, Revised; PAOF, Patient’s Assessment of Own Functioning; WAIS-IV, Wechsler Adult Intelligence Scale, 4th edition.

Table S1 Nonparametric correlations (Spearman’s rho) for covariates, treatment, and outcomes

	Gender	Education	Race	In load	CD4	Treatment	Digit Span	HVLT-R total	HVLT-R delayed	Trails A	Trails B	Grooved Pegboard dominant hand
Age	0.19	−0.44	−0.15	−0.24	−0.07	−0.32	0.55	0.00	0.26	−0.26	0.08	0.08
Gender		−0.57	0.22	0.55	−0.22	−0.52	−0.61	−0.68	−0.53	0.52	0.67	0.15
Education			0.12	−0.18	−0.01	0.44	0.08	0.30	−0.15	0.08	−0.54	0.12
Race				0.16	0.00	0.52	−0.34	−0.04	−0.45	−0.04	0.41	−0.26
ln load					−0.25	−0.54	−0.57	−0.42	−0.18	0.06	0.32	0.02
CD4						0.35	−0.18	0.13	0.41	0.48	0.25	0.06
Treatment							0.15	0.38	−0.09	−0.18	−0.26	−0.14
Digit Span								0.54	0.48	−0.79	−0.67	−0.07
HVLT-R total									0.64	−0.37	−0.32	−0.23
HVLT-R delayed										−0.34	−0.14	−0.19
Trails A											0.53	0.23
Trails B												−0.15

Note: Values in bold, P<0.05.

Abbreviation: HVLT-R, Hopkins Verbal Learning Test-Revised.