Concurrent use of amphetamine stimulants and antidepressants by undergraduate students

Figures & data

Table 1 Demographic characteristics of stimulant users and nonusers

Characteristic	Users, n (%)	Nonusers, n (%)	χ^2 (P-value)	Use Rx for depression		χ^2 (P-value)
				Users, n (%)	Nonusers, n (%)
Gender			NS			NS
Female	54 (68)	1,338 (71)		12 (80)	78 (92)
Male	25 (32)	559 (29)		3 (20)	7 (8.2)
Race/Ethnicity			12.5 (0.029)
White	70 (89)	1,421 (75)		12 (80)	77 (91)	NSa
Asian	3 (3.8)	185 (9.8)		1 (1.6)	2 (2.4)
Black/African American	0 (0)	132 (7)		0 (0)	0 (0)
Hispanic	2 (2.5)	74 (3.9)		1 (6.7)	3 (3.5)
More than one race	1 (1.2)	49 (2.6)		0 (0)	2 (2.4)
Other	3 (3.8)	36 (1.9)		0 (0)	0 (0)
Class standing			11.22 (0.011)			NSa
Freshman	11 (14)	528 (28)		4 (2.7)	15 (18)
Sophomore	17 (22)	486 (26)		2 (13)	22 (26)
Junior	28 (35)	448 (24)		3 (20)	24 (28)
Senior	22 (28)	433 (23)		6 (40)	24 (28)
Living/residency			39.78 (<0.001)			NSa
Dorm room	39 (49)	1,366 (72)		8 (53)	56 (66)
Off-campus apartment	27 (34)	371 (20)		5 (33)	23 (27)
At home	3 (3.8)	114 (6)		2 (13)	5 (5.9)
Sorority/fraternity	4 (5)	14 (0.7)		0 (0)	0 (0)
Other	5 (6.3)	30 (1.6)		0 (0)	1 (1.2)
No answer	1 (1.2)	2 (0.1)		0 (0)	0 (0)
Group affiliation			NS			NSa
None	24 (30)	514 (27)		8 (53)	20 (24)	0.028b
Sorority/fraternity	16 (20)	252 (13)		1 (6.7)	13 (15)
Club sports team	8 (10)	200 (10)		1 (6.7)	2 (2.4)
Intramural sports team	17 (22)	424 (22)		1 (6.7)	16 (19)
Preprofessional group	21 (27)	499 (26)		2 (13)	23 (27)
Cultural-center group	6 (7.6)	256 (13)		2 (13)	7 (8.2)
Division 1 sports team	3 (3.8)	60 (3.2)		1 (6.7)	6 (7.1)
Music – dance group	4 (5)	187 (9.9)		1 (6.7)	5 (5.9)
Student government	0 (0)	119 (6.3)		0 (0)	9 (11)

Notes:

a Chi-square unreliable as more than 20% of cells had frequencies <5

b Fisher’s exact test.

Abbreviations: NS, nonsignificant; Rx, prescription(s).

Table 2 Lifestyle characteristics of stimulant users and nonusers

Characteristic	Users, n (%)	Nonusers, n (%)	χ^2 (P-value)	Use Rx for depression		χ^2 (P-value)
				Users, n (%)	Nonusers, n (%)
Sleep per night, hours			NS			NSb
Under 5	3 (3.8)	66 (3.5)		2 (13)	1 (1.2)
5–6	33 (42)	748 (39)		6 (40)	34 (40)
7–8	39 (49)	990 (52)		4 (27)	39 (46)
Over 8	4 (5.1)	92 (4.8)		3 (20)	11 (13)
Exercise			NS			NSb
A few times a month	20 (25)	466 (25)		5 (33)	28 (33)
A few times a week	35 (44)	721 (38)		4 (27)	23 (27)
Daily	7 (8.9)	268 (14)		0 (0)	16 (19)
Once a week	4 (5.1)	231 (12)		1 (6.7)	7 (8.2)
Not at all	13 (16)	211 (11)		5 (33)	11 (13)
Alcohol use			23.43 (<0.001)			NSb
Yes	72 (91)	1,143 (60)		11 (73)	59 (69)
No	2 (2.5)	273 (14)		0 (0)	10 (12)
I never drink	5 (6.3)	346 (18)		4 (27)	14 (16)
No answer	0 (0)	135 (7.1)a		0 (0)	2 (2.4)
Tobacco use
Cigarettes or chewing tobacco	33 (42)	392 (21)	<0.001c	0 (0)	13 (15)	NSc
Chewing tobacco	6 (7.6)	23 (1.2)	<0.001c	0 (0)	0 (0)	NSc
None	46 (58)	1,505 (79)		15 (100)	72 (85)
Energy drinks/supplements	4 (5.1)	54 (2.8)	NSc	0 (0)	1 (1.2)	NSc
Sources of medical information			NS			NSb
Family	45 (57)	1,221 (63)		3 (20)	44 (52)
Labels	20 (25)	438 (23)		6 (40)	22 (26)
Friends	12 (15)	277 (15)		3 (20)	3 (3.5)
Primary care provider	7 (8.9)	262 (14)		7 (47)	31 (37)
Magazines	4 (5.1)	40 (2.1)		0 (0)	1 (1.2)
Coach	0 (0)	17 (0.9)		0 (0)	0 (0)

Notes:

a Class standings were: 20% freshman, 17% sophomore, 37% junior, 27% senior.

b Chi-square unreliable as more than 20% of cells had frequencies <5.

c Fisher’s exact test.

Abbreviations: NS, nonsignificant; Rx, prescription(s).

Table 3 Health conditions and symptoms of stimulant users and nonusers

Characteristic	Users, n (%)	Nonusers, n (%)	χ^2 (P-value)	Use Rx for depression		χ^2 (P-value)
				Users, n (%)	Nonusers, n (%)
Health self-report			12.79 (0.005)			NSa
Good/very good	38 (48)	1,213 (64)		5 (33)	35 (41)
Average	22 (28)	459 (24)		5 (33)	33 (39)
Fair	15 (19)	174 (9.2)		3 (20)	10 (12)
Poor	4 (5.1)	49 (2.6)		2 (13)	7 (8.2)
No answer	0 (0)	2 (0.1)		0 (0)	0 (0)
Health conditions in the last yearc			NS			NSa
Anxiety	40 (51)	436 (23)		14 (93)	69 (81)
Depressiond	24 (32)	239 (13)		13 (87)	63 (74)
Asthma	10 (13)	236 (12)		0 (0)	9 (11)
Irregular heartbeat	4 (5.1)	68 (3.6)		2 (13)	3 (3.5)
High blood pressure	2 (2.5)	42 (2.2)		0 (0)	0 (0)
High cholesterol	1 (1.3)	51 (2.7)		0 (0)	0 (0)
Health symptoms in the past month			300.3 (<0.001)			NSa
Headache	58 (73)	1,216 (64)		14 (93)	64 (75)
Difficulty sleeping	52 (66)	717 (38)		13 (87)	44 (52)	0.012b
Fatigue	52 (66)	856 (45)		11 (73)	55 (65)
Difficulty concentrating	46 (58)	647 (34)		11 (73)	45 (53)
Cough	41 (52)	793 (42)		6 (40)	32 (38)
Cold	38 (48)	1,078 (57)		6 (40)	42 (49)
Pain	36 (46)	703 (37)		9 (60)	37 (44)
Diarrhea	31 (39)	422 (22)		9 (60)	20 (24)
Depression	26 (33)d	253 (13)		9 (60)	50 (59)
Dizziness	26 (33)	290 (15)		6 (40)	18 (21)
Nicotine craving	25 (32)	62 (3.3)		6 (40)	4 (4.7)	<0.001b
Weight gain	17 (22)	306 (16)		4 (27)	18 (21)
Weight loss	11 (14)	210 (11)		2 (13)	12 (14)
Unsteadiness	11 (14)	107 (5.6)		2 (13)	5 (5.9)
Constipation	10 (13)	222 (12)		3 (20)	15 (18)
Skin change	10 (13)	130 (6.8)		2 (13)	7 (8.2)
Memory change	9 (11)	72 (3.8)		2 (13)	5 (5.9)
Vision changes	7 (8.9)	90 (4.7)		1 (6.7)	6 (7.1)
Bladder problems	7 (8.9)	103 (5.4)		2 (13)	6 (7.1)
Falls or near fall	4 (5.1)	73 (3.8)		2 (14)	4 (4.7)
Taste/smell change	3 (3.8)	30 (1.6)		0 (0)	0 (0)
Prescription/OTC pain-reliever use	51 (65)	983 (52)	0.026b	12 (80)	41 (48)	0.027b
Prescription pain-reliever use	6 (7.6)	54 (2.8)	<0.001b	1 (6.7)	5 (5.9)	NSb
Prescription for depression	15 (19)e	77 (4.1)	<0.001b	15 (100)e	85 (100)

Notes:

a Chi-square unreliable as more than 20% of cells had frequencies <5

b Fisher’s exact test

c Other conditions with frequencies <2% were: arthritis, blood clots in the legs, cancer, diabetes, kidney disease, low thyroid, ulcer

d Concurrent medications used for depression were reported by eleven (48%) users reporting symptoms of depression; of these, two were nonprescription

e Medications prescribed for depression reported were: SSRIs (9), SSRI/SNRI (1), Wellbutrin (bupropion; 2), lithium (1), Mirapex^® (pramipexole; 1), Trileptal^® (oxcarbazepine; 1).

Abbreviations: NS, nonsignificant; OTC, over the counter; Rx, prescription(s); SNRI, serotonin–norepinephrine reuptake inhibitor; SSRI, selective serotonin reuptake inhibitor.

Table 4 Binary logistic regression model (additive) predicting stimulant use among those taking prescription medication for depression

Predictor	Coefficient	SE coefficient	Z	P-value	Odds ratio	95% CI
						Lower	Upper
Constant	−4.37379	1.03028	−4.25	0.000
No group affiliation	1.36867	0.704357	1.94	0.052	3.93	0.99	15.63
Difficulty sleeping	1.69038	0.880265	1.92	0.055	5.42	0.97	30.44
Nicotine craving	2.14449	0.798576	2.69	0.007	8.54	1.78	40.84
Rx/OTC pain-reliever use	0.806254	0.762883	1.06	0.291	2.24	0.50	9.99

Notes: Log-likelihood −30.705. Test that all slopes are zero: G=22.804, df=4, P-value=0.000.

Abbreviations: CI, confidence interval; df, degrees of freedom; OTC, over the counter; Rx, prescription; SE, standard error.

Table 5 Goodness-of-fit tests

Method	Chi-square	df	P-value
Pearson	8.94813	7	0.256
Deviance	9.82565	7	0.199
Hosmer–Lemeshow	3.74996	4	0.441

Abbreviation: df, degrees of freedom.

Table 6 Binary logistic regression statistics for predictors of user status among respondents taking prescription medication for depression, final model

Predictor	Coefficient	SE coefficient	Z	P-value	Odds ratio	95% CI
						Lower	Upper
Constant	−2.69485	0.483689	−5.57	0.000
No group affiliation	1.33104	0.644333	2.07	0.039	3.78	1.07	13.38
Nicotine craving	2.61942	0.775016	3.38	0.001	13.73	3.01	62.70

Notes: Log-likelihood –33.733. Test that all slopes are zero: G=16.749, df=2, P-value=0.000.

Abbreviations: CI, confidence interval; df, degrees of freedom; SE, standard error.

Table 7 Goodness-of-fit tests

Method	Chi-square	df	P-value
Pearson	0.0336663	1	0.854
Deviance	0.0331446	1	0.856
Hosmer–Lemeshow	0.0066045	1	0.935
Brown:
General alternative	0.0336629	2	0.983
Symmetric alternative	0.0321470	1	0.858

Abbreviation: df, degrees of freedom.