Study - Substance consuption

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Cognitive functioning in substance abuse and

dependence: a population-based study of young adults add_

2656 1558..15681558..1568

Antti Latvala1,2, Anu E. Castaneda1,2, Jonna Perl1, Samuli I. Saarni1, Terhi Aalto-Setl1,3,Jouko Lnnqvist1,4, Jaakko Kaprio1,5, Jaana Suvisaari1,6 & Annamari Tuulio-Henriksson1,2

Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland, 1 Department of Psychology, University

of Helsinki, Finland,2 Department of Child Psychiatry, Hospital for Children and Adolescents, Helsinki University Central Hospital, Finland,3 Department of

Psychiatry, University of Helsinki, Finland,4 Department of Public Health, University of Helsinki, Finland5 and Department of Social Psychiatry,Tampere School of

Public Health, University of Tampere, Finland6

ABSTRACT

Aims To investigate whether substance use disorders (SUDs) are associated with verbal intellectual ability, psycho-motor processing speed, verbal and visual working memory, executive function and verbal learning in young adults,

and to study the associations of SUD characteristics with cognitive performance.Participants A population-based

sample (n = 466) of young Finnish adults aged 2135 years. Measurements Diagnostic assessment was based on all

available information from a structured psychiatric interview (SCID-I) and in- and out-patient medical records. Estab-

lished neuropsychological tests were used in the cognitive assessment. Confounding factors included in the analyses

were comorbid psychiatric disorders and risk factors for SUDs, representing behavioural and affective factors, parental

factors, early initiation of substance use and education-related factors. Findings Adjusted for age and gender, life-

time DSM-IV SUD was associated with poorer verbal intellectual ability, as measured with the Wechsler Adult Intelli-

gence ScaleRevised (WAIS-R) vocabulary subtest, and slower psychomotor processing, as measured with the WAIS-R

digit symbol subtest. Poorer verbal intellectual ability was accounted for by parental and own low basic education,

whereas the association with slower psychomotor processing remained after adjustment for SUD risk factors. Poorer

verbal intellectual ability was related to substance abuse rather than dependence. Other SUD characteristics were notassociated with cognition. Conclusions Poorer verbal intellectual ability and less efficient psychomotor processing are

associated with life-time alcohol and other substance use disorders in young adulthood. Poorer verbal intellectual

ability seems to be related to parental and own low basic education, whereas slower psychomotor processing is

associated with SUD independently of risk factors.

Keywords Abuse, cognition, dependence, population-based sample, substance use disorders, young adults.

Correspondence to:Antti Latvala, Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Mannerheim-

intie 166, FIN-00271, Helsinki, Finland. E-mail: [email protected]

Submitted 23 January 2009; initial review completed 16 April 2009; final version accepted 20 April 2009.

INTRODUCTION

Substance use disorders (SUDs) are characterized by a

maladaptive pattern of substance use leading to clinically

significant impairment or distress. Several studies have

investigated cognitive functioning in people with SUD. In

alcohol use disorders, deficits in executive functions, visu-

ospatial abilities, verbal abilities, learning, memory and

speed of information processing have been observed,

ranging from mild deficits in alcohol abuse and depen-

dence to severe deficits in patients with Korsakoff syn-

drome [1,2]. Impaired cognition has also been reported

in drug use disorders, for example deficits in decision

making and inhibitory cognitive control, reflectingneural

processing in frontal cortical and subcortical areas [3].

Poorer cognitive functioning related to SUDs may

reflect both the effects of long-term heavy substance use

and cognitive differences predating SUD. Heavy use of

alcohol, opioids or stimulants may affect executive and

memory functions [4,5]. On the other hand, poorer gene-

ral intellectual ability is often already observed in SUDs

in adolescence [6]. Also, findings of lower intellectual

RESEARC H REPO RT doi:10.1111/j.1360-0443.2009.02656.x

2009 The Authors. Journal compilation 2009 Society for the Study of Addiction Addiction,104, 15581568


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ability in children at elevated genetic risk for SUD [7]

suggest that lower intellectual ability is unlikely to be

caused by substance use. Indeed, prospective studies have

found lower verbal intellectual ability to increase the risk

for later alcohol problems [8]. Lower intellectualability in

childhood also predicts both lower academic achievement

and illicit drug dependence in adolescence [9].

A necessary strategy for investigating the nature of

the relationship of cognitive deficits with SUD is to take

into account confounding factors that are related to both

SUD and cognitive functioning. Comorbid psychiatric dis-

orders occur commonly with SUDs [10], or precede them

[11]. Psychiatric disorders may be associated with poorer

cognitive functioning and impair later academic and

occupational achievements. Similarly, low educational

level is found consistently in SUDs [12], and educational

achievement is known to overlap with cognitive abilities;

attention and behaviour problems in childhood increase

the risk for SUD [13] but are also associated with poorercognitive and intellectual abilities [14]. Moreover, many

other risk factors for SUDs may have associations with

cognitive performance.

Besides SUD risk factors, several characteristics of SUD

might be relevant for cognitive and intellectual function-

ing. For example, the validity of DSM-IV alcohol depen-

dence and abuse has been under investigation [15], but

whether the type of diagnosis (dependence versus abuse)

is related to cognitive performance is not known.Further-

more, the number of SUD diagnoses during the life-time

and age at SUD onset may reflect the severity of SUD and

thus contribute to the association between SUD and cog-nition. In addition, comparing people with a current SUD

diagnosis with those in remission sheds light on the pos-

sible cognitive deficits related to the state of the disorder.

Both substance use and the incidence of SUDs are

known to peak in young adulthood [16]. Cognitive abili-

ties, in turn, develop through childhood and adolescence,

reaching a stable level by young adulthood [17].

However, the association between SUDs and cognition

among young adults is not well known. Moreover, there

have been very few studies on SUDs and cognition using

general population samples. This paucity may have dis-

torted the current state of knowledge on cognitive func-tioning in SUDs.

In order to address these issues, we used a representa-

tive population-based sample of young Finnish adults to

assess cognitive and verbal intellectual functioning in

alcohol andother substanceuse disorders. AxisI disorders

and several SUD risk factors, representing behavioural

and affective factors, parentalfactors, ageat substanceuse

initiation and educational factors, were included in the

analyses, primarily as confounding factors. Associations

of cognitive and intellectual functioning with character-

istics related to SUD diagnosis were also studied.

METHODS

Sample

The present investigation is part of the Mental Health in

Early Adulthood in Finland (MEAF) study [18]. The

sample was assessed initially in 2001 as part of the

nationwide Health 2000 Survey [10], and re-examined

in the period 200305 in the MEAF study investigating

psychiatric disorders among young adults in Finland.

MEAF was a two-phase study. In the first phase, a ques-

tionnaire was sent to all 1863 members of the study

population, of whom 1316 (71%) returned the question-

naire. In the second phase, respondents who were

screened positive for mental health or substance use

problems and a random sample of people who screened

negative were invited to participate in a mental health

interview and neuropsychological assessment.

The MEAF questionnaire contained scales that

assessed mental health and substance use. A positivescreen for substance use entailed scoring at least three

in the Cut-down, Annoyed, Guilt, Eye-opener (CAGE)

questionnaire [19], or the self-reported use of any illicit

drug at least six times. The CAGE questionnaire, a

widely used screening instrument for alcohol problems,

contains four dichotomous questions assessing problems

related to drinking (need to cut down, annoyed by criti-

cism, feeling guilty, need for an eye-opener). In addition

to screen-positive persons, individuals with hospital

treatment due to any mental or substance use disorder

(ICD chapter V: mental and behavioural disorders)

during the life-time according to the Finnish HospitalDischarge Register were asked to participate. Details of

the sampling and screening procedures have been

reported previously [18]. Participants provided written

informed consent, and the study protocol was approved

by the ethics committees of the National Public Health

Institute and the Hospital District of Helsinki and

Uusimaa.

Diagnostic assessment

Of the 982 individuals invited for psychiatric and neurop-

sychological assessment, 546 (55.6%) participated. Pre-vious analyses indicated that attrition depended on age,

sex and education, but not on mental disorders, psycho-

logical symptoms or substance-use-related problems

reported in the MEAF questionnaire [18]. The psychiatric

interview was conducted by experienced psychiatric

research nurses or psychologists using the Research

Version of the Structured Clinical Interview for DSM-

IV-TR [20]. The Global Assessment of Functioning (GAF)

and the Social and Occupational Functioning Assess-

ment Scale (SOFAS) were also included. All interviews

were reviewed jointly by a psychiatrist and the inter-

Cognition in substance use disorders 1559

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visual span backward, CVLT short delay recall and CVLT

long delay recall, modest ceiling effects were detected

(512% of the observations). Therefore, we used tobit

regression in addition to linear regression to study the

associations between SUD diagnosis and these measures;

no significant changes in the results occurred (data not

shown).

RESULTS

Description of the sample

Both Axis I and personality disorders were more common

in people with SUD (Table 1), while all the selected risk

factors were associated with life-time SUD diagnosis

(Table 2).

Intellectual and cognitive function in SUD

In the first phase of the analyses, the means of cognitive

measures in individuals from the SUD group were found

to be lower (reflecting poorer performance) than in the

no-SUD group in six tests: vocabulary, digit symbol,

letternumber sequencing, CVLT total learning and

CVLT short delay recall. Adjusting for age and gender,

differences in vocabulary and digit symbol remained

statistically significant, whereas differences in digit span

forward, letternumber sequencing, TMT part A and

CVLT total learning were bordering on being significant

(P17 years 8 13.8 58 14.2

1517 years 20 34.5 104 25.5

17 years or never 9 15.5 129 31.6

1517 years 26 44.8 207 50.7


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gender was related to poorer performance on CVLT total

learning.

Vocabulary and digit symbol performance:

SUD characteristics

Restricting analyses to the SUD group (n = 58), we

assessed the effects of diagnosis type (abuse versus depen-

dence), current disorder (current versus in remission),

early onset of SUD (age at SUD onset: 18 years versus

19 years), number of life-time SUD diagnoses (1 versus

at least 2) and comorbid Axis I disorder, and personality

disorder on vocabulary and digit symbol performance. In

vocabulary, participants with a substance abuse diagno-sis performed poorer than those with a substance depen-

dence diagnosis (38.8 versus 45.0, t= -2.49, df= 56,

P


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Table

5

Multipleregressionmodelsofcog

nitivemeasures(standardizedvariables)on

substanceusedisorder(SUD)diagnosisandriskfactors,adjustingforageandgender.

Variable

Voc

abulary

Digitsymbol

Digitspanforward

Letter-num

ber

TMT:partAa

CVLT:totalb

b

(95%CI)

b

(95%CI)

b

(95%CI)

b

(95%CI)

b

(95%CI)

b

(95%CI)

Age

0.0

4**

(0.0

1;0.0

6)

0.0

0

(-0.0

3;0

.03)

0.0

0

(-0.0

2;0.0

3)

0.0

0

(-0.0

3;0.0

3)

0.0

0

(-0.0

3;0.0

3)

0.0

0

(-0.0

3;0.0

3)

Gender:male(a)

-0.2

3*

(-0.4

1;-

0.0

4)

-0.57***

(-0.7

6;-

0.37)

0.1

8

(-0.0

3;0.3

9)

-0.0

3

(-0.27;0.2

0)

-0.0

8

(-0.3

0;0.1

5)-

0.5

2***

(-0.7

3;-

0.3

1)

Anysubstanceabuse/dependence

0.0

0

(-0.2

9;0.2

9)

-0.3

4*

(-0.6

4;-

0.0

4)

-0.1

0

(-0.47;0.2

8)

-0.2

1

(-0.57;0.1

5)

0.2

9

(-0.1

6;0.7

4)-

0.1

1

(-0.4

5;0.2

2)

Attentionorbehaviourproblems

atschool

0.0

3

(-0.3

3;0.3

9)

0.1

5

(-0.1

8;0

.48)

0.1

5

(-0.2

1;0.5

0)

0.3

2

(-0.1

0;0.7

5)

-0.1

5

(-0.6

0;0.3

0)-

0.0

2

(-0.4

1;0.37)

Aggression(b)

Moderate

0.1

1

(-0.1

4;0.3

6)

-0.0

2

(-0.2

5;0

.22)

0.3

6*

(0.0

8;0.6

3)

0.3

5*

(0.0

5;0.6

5)

-0.1

6

(-0.4

5;0.1

4)

0.0

8

(-0.17;0.3

3)

High

0.07

(-0.2

4;0.3

8)

0.1

8

(-0.1

1;0

.46)

0.0

6

(-0.2

9;0.4

1)

0.3

0

(-0.07;0.67)

-0.2

0

(-0.5

2;0.1

3)

0.1

1

(-0.1

8;0.3

9)

Parentalalcoholproblems

0.0

4

(-0.2

1;0.2

9)

-0.2

2

(-0.4

8;0

.04)

0.0

9

(-0.1

6;0.3

3)

-0.2

0

(-0.5

1;0.1

1)

0.2

5

(-0.0

3;0.5

3)

0.0

5

(-0.2

0;0.3

0)

Parentalbasiceducation(c)

-0.3

3**

(-0.57;-

0.0

9)

-0.4

8***

(-0.7

4;-

0.2

2)

-0.1

5

(-0.37;0.0

8)

-0.3

8**

(-0.6

1;-

0.1

4)

0.17

(-0.1

0;0.4

4)-

0.2

1

(-0.4

9;0.0

6)

Ageatinitiationofdailysmoking(d)

>17years

-0.0

6

(-0.3

2;0.1

9)

-0.2

1

(-0.5

0;0

.07)

-0.2

2

(-0.5

2;0.0

9)

0.1

4

(-0.2

1;0.4

9)

0.2

0

(-0.1

1;0.5

1)

0.2

8

(-0.0

4;0.6

1)

1517years

-0.2

0

(-0.47;0.0

8)

-0.1

3

(-0.4

0;0

.15)

-0.2

5

(-0.5

4;0.0

5)

0.0

0

(-0.2

9;0.2

8)

0.1

1

(-0.1

8;0.4

0)

0.0

5

(-0.2

0;0.3

1)

Study - Substance consuption

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