Tannock,
R. (2013). Specific learning disabilities in
DSM-5; Are the changes for better or worse. The
International Journal for Research in Learning Disabilities, 1(2),
2-30.
Prof.
Rosemary Tannock was a
member of the DSM-5 Work-Group for ADHD and Disruptive Behavior Disorders and a
Liaison member of the Neurodevelopmental Disorders Work Group to advise on
Learning Disabilities.
In this
paper she describes the considerations that lead to the decisions that were made regarding LD diagnostic criteria. I'll
present her views in black or orange, and thoughts of mine in green.
This post
does not "cover" all the aspects the paper discusses, but rather
focuses on the things that were interesting to me. Because of the post's length, it's divided
into two parts. This is part A.
"DSM-5, the fifth edition of the
American Psychiatric Association’s Diagnostic
and Statistical Manual of Mental Disorders, was published in May 2013, amidst
a storm of controversy. As with the
previous versions, this new volume has received strong criticism from the
public, individuals with LD and their families, policy makers and well as from
clinicians and researchers in the field of mental health.
One of the ongoing concerns was that this
version of the DSM continues to reify the concept of ‘discrete disorders’ of
the mind, based on various sets of observable signs and symptoms, rather than
on specific biological tests or atypical patterns of brain-based states. However, since scientific knowledge had not
yet advanced enough to use neuroscience and genetics to shape the
conceptualization of mental disorders in DSM-5, the diagnostic criteria were to
remain as behavioral descriptors.
The DSM has a broad influence not only on
the diagnosis of mental disorders, but also on how they are perceived by the
public, healthcare personnel, employers, and those in the school and judicial
systems; how they are funded by medical insurance agencies; how the public
policy for mental health is maintained or changed; and how research agendas are
set.
Significant
changes in diagnostic criteria undermine our ability to rely on research done thus
far. All previous learning disabilities
(LD) research was done in light of the old criteria. Research subjects were divided into LD groups
and control groups according to the old criteria, thus conclusions about
differences between LD and non – LD persons are valid for people diagnosed in
light of the old criteria.
LD is a "disorder" in DSM5,
since medical conditions are called disorders rather than disabilities:
‘Learning Disabilities’ is an educational term.
I still wonder why LD
should appear in the DSM and why it is considered to be a "medical
condition".
The DSM-5 Manual advises that the
diagnostic criteria “are offered as guidelines for making diagnoses, and their
use should be informed by clinical judgment.”
The
field lacks a complete understanding of LD: instead there are burgeoning
descriptions, guises, guesses, hypotheses, and controversies. To date, there is
no international consensus as to what constitutes LD, its operational
definition (diagnostic criteria), or who can or cannot conduct the required
assessment or make the diagnosis.
Early perspectives of LD, in the 1960's,
recognized that impaired academic skills (reading, arithmetic) occur in the
context of average or even superior intellectual abilities. Other important
insights from these early perspectives include the notion that LD (dyslexia)
was congenital, heritable, and manifested primarily by males. Underlying cognitive deficits
(possible causal factors) focused initially on visual problems. For
example, Hinshelwood (1917) postulated that the primary disability of children
with word blindness was in visual memory for letters and words and that it was
an inherited condition.
According to the U.S. Federal Law (IDEA,
2004, 20 USC Sec. 1401 (30, SLD), LD is defined as “a disorder in one or more basic psychological
processes involved in understanding or using language, spoken or written, that may manifest
itself in the imperfect ability to listen, think, speak, read, write, spell, or
d arithmetical calculations.” Thus the notion of underlying
deficits in cognitive processing as causal factors was instantiated in the conceptualization
of LD. CHC
abilities are of course cognitive abilities and thus a disability in one or
more CHC abilities is one of the criteria for LD diagnosis not only according
to Flanagan but according to the US federal law as well.
This prevailing legal definition
restricts the concept of LD to a language-based disorder, but does not include
non-language-based learning difficulties, such as dyscalculia, as defined by
some researchers. Motor skills are also not included. It does seem like
language gets in this definition a role more central than it should take. Difficulties in
thinking/reading/ writing/ arithmetic etc. can have many other causes beyond
language.
According to DSM-5, SLD (specific
learning disorder) is a type of Neurodevelopmental Disorder that impedes the
ability to learn or use specific academic skills, such as reading, writing, or
arithmetic, which serve as the foundation for other academic learning. The
learning difficulties are ‘unexpected’ in that other aspects of development
seem to follow a typical trajectory, or are only minimally delayed. Early signs
of learning difficulties may be discernible in the preschool years (e.g.,
difficulty learning names of letters or to count objects), but they can only be
diagnosed reliably after starting formal education.
In DSM-5, SLD is understood to be a
chronic condition that typically persists into adulthood, albeit with changes
in the way the learning difficulties manifest. In part, this is because adults
learn compensatory strategies (e.g., avoid reading by using other media to
obtain information or for calculation; use specialized software to assist with
reading/writing activities or calculators to assist with numerical
activities). Adults
can also use non-technical compensatory strategies like the ability to
comprehend what they read despite inaccurate decoding due to better use of
general knowledge and deduction skills.
The causes of SLD are unknown, but
research suggests the learning difficulties run in families, are heritable, and
involve interplay of both genetic anomalies and environmental factors (e.g.,
prematurity, prenatal exposure to neurotoxins from tobacco, alcohol, street
drugs, or other environmental toxins). Neither are the underlying mechanisms of
SLD known, although both neural and psychological accounts exist, particularly
for difficulties learning to decode words.
Neuroimaging studies have revealed alterations in both structure and
function, but it is unclear whether these brain differences are a cause,
consequence or correlate of SLD.
A
developmental history of Speech Sound Disorder and/or Specific Language
Impairment in preschool years is a common precursor of all three LD categories
listed in DSM-IV-TR (reading, writing, mathematics), but particularly for poor
skills in reading comprehension, spelling, arithmetic fact retrieval, and
calculation. Moreover, one longitudinal
study of a community-based sample of children identified with pervasive
speech/language disorders in kindergarten were found to have an estimated 3- to
6-fold greater risk for LD (all categories alone or in combination) in young
adulthood compared to typically-developing youngsters.
Longitudinal studies provide strong evidence
of a developmental accumulation of learning difficulties with increasing
cognitive demands of the curriculum. For instance, children with speech sound
disorders in early childhood, later manifest difficulties learning to read,
spell, and write in the school years.
Also, over 50% of children with phonologically-based reading
difficulties but no apparent difficulties in learning basic arithmetic at age 5
years, manifest learning difficulties in mathematics as well as continued
problems in reading at age 7. However,
intervention outcome studies provide no evidence that intervention for one
academic domain or its subskills transfer to other academic domains.
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