Friday, May 8, 2009

Methylphenidate, Anxiety and ADHD: How do they fit together?

Effects of Comorbid Anxiety on Methylphenidate Treatment in the ADHD Child:

Medication with stimulants such as methylphenidate has consistently proven to be a popular and relatively effective mode of treatment for the ADHD child. However, questions arise regarding its side effects. In particular, the effectiveness of methylphenidate (Ritalin, Concerta, Daytrana, Metadate) can be jeopardized if the child with ADHD also has some type of comorbid disorder (such as depression, obsessive compulsive behaviors, Tourette's and a host of other common associate disorders) which may be negatively impacted by the ADHD treatment. Anxiety-related disorders are seen in up to 35% of ADHD individuals, according to some studies.

Typically, treatment is met with some type of adjunctive medication to treat the comorbid disorder (which can be quite tricky, as it introduces the problem of potential drug-drug interactions, as well as a possible impairment in the effectiveness of the ADHD treatment medication), a non-stimulant method of treatment such as Strattera (atomoxetine), or non-drug alternatives (behavior therapy, EEG, nutrition and dietary strategies, etc.). While isolated behavioral therapy has limitations for treating ADHD (especially in cases of "refractory" ADHD), it has proven to be a beneficial mode of treatment for childhood anxiety disorders.

In the case of anxiety disorders alongside ADHD, treatment with stimulant medications such as methylphenidate can also be tricky. However, recent findings seem to indicate that methylphenidate is a safe mode of treatment for ADHD with comorbid anxiety. However, a new publication notes that there may be a significant distinction between the effects of anxiety on methylphenidate's effectiveness from a behavioral standpoint vs. a cognitive standpoint. Let me explain further.

When attempting to determine whether a child should be diagnosed and treated as having ADHD, the supervising physician often gives out rating forms to both parents and teachers of the child in question. Numerical rating scales with regards to classic ADHD symptoms (i.e. impulsivity, hyperactivity, inattentiveness, etc.) comprise the majority of the rating forms, and these results are tabulated and typically used in the diagnostic process. Additionally, these rating forms are often administered after a specific period of time following treatment (with medication, nutritional therapies, counseling or ADHD coaching programs, etc.) to assess the effectiveness of these treatments.

While the level of agreement between parent and teacher rating forms is generally high, significant differences may often be seen. In other words, how a child's perceived behavior in the home may be notably different than his or her behavior in the classroom. While there are an array of possible factors and explanations for this, the presence of comorbid anxiety may be an important but often overlooked reason for this discrepancy.

In the study titled: Predicting Response of ADHD Symptoms to Methylphenidate Treatment Based on Comorbid Anxiety, the researchers found that the behavioral improvements in children with ADHD were similar regardless of whether the child also had an accompanying anxiety disorder. In other words, a notable decrease in symptoms of hyperactivity, impulsiveness and behavioral annoyances was frequently seen. Since these symptoms are often more of the obvious tell-tale signs of the disorder, it would be easy to conclude (especially from a parent's standpoint) that all is well again.

However, on the opposite side of the coin, the side dealing with the cognitive deficits of ADHD (which, not surprisingly have immense academic implications), may tell a different story. The study found that for the ADHD children without an accompanying anxiety disorder, methylphenidate treatment often contributed to vast improvements in their cognitive function (and subsequent academic achievement potential). However, if the ADHD child did have an accompanying anxiety disorder, the methylphenidate treatment was significantly less effective (and possibly even counter-effective). This may serve as a possible explanation for at least some of the variability between parent and teacher evaluations of the same ADHD child.

This leads to the question: does comorbid anxiety affect the cognitive ability-enhancing effects in all academic areas or just in some of the sub-fields of academic-related cognitive functioning?

The study investigated this by administering a Weschler Intelligence Test (WISC III) to the children and examined the effects of comorbid anxiety and methylphenidate medication on three subcomponents of the test: Coding, Arithmetic and Symbol Search. An explanation of the results in these three subcategories with regards to what they measure, possible implications of these subcategories, and the effects of anxiety and methylphenidate treatment are summarized below:

  • Arithmetic: This is a timed test in which arithmetic questions are orally presented to the children and the responses are measured, assessing both speed and accuracy. Methylphenidate treatment produced a slight improvement in the ADHD children without comorbid anxiety. However, for the children with comorbid anxiety, the use of methylphenidate was ineffective (in fact, a slight decrease in performance was seen, but this was exceedingly small. It should be concluded that methylphenidate treatment had no reasonable positive effect for the ADHD children with comorbid anxiety for this particular subcategory).

    This should lead to an array of questions, including ones such as "does anxiety hamper one's performance in math, if one is ADHD (or even if one is not ADHD)?". Intuitively, we would expect the answer to be "yes", as evidenced by the huge number of children (and adults) who have self-reported "mathphobia". However, some well-reputed studies seem to indicate that methylphenidate treatment can actually help with mathematical abilities. Is there something else going on here?

    One potential explanation (not mentioned in the study) may reside in the possible presence of a third comorbid factor, such as an underlying comorbid auditory processing disorder. Auditory processing disorders are relatively common in individuals with ADHD, however, since the two disorders often exhibit symptomal overlap, comorbid auditory processing disorders are often missed in ADHD children.

    Interestingly, some recent evidence has come out that there may be a connection between auditory processing issues and anxiety disorders. This possible link between anxiety and auditory processing disorders has been addressed previously in another section of this blog. Note that the arithmetic subsection is administered orally in the WISC III test.

    If the theory that auditory processing difficulties are seen alongside anxiety disorders, it is entirely possible that the discrepancies in the ADHD with comorbid anxiety performances me be largely due to the nature of how the arithmetic portion of the test is administered. It would be interesting to see if any improvements were seen in the arithmetic scores were improved in the anxiety subgroup if the questions were presented in a written, non-auditory format.

  • Coding: This section of the WISC III test measures skills involving visual-spatial coordination, speed and concentration. The individual (for those over 8 years old) is instructed to copy a line of code substituting a number for a symbol (this would involve something along the lines of writing, say, a "1" where a star is presented, "2" for a "circle", "3" for a smiley face, etc.). A high performance in this section has implications for advanced academic tasks that involve utilizing tables and formulas (think of solving chemistry problems using data from a periodic table at the top of the page, etc.).

    In addition, a strong visual-spatial aptitude may have implications for things such as note taking skills and the like. As a result, a strength in this area may be particularly useful in upper-level courses involving the sciences, foreign languages and anything that requires an individual to "decode" and translate new information quickly. With regards to the anxiety vs. non-anxiety ADHD groups, both showed some degree of improvement with methylphenidate treatment for this subsection.

    However, the non-anxiety group showed a significantly greater positive response (around twice as big of an increase in scores for this subsection following methylphenidate treatment as the comorbid anxiety group) to the methylphenidate treatment, suggesting that comorbid anxiety was a relative impediment to methylphenidate-mediated improvements in this area as well.

  • Symbol search: This subsection involves picking out or identifying whether a particular symbol is present in a row of symbols. It has direct implications on one's ability to pay attention to detail as well as the ability to quickly scan through information to find what is relevant. Both the anxiety and non-anxiety groups showed slight improvements following methylphenidate treatment, however, once again, the improvements in post-methylphenidate scores were about twice as large for the non-anxiety group of ADHD children.

Of the 3 subtests, methylphenidate treatment helped the most in the coding section, had minimal effects in the symbol search section and little (for the non-anxiety group) to no or negative (for the anxiety group) effects for the arithmetic section.

Other studies have also investigated the effects of comorbid anxiety on cognitive task performance in ADHD children. By and large, it appears that memory-based tasks are the hardest hit by an accompanying anxiety disorder when methylphenidate is administered as an ADHD treatment. Other studies have confirmed this finding on anxiety disorders impeding memory enhancement via methylphenidate treatment. This seems to agree with the data on the coding section, which involves a type of working memory for the symbol deciphering process.

Based on what we have covered here, it would be reasonable to scrutinize significant differences between parent and teacher ratings and behavioral and attentive improvements for the possibility of an accompanying anxiety disorder to go along with an ADHD diagnosis in a child. While anti-anxiety medications can be useful, and co-administered with ADHD stimulant drugs under the watchful eye of a carefully trained physician, there is also evidence that

These findings suggest that comorbid anxiety can be a serious handicap to achieving cognitive and academic-related improvements in response to stimulants such as methylphenidate. However, please note that, based on the main study of our discussion on ADHD, anxiety and methylphenidate, notable behavioral improvements were seen from methylphenidate treatment in both the ADHD + anxiety and the ADHD minus anxiety groups.

The implications of this discrepancy can be noteworthy. To the parent who is only marginally involved with their child's academic progress, and is simply concerned with getting more manageable behavior out of their ADHD child, the sharp reduction of negative behavioral symptoms may lull the parent into a false sense of security that all is well on the home front. This stratified response to the methylphenidate medication may be lost to the unassuming parent.

However, it may be possible that an accompanying anxiety disorder (and maybe even an auditory processing disorder) may be lying there dormant to the oblivious parent. For the teacher, however, an improvement in classroom behavior due to medication, but a lack of improvement in academic work (especially in memory-related tasks) may be a tip-off that an undiagnosed accompanying anxiety disorder may be in place in this ADHD child. Thus this discrepancy in medication-derived improvements may actually serve as a potentially powerful diagnostic tool for detecting an accompanying anxiety disorder in a child being treated for ADHD.