ADHD and Seasonal Affective Disorder

ADHD and Seasonal Affective Disorder (SAD): Are they Linked?

Is it possible that ADHD is a seasonally fluctuating disorder? It sounds intriguing, but remember, for diagnostic purposes, classic ADHD symptoms such as hyperactivity, impulsiveness and inattentive behaviors (beyond the normal range of age-appropriate behavior) must persist for a set period of time (the typical cutoff is 6 months for most cases). Nevertheless, it is worth investigating whether there is any sort of seasonal pattern to the disorder. If there is, there could be far-reaching implications such as medication dosages (if diagnosed or initially treated during a "high ADHD symptom" period may result in effects of over-medication for the rest of the year, while initial dosing during a "low-tide" season of ADHD symptoms may prove inadequate in the later months).

Intuitively, we would probably assume that ADHD symptoms would be worst during the dark winter months, but is there any data to support this hypothesis? As it turns out, there may be. Here are the results of a few relevant studies on the apparent connection between ADHD and seasonal related psychological disorders:

• Seasonal Affective Disorder (SAD) symptoms overlap and co-exist at higher rates in those with ADHD: A study by Levitan and coworkers on seasonal affective symptoms in adults with ADHD found that the prevalence of seasonal affective disorders was higher in the ADHD population than in the general population. This study accounted for some of the obvious factors such as geography (someone in Seattle would be more prone to seasonal related disorders than, say, someone in San Diego).
  
  Perhaps not surprisingly, the rate of appearance of seasonal affective symptoms was higher in women with ADHD (in general, depressive-like disorders such as SAD are more common in women in general). However, other interesting comparisons were seen, such as the prevalence of seasonal affective symptoms in the inattentive subtype of ADHD (as opposed to the hyperactive/impulsive or "combined" subtypes of the disorder). While this subtype connection may be interesting, it is important to remember that comorbid depression is often seen more in the inattentive-dominant forms of ADHD than the hyperactive-impulsive forms of the disorder.
  
  
• Overlap in medication treatments for ADHD and SAD: While we should be careful not to simply lump a bunch of disorders together just because they share similar treatment methods, the relationship between SAD, ADHD and medications such as buproprion (Wellbutrin) may be worth noting. Bupropion has shown to be clinically effective in the treatment of a whole spectrum of disorders including seasonal affective disorders.
  
  Additionally, this medication has shown its far-ranging capabilities, due, in part to its success as both an anti-depressant and "pseudo-stimulant" (of course there is a heated debate among professionals as far as whether "Wellbutrin" should even be mentioned in the same sentence as "stimulant", but its unusual, and relatively unknown mode of action keep it from an exclusive anti-depressant label, at least in the classical sense).
  
  The reason I personally use the term "pseudo-stimulant" is that bupropion can function as a dopamine reuptake inhibitor (which is one of the major modes of action of several ADHD stimulant medications and is typically uncharacteristic of most anti-depressants which often predominantly target the brain chemical serotonin). This may be evidenced by bupropion's relative effectiveness in treating ADHD (please note that bupropion or Wellbutrin is still extensively used in ADHD treatment in place of a stimulant if there is some type of depressive related disorder, however, findings such as the one in this previous study seem to indicated that buproprion may be effective for treating free-standing ADHD without comorbid depression).
  
  While again, I should reiterate that similar treatment methods does not necessarily equate to similar disorders or conditions, the relative effectiveness of this medication for treating both disorders at least leaves the door open for the possibility that there exist similar underlying modes of action between ADHD and SAD.
  
  
• The connection between ADHD and circadian rhythms: While SAD, by definition is a seasonal (as opposed to daily) issue of cyclical patterns of time, it is worth mentioning that new research is being done with regards to differences in the chronological patterns in the bodies of individuals with ADHD. In other words, there may be an actual scientific explanation behind the reasons why your ADHD child likes to stay up until three in the morning on a consistent basis.
  
  There also appears to be an affiliation with daily rhythms and ADHD subtype. For example, while impulsivity is often more associated as a "morning" behavior, the inattentive subcomponent of ADHD appears to be more affiliated with the evening. This may factor into the differences in sleep patterns and prevalence of sleep disorders in ADHD children, and may even highlight the daily schedule differences between the ADHD subtypes.
  
  If the hypothesis that individuals with ADHD are at least partially predisposed to different patterns of circadian rhythms compared to the general population, it may stand to reason that these same individuals may also be more susceptible to seasonal fluctuations. Some studies confirm this possible "double" association of ADHD to both seasonal fluctuations and circadian rhythms.
  
  
• Overlapping treatment strategy of Light Therapy for ADHD and SAD?: There has been a recent surge of evidence that light therapy, when administered at the correct wavelengths, is an effective treatment for seasonal affective disorder (and often with measurable levels of success), may now be useful for treatment in the ADHD population.
  
  As an interesting aside, there may be some unusual side effects of ADHD stimulant medications with regards to light therapy. A case study of a single child noted that there may be a possible connection between methylphenidate and photophobia (photophobia referring to fear of or excessive sensitivity to the light). Of course this observation was limited to just one patient, but the correlation of the symptoms with methylphenidate treatment at least suggests the possibility that this is a possible (albeit) rare side effect of one of the most popular stimulant medications for ADHD currently on the market.
  
  Blogger's side note: it is also worth mentioning that this case report was also published by the same individual who brought us the interesting case study which became the topic of an earlier post in this blog: excessive talking as a potential side effect of methylphenidate treatment. I will refrain from making any comments or conclusions about this, but on a personal note, I actually enjoy reading about some of these unique side effect case studies of the popular drug, and wonder if this will result in an increased level of vigilance with regards to monitoring odd side effects of common ADHD stimulant medications in both clinical studies and individual prescriptions.
  
  
• Omega 3 (n-3) fatty acid deficiency: A common underlying factor for both ADHD and seasonal affective disorders? I saved what is perhaps the best explanation for last. It consistently has been shown that individuals with ADHD are often deficient in omega-3 fatty acids. We have even discussed the theory behind omega-3 fatty acid supplementation for ADHD in earlier bloggings. Now it appears that omega-3 deficiencies may disrupt circadian rhythms as well, possibly due to an impairment in melatonin production (melatonin is a hormone which is tightly associated with the sleep-wake cycle and hence has implications on the circadian rhythm patterns in a particular individual).
  
  This may suggest that omega-3 fatty acid deficiencies may either help cause, or exacerbate the severity of both ADHD and circadian rhythm impairments. Interestingly, there is some evidence that omega-3 supplementation may be beneficial in treating seasonal affective disorders as well. In fact, diets rich in omega-3's may be an underlying reason why seasonal affective disorders are relatively uncommon in Iceland, which, due to its far-northern location, experiences exceptionally long, dark winters.
  

While I admit that the evidence for the link between ADHD and Seasonal Affective Disorders is nowhere near as strong as for other ADHD comorbid issues (such as Tourette's, anxiety, conduct disorders, and learning disabilities), I still wanted to pass on some of the information out there supporting a possible link between the two disorders. Given the close associations both between depression and seasonal affective disorders, including the argument that SAD should be labeled as a specific subtype of depression, and the high rate of comorbidity between ADHD and depressive disorders, there is certainly a possibility that the magnitude of overlap between ADHD and SAD is greater than we might imagine.