The conditions that make up affective spectrum disorder tend to occur
in multiple members of the same family in a pattern that often includes
major depressive disorder, according to an article in the February
issue of The Archives of General Psychiatry.
Other conditions within the affective spectrum include attention
deficit hyperactivity disorder, dysthymic disorder, generalized
anxiety disorder, obsessive compulsive disorder, premenstrual dysphoric
disorder, and panic disorder, as well as medical conditions such
as migraine headache and irritable bowel syndrome.
James I. Hudson, M.D. Sc.D., and his American colleagues interviewed
families to study the clustering of affective spectrum disorder
(as a whole and as individual disorders) and major depressive disorder
in individuals and families. The team hypothesized that major depressive
disorder and affective spectrum disorders are caused by common factors,
partly because the conditions within affective spectrum tend to
respond to antidepressant therapy.
The researchers interviewed 178 first-degree relatives of 64 patients
with major depressive disorder and 152 relatives of 58 patients
without the disorder. The prevalence of at least one form of spectrum
disorder among relatives of 69 patients (the 64 patients with major
depressive disorder and 5 patients who did not have that disorder)
was 39 percent (74 relatives). In contrast, prevalence was only
21 percent (29 relatives) for 53 patients who did not have any form
of spectrum disorder themselves.
The researchers found that affective spectrum disorder as a single
entity aggregated strongly within families: The likelihood for a
relative of an individual with one of those disorders having an
affective spectrum disorder themselves was 2.5 times greater than
the likelihood of such a disorder in a relative of a patient who
did not have a condition within the spectrum.
The researchers found no link between affective spectrum disorder
as a whole and alcohol use disorders or non-alcohol substance abuse
disorders.
"We found that affective spectrum disorder, viewed as a single
entity, aggregates strongly in families. We also found that major
depressive disorder displays strong coaggregation with other forms
of affective spectrum disorder, taken collectively. These findings
are consistent with the hypothesis that various forms of affective
spectrum disorder may share a heritable physiologic abnormality
critical to their origin," wrote the authors.
The authors added, "…The hypothesis would also suggest that
individuals with a family history of one form of affective spectrum
disorder would likely be at increased risk for other forms of the
spectrum as well. Recognition of this possibility might lead to
earlier diagnosis and treatment of these many conditions and may
suggest prevention strategies."