Jd. Pettigrew et Sm. Miller, A STICKY INTERHEMISPHERIC SWITCH IN BIPOLAR DISORDER, Proceedings - Royal Society. Biological Sciences, 265(1411), 1998, pp. 2141-2148
Despite years of research into bipolar disorder (manic depression), it
s underlying pathophysiology remains elusive. It is widely acknowledge
d that the disorder is strongly heritable, but the genetics are comple
x with less than full concordance in monozygotic twins and at least fo
ur susceptibility loci identified. We propose that bipolar disorder is
the result of a. genetic propensity for slow interhemispheric switchi
ng mechanisms that become 'stuck' in one or the other state. Because s
low switches are also 'sticky' when compared with fast switches, the c
linical manifestations of bipolar disorder may be explained by hemisph
eric activation being 'stuck' on the left (mania) or on the right (dep
ression). Support for this 'sticky' interhemispheric switching hypothe
sis stems from our recent observation that the rate of perceptual alte
rnation in binocular rivalry is slow in euthymic subjects with bipolar
disorder (n=18, median=0.27 Hz) compared with normal controls (n=4-9,
median=0.60 Hz, p<0.0005). We have presented evidence elsewhere that
binocular rivalry is itself an interhemispheric switching phenomenon.
The rivalry alternation rate (putative interhemispheric switch rate) i
s robust in a given individual, with a test-retest correlation of more
than 0.8, making it suitable for genetic studies. The interhemispheri
c switch rate may provide a trait-dependent biological marker for bipo
lar disorder.