[Anticipation in bipolar disorder: A comparison between two generations].

OBJECTIVE

The genetic phenomenon of anticipation is a pattern of inheritance that includes earlier age at onset and increased severity of symptoms in succeeding generations, and is a feature of some neurodegenerative diseases. This phenomenon is suggested to occur in bipolar disorder (BP) as well.

METHOD

Anticipation in children with BP type 1 (s2) (n = 31) and their parents (s1) (n = 31) not-consecutive generations-was assessed by analyzing clinical characteristics and prognoses.

RESULTS

Age at onset of BP type 1 in s2 (mean: 19.3 +/- 4.2 years) occurred earlier than in s1 (mean: 29.5 +/- 10.2 years) (u = 345, P < 0.001). There was a direct negative correlation between the s1 and s2 cases (r = -0.554, P < 0.001). The total number of episodes in s1 (13.9 +/- 12.3) was greater than in s2 (8.7 +/- 7), which had a higher frequency of episodes (0.6 +/- 0.3 and 1.5 +/- 1.2) (u = 357, P < 0.001). There was a direct correlation between total episodes and the frequency of manic episodes between s1 and s2 (r = 0.312, P < 0.001 and r = 0.365, P < 0.001, respectively). We observed that 72.7% of BP type 1 parents that had episodes with psychotic features had offspring that had episodes with psychotic features.

CONCLUSIONS

Results of this study show that age at onset was earlier and the frequency of episodes was greater in s2 BP type 1 cases. In addition, episodes with psychotic features might be a marker for genetic anticipation.