The manic-depressive father at the center of “Infinitely Polar Bear” isn’t the only thing subject to wild mood swings. More than the usual dramatic comedy, the semi-autobiographical movie careens from the sweet to the sour. These shifts occur without warning and in a manner that’s as hard to make sense of as it must have been for writer-director Maya Forbes to comprehend when, as a child, her father was diagnosed with bipolar disorder.
The film’s title comes from a child’s malapropism for the disease, and it’s uttered by Faith, a stand-in for Forbes’s younger sister (played by Ashley Aufderheide). Imogene Wolodarsky plays Amelia, a 12-year-old version of the filmmaker. Together, these young actresses are the best things about the movie, giving it whatever sweetness it possesses.
The fun dad/scary dad act that Mark Ruffalo turns in as Cameron Stuart is appropriate, jarring and a bundle of mannerisms.
