Borough Park in Brooklyn, with its preponderance of Orthodox synagogues and kosher restaurants, is the most Jewish area in the New York City region, with 78 percent of households there identifying as Jewish. Close behind is Great Neck, Long Island, with its thriving enclave of Persian Jews, and then the Five Towns, also on Long Island, where a higher percentage of Jews identify as modern Orthodox than anywhere else in the region, according to a Jewish demographic study released Tuesday.

The Jewish population in the New York area grew by 9 percent over the last decade, reversing a longstanding trend of decline, the study found. But the growth did not affect all Jewish neighborhoods equally. Two-thirds of the rise was propelled by two deeply Orthodox Jewish neighborhoods in Brooklyn with high birthrates — Williamsburg and Borough Park. Some of the city’s more affluent areas, like Brownstone Brooklyn and the Upper East Side, saw declines in their Jewish population, according to the study.

“There is no typical Jewish community,” said Dr. Pearl Beck, lead author of “The Jewish Community Study of New York: 2011,” sponsored by the UJA-Federation of New York. “We found significant differences from area to area.”

Brownstone Brooklyn, the study found, was the most secular of the region’s Jewish enclaves. In its neighborhoods, from Park Slope and Carroll Gardens to Brooklyn Heights, 43 percent of Jews identified themselves as nonreligious or secular.