Updated

Bipolar disorder, a brain disorder that strikes early and can cause lifelong disability, is chronically undertreated in many low-income countries, government researchers reported.

Their survey of more than 61,000 patients suggests 2.4 percent of the world's population may have some form of the disease, which is marked by bizarre shifts in mood, energy and activity that can affect relationships and job performance.

"Bipolar disorder is responsible for the loss of more disability-adjusted life-years than all forms of cancer or major neurologic conditions such as epilepsy and Alzheimer's disease, primarily because of its early onset and chronicity across the life span," Kathleen Merikangas of the National Institute of Mental Health and colleagues wrote in the Archives of General Psychiatry.

Her team conducted surveys of adults in the United States, Mexico, Brazil, Colombia, Bulgaria, Romania, China, India, Japan, Lebanon and New Zealand.

They found that less than half of those with bipolar disorder -- also known as manic-depressive illness -- received mental health treatment during their lifetimes. In low-income countries, only 25.2 percent of bipolar patients said they had any contact with the mental health system.

Three-quarters of those with bipolar disorder also met the diagnostic criteria for at least one other disorder, with anxiety disorders being the most common shared illness, the team found.

More than half of people said their symptoms started in adolescence, underscoring the need for early detection and treatment, the researchers said.

"In light of the disability associated with bipolar disorder, the lack of mental health treatment among those with bipolar disorder, particularly in low income countries, is alarming," the team wrote.