Elderly people with dementia or diminished mental capacity are increasingly being targeted in consumer fraud and related complaints nearly doubled in the decade through fiscal 2013, officials of the National Consumer Affairs Center reported.

The number of such complaints handled by consumer centers nationwide came to around 10,600 in the previous fiscal year, which ended in March, including instances of investment fraud and unauthorized delivery of expensive items, the officials said Saturday.

The figure almost doubled from the roughly 5,800 cases reported in fiscal 2003. By contrast, similar fraud cases involving people of any age declined to about 920,000 from 1.51 million over the same period.

In graying Japan, the population of elderly with dementia who require care increased to more than 3 million in 2012 against 1.49 million in 2002. The figure is projected to exceed 4 million in 2020, according to the government.

Even if family members discover such scams in progress, it is difficult to recover the loss because dementia often prevents patients from explaining or recalling how the contract was sealed, according to Kenji Ota, a lawyer specializing in consumer fraud cases.