[Does hearing loss in adults diminish intelligence?].

Background And Objective: Mean curves of the age course of intelligence drop shortly after early adulthood. This is particularly true of fluid intelligence, which corresponds to the immediate management of information. Less affected is crystallized intelligence, i.e. acquired knowledge. Overviews indicate that visual impairment such as cataracts explain a large portion of this intelligence loss, and that the restitution of visual capacity conspicuously increases fluid intelligence. The question also arises as to whether hearing loss acquired in adulthood can cause a similar loss in mental efficiency.

Methods: This question was investigated by reviewing the relevant literature.

Results: Several studies were found involving aspects of the relationship between acquired hearing loss and the impairment of intelligence. In general, the expected association was confirmed.

Conclusions: By and large,we can expect acquired hearing loss to lead to an impairment of fluid intelligence. In the long-term, such a loss can also reduce the crystallized intelligence. Such decreases are disadvantageous in many areas of an information based society.