Abstract
Crystallized intelligence refers to one's knowledge base and can be measured by vocabulary tests. Fluid intelligence is related to nonverbal aspects of intelligence, depends very little on previously acquired knowledge, and can be measured by tests such as Block Design (BD) and Raven Colored Matrices (RCM). Premorbid intelligence quotient (IQ) refers to one's intellectual ability level previous to the onset of disorders like mild cognitive impairment (MCI) and Alzheimer's disease (AD) and it is important to estimate disease severity. The objective was to compare performance in tests that measure crystallized and fluid intelligence in healthy subjects and patients with amnestic MCI (aMCI) and AD. One hundred forty-four participants (aMCI (n = 38), AD (n = 45), and healthy controls (n = 61)) were submitted to neuropsychological tests (WAIS-III vocabulary, BD, and RCM). There were significant among groups, except for vocabulary, indicating a relative stability of crystallized intelligence in the continuum from normal to pathological cognitive decline. Vocabulary seems to be stable during the progression of the disease and useful as a measure of premorbid intelligence, that is, to estimate previous function in relation to the level of education and, as a collateral measure of cognition in people with low education.
Highlights
In the early 1940s, two types of intelligence were distinguished [1]
The sample consisted of 144 older adults who were classified into three levels of cognitive performance: normal controls (NC) (n = 61), patients diagnosed as having amnestic mild cognitive impairment (n = 38), or patients diagnosed as having Alzheimer’s disease (AD) (n = 45)
Vocabulary, Block Design (BD), and Raven Colored Matrices (RCM) were associated with Mini-Mental State Examination (MMSE) scores among NC and amnestic MCI (aMCI) participants, but not among AD patients
Summary
In the early 1940s, two types of intelligence were distinguished [1]. One type of intelligence was described to have a physiological substrate, to reach its peak in early adulthood, and to decline linearly with age. A bifactorial model of intelligence described the former type as fluid and the latter as crystallized intelligence [2] This model proved to be quite influential in the field of Gerontology as longitudinal studies confirmed their differential paths of change in adulthood [3]. Crystallized intelligence is associated with an individual’s knowledge base, such as knowing the vocabulary and rules of the language and historical facts. It encompasses skills required in the navigation of everyday situations and it is usually associated with the notion of “social intelligence” or “common sense” [4]. Previous studies have repeatedly shown that crystallized intelligence remains stable in adulthood [3]
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