Impaired initial vowel versus consonant letter-word fluency in dementia of the Alzheimer type

Early detection of Alzheimer disease (AD) is important. With AD, the loss of connectivity should first induce dysfunction in those representational networks with the weakest connectivity. Less frequently used networks have weaker connectivity. Given the letter "A" has more phonemes than the letters "F" and "S", fewer words would begin with each of these "A" phonemes than with the "F" or "S" phonemes. We wanted to learn if patients with AD would produce fewer words starting with "A".

Patients with AD, mild cognitive impairment (MCI), and normal participants, were assessed with the Controlled Oral Word Association (COWA) test.

Compared to controls and MCI patients, AD patients produced relatively fewer words beginning with "A" than with "F" and "S".

These results support the postulate that the less frequently used, and thus more weakly connected, phonetic-lexical networks are more sensitive to the degradation induced by AD.