A meta-analytic review of verbal fluency deficits in Huntington's disease

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurology

Background:

• Huntington's disease (HD) is a progressive neurodegenerative disorder.
• Cognitive deficits, particularly in executive functions, are common in HD.
• Fluency tests (phonemic and semantic) are often used to assess executive functions.

Purpose of the Study:

• To compare the magnitude of phonemic and semantic fluency deficits in Huntington's disease patients versus healthy controls.
• To determine if fluency deficits in HD reflect executive dysfunction or a more generalized cognitive impairment.

Main Methods:

• A meta-analysis was performed on 30 studies.
• Included 1,511 participants (Huntington's disease patients and healthy controls).
• Compared performance on phonemic and semantic fluency tests.

Main Results:

• Symptomatic HD patients exhibited comparable impairments on both phonemic and semantic fluency tests (rs=.71 and .73).
• Unlike patients with focal frontal lesions, these deficits were not differential relative to verbal intelligence or psychomotor speed.
• Fluency deficits in HD did not appear to be specific to executive functions.

Conclusions:

• Deficits in phonemic and semantic fluency in Huntington's disease patients suggest a generalized cognitive impairment.
• These findings differentiate HD from conditions with focal frontal cortical lesions where executive dysfunction is prominent.
• The results indicate that fluency impairments in HD are not solely indicative of executive dysfunction.