Fast Five Quiz: Dementia Key Aspects

Helmi L. Lutsep, MD


May 21, 2020

The cause of frontotemporal lobe dementia is unknown, but significant evidence supports a genetic component to these syndromes. Around 40% of patients have an affected family member.

In addition to behavioral symptoms that often involve alterations in personality and social conduct, characteristics of frontotemporal lobe dementia seen during physical examination include the following:

  • Speech: Many patients have a nonfluent speech pattern, and virtually all have some degree of difficulty in naming or word finding.

  • Ideation: Ideation tends to be concrete, with poor abstraction and organization of responses and delayed shifting of cognitive sets.

  • Visual and spatial functions and constructional tasks: These are much less affected, except as influenced by behavioral and organizational difficulties. Motor skills are usually spared, except for perseverative or inattentive responses and difficulty with temporal sequencing of tasks.

  • Specific ideomotor apraxia: This is rare, except in patients with language difficulty associated with corticobasal degeneration.

  • Memory: Memory is usually preserved for orientation, although information retrieval may be difficult. Short-term memory deficits may be present in some patients but are less characteristic and more prominent in early Alzheimer disease than in early frontotemporal lobe dementia.

  • Frontal release signs: Frontal release signs, such as a positive glabellar sign, snout, grasp, and palmomental responses, may develop.

The findings in EEG are commonly abnormal in frontotemporal lobe dementia, often showing focal slowing of electrical activity over one or both frontal or temporal lobes. These findings are not sufficiently specific to be clinically useful, and, in general, EEG is less useful than functional brain imaging with PET or even lobar atrophy on MRI.

Other than brain imaging studies, the most specific tests for evaluating frontotemporal lobe dementia are evaluation with standardized language batteries and neuropsychological testing. Such studies assess the specific pattern of language abnormality and the presence of other cognitive and memory deficits. Preservation of many of these functions distinguishes frontotemporal lobe dementia and primary progressive aphasia syndromes from Alzheimer disease. The involvement of specific cognitive functions is the most important differentiating factor in distinguishing frontotemporal lobe disease from Alzheimer disease.

Read more about frontotemporal dementia.


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