Personality Changes May Help Distinguish Between Types of Dementia

ST. LOUIS, May 31 -- The appearance of passive personality traits in an older adult with signs of dementia may signal the presence of Lewy bodies rather than Alzheimer's disease, said investigators here.

Among 290 older adults in a longitudinal study, specific personality traits involving social withdrawal and purposeless hyperactivity helped distinguish between the two types of dementia, wrote James E. Galvin, M.D., M.P.H., of the Alzheimer Disease Research Center at Washington University School of Medicine, and colleagues.

"Our results suggest that incorporating a brief, simple inventory of personality traits may improve the identification of individuals with dementia with Lewy bodies," reported the investigators in the May 29 issue of Neurology.

Early identification of dementia helps patients and families plan for the inevitable decline in cognitive function, the authors noted.

"Much effort has focused on the cognitive symptoms of dementia syndromes, such as impairments in memory, visuospatial, attention, and executive function," they wrote. "An alternative approach to improve early detection is to study noncognitive symptoms such as behavioral and personality changes that may precede diagnosis or occur early in the course of the dementia."

The mean age of the study patients was 77.6 + 9.9 years, and the sample included 128 patients with dementia with Lewy bodies, 128 patients with Alzheimer's disease, and 34 controls who did not have dementia.

In annual interviews with a collateral source, such as a spouse or caregiver, the investigators asked whether the patients had specific changes in their personalities, interests, and drives, based on items from the Blessed Dementia Scale.

The primary outcome measure was a change from no dementia to dementia, with risk factors calculated using chi-square and Fischer exact tests. The authors also performed factor analysis to determine underlying structure and receiver operating characteristic curves assessing the ability for each of three derived factors to discriminate Lewy body dementia from Alzheimer's.

Over a mean of 4.8 visits (range one to 14), the authors identified four personality traits that could distinguish dementia with Lewy bodies from Alzheimer's. These were:

• Diminished emotional responsiveness (P=0.004)
• Relinquishing hobbies (P=0.01)
• Growing apathy (P=0.03)
• Purposeless hyperactivity (P=0.003)

On factor analyses of the Blessed Dementia Scale items, the authors found that the four factors above, rated as passive symptoms, explained 10.4% of variance, and were significantly more likely to be seen among patients with dementia with Lewy bodies than among those with Alzheimer's disease (P=0.001).

In addition, the researchers said, any personality change was associated with the occurrence of visual hallucinations.

Taken together, the four passive factors successfully discriminated one type of dementia from the other, as measured by an area under the curve of 0.61 (95% CI, 0.54 to 0.68, P=0.006).

"We also found that, compared with non-demented older adults, there is a general dementia phenotype of increased rigidity, increased egocentricity, loss of concern for the feelings of others, coarsening of affect, and impaired emotional control," the authors wrote.

"These findings are consistent with other studies reporting personality changes in Alzheimer's disease," they said. "In the absence of autopsy confirmation, however, it is impossible to know how many individuals in these prior studies of Alzheimer's disease personality traits had concurrent Lewy bodies."

The authors noted that the study was limited by the "coarse and non-quantifiable" ratings on the Blessed Dementia scale, and the lack of information from informants about the degree of change in an individual patient.

In addition, they acknowledged, the sample was not population based and participation was voluntary, which could introduce selection bias.