Relationship between positive and negative symptoms and neuropsychological scores in frontotemporal dementia and Alzheimer's disease

Patients with dementia, particularly those with frontotemporal dementia (FTD), are reported to display marked negative symptoms, including apathy, lack of initiative, and flattened affect, similar to those observed in schizophrenic patients. However, negative symptoms have yet to be formally quantified in an FTD population. Twenty-seven patients with FTD (11 primarily right-sided, 8 primarily left-sided, and 4 symmetric) and 7 patients with Alzheimer's disease were rated on the Scale for the Assessment of Negative Symptoms, the Positive and Negative Syndrome Scale, and the Emotional Blunting scale. The FTD patients registered significantly more negative symptoms than the Alzheimer's patients, averaging a threefold increase; groups did not significantly differ in positive symptoms. Negative symptom scale scores were negatively correlated with nonverbal executive skills (23-44% shared variance), verbal executive skills (up to 25% shared variance) and verbal memory (up to 20% shared variance), but were unrelated to measures of attention, verbal and nonverbal information processing, nonverbal memory, language, and constructional skill. In contrast, positive symptoms were positively correlated with constructional skill (19% shared variance) and attentional scores (15% shared variance). These findings add to the existing literature relating negative symptoms to anterior cerebral hypofunction, and suggest that positive symptoms, at least in this population, may be tied to increased posterior activation.