Overactive patients may be the opposite, with unconstrained speech. Failure to respond or inappropriate responses should not be assumed to be incomprehension, but rather a concreteness of thinking or inattention. Visuo-spatial skills remain normal except for those compromised by behavioral abnormalities. Memory problems do not occur except as a result of ineffective use of memory. Thought processes show impaired powers of abstraction, verbal response and design fluency.
Comprehension is normal, however.
The length of FTD varies, with some patients declining rapidly over two to three years and others showing only minimal changes over a decade. Studies have shown persons with FTD to live with the disease an average of eight years, with a range from three years to 17 years. Serotonin-boosting medications may alleviate some behaviors. Clinical picture and differential diagnosis. Regional blood flow.