Search

Background: While much disinhibition in dementia results from generalized impulsivity, in behavioral variant frontotemporal dementia (bvFTD) disinhibition may also result from impaired social cognition. Objective: To deconstruct disinhibition and its neural correlates in bvFTD vs. early-onset Alzheimer’s disease (eAD). Methods: Caregivers of 16 bvFTD and 21 matched-eAD patients completed the Frontal Systems Behavior Scale disinhibition items. The disinhibition items were further categorized into (1) “person-based” subscale which predominantly associated with violating social propriety and personal boundary and (2) “generalized-impulsivity” subscale which included nonspecific impulsive acts. Subscale scores were correlated with grey matter volumes from tensor-based morphometry on magnetic resonance images. Results: In comparison to the eAD patients, the bvFTD patients developed greater person-based disinhibition ( P < 0.001) but comparable generalized impulsivity. Severity of person-based disinhibition significantly correlated with the left anterior superior temporal sulcus (STS), and generalized-impulsivity correlated with the right orbitofrontal cortex (OFC) and the left anterior temporal lobe (aTL). Conclusions: Person-based disinhibition was predominant in bvFTD and correlated with the left STS. In both dementia, violations of social propriety and personal boundaries involved fronto-parieto-temporal network of Theory of Mind, whereas nonspecific disinhibition involved the OFC and aTL.

The clock-drawing test (CDT) is widely used in clinical practice to diagnose and distinguish patients with dementia. It remains unclear, however, whether the CDT can distinguish among the early-onset dementias. Accordingly, we examined the ability of both quantitative and qualitative CDT analyses to distinguish behavioral variant frontotemporal dementia (bvFTD) and early-onset Alzheimer disease (eAD), the 2 most common neurodegenerative dementias with onset

Investigators have reported high sensitivity and specificity values for single photon emission computerized tomography (SPECT) when distinguishing Alzheimer's disease (AD) patients from normal elderly controls or from selected patient groups. The role of SPECT in identifying AD among unselected patients with memory complaints requires investigation. We examined 139 consecutive patients with 99Tc-HMPAO SPECT. NINCDS-ADRDA diagnoses were determined blind to SPECT results, and scans were read and classified by visual inspection blind to clinical diagnoses. Bilateral temporoparietal hypoperfusion (TP) occurred in 75% of probable, 65% of possible, and 45% of unlikely AD patients, yielding a sensitivity of 75% and a specificity of 52% when comparing probable AD versus unlikely AD groups. A positive predictive value of 78% was obtained based on a 69% prevalence of AD in our total clinic population. Patients with false-positive results included a variety of dementing illnesses; all patients with bilateral hypoperfusion had dementia. A pattern of TP on SPECT scans is seen in most patients with AD, but could be found in other dementias as well and cannot be regarded as specific to AD. Reduced TP perfusion discriminated between demented and nondemented individuals. Further strategies for SPECT interpretation that improve diagnostic specificity should be sought.

New-onset epileptic seizures occur in patients with Alzheimer's disease (AD), but the nature and underlying reasons for these seizures are unclear. We identified new-onset, nonsymptomatic seizures in 77 (17%) of 446 patients with uncomplicated, definite AD on autopsy. Among these seizure patients, 69 had generalized tonic-clonic seizures, and 55 had less than three total seizures. The seizure patients had a younger age of dementia onset than did the remaining AD patients; however, at seizure onset, they averaged 6.8 years into their AD and had advanced dementia. When further compared to 77 AD controls, matched for age of onset and duration, the seizure patients did not differ on medical illnesses, amount of medications, and degree of focal neuropathology. We conclude that a few unprovoked generalized seizures frequently occur late in the course of AD, and that AD patients with a younger age of dementia onset are particularly susceptible to seizures.

This study investigated the cognitive estimations test (CET) in patients with frontotemporal dementia (FTD) and Alzheimer's disease (AD). The CET consists of questions which reflect judgment and reasoning. FTD patients, who have predominant frontotemporal atrophy, may give more extreme estimates on the CET compared to AD patients, who have greater temporoparietal pathology. The CET was administered to 31 FTD and 31 AD patients of comparable dementia severity plus 31 normal elderly controls. Both dementia groups gave significantly more extreme estimates on the CET than did the controls, and, contrary to expectations, AD patients gave more extreme estimates than did FTD patients. Extreme CET scores correlated with poor savings and calculations scores on neuropsychological tests. In conclusion, the CET may be particularly impaired in AD because it reflects impaired memory and numerical ability as well as disturbed judgment and reasoning. The CET may also be helpful in discriminating some patients in moderate stages of AD from those with FTD.

Frontotemporal dementia (FTD) is a common neurodegenerative dementia syndrome. Compulsive behaviors frequently occur in FTD and may be presenting symptoms of this disorder. This study evaluated compulsive behaviors as presenting symptoms in 29 patients with FTD compared to 48 patients with Alzheimer's disease (AD) enrolled in the UCLA Alzheimer's Disease Center. The FTD patients met the Lund and Manchester criteria for FTD and had predominant frontal hypoperfusion on single-photon emission computer tomography neuroimaging. The AD patients met National Institute of Neurological and Communicative Disorders-Alzheimer's Disease and Related Disorders criteria for clinically probable AD. Compulsive behaviors occurred in 11 FTD patients (38%) versus 5 AD patients (10%) (χ2 = 6.73, P < .01). This difference persisted after controlling for the younger age of the FTD group. There was a range of compulsive behaviors, with the most frequent being repetitive checking activities. Compulsive behaviors are common presenting symptoms among FTD patients and may result from an inability to inhibit urges to perform compulsive movements from damage to frontal-striatal circuits.

In the absence of pathognomonic clinical features, the clinical diagnosis of Alzheimer's disease (AD) remains one of exclusion of other dementias. We investigated the clinical diagnoses among 394 neuropathologically confirmed AD cases in a dementia brain bank. Most patients were correctly diagnosed as AD (348 or 88%). Among the misdiagnosed patients, AD was mistaken for a primary depressive disorder in 14, multi-infarct dementia in 13, Parkinson's disease in nine, and alcoholic dementia in four. The number of misdiagnosed AD patients did not differ between physician specialties but was greater among AD patients with agitation, depression, paranoia, or delusions. This retrospective study suggests that the diagnostic sensitivity for AD is high among a cross-section of practicing physicians and that an important factor in mistaking AD for another illness is unfamiliarity with the potential psychiatric symptoms of AD. ( J Geriatr Psychiatry Neurol 1991;4:26-29).