Alzheimer’s disease (AD) patients. 3 The pattern and degree of focal atrophy was investigated in 17 patients with nonfluent PPA, 11 FTD patients, and 24 probable AD patients, using a computer-automated volumetry and compared to cognitive impairment (T. Fukui and A. Kertesz, presentation at conference). Regional total brain volume ratios showed that the right frontal lobe was significantly smaller in patients with FTD ( p 0.001) and that the biparietal ratios tended to be smaller in patients with AD. When the frontotemporo-central regions were combined to represent the anterior brain, the left anterior brain ratio was significantly smaller in patients with PPA ( p 0.01). Generally, verbal functions represented by the Western Aphasia Battery, the Dementia Rating Scale (DRS), or verbal IQ for the Wechsler Adult Intelligence Scale Revised correlated mainly with left frontal, temporal, and central regional volume; the performance IQ was associated with bilateral frontotemporal and right parietal volume. These results support a view that the behavioral presentation of FTD is associated with right frontal atrophy and that left-sided perisylvian atrophy is a feature of PPA. 5 Volumetric measurements were compatible with the actual clinical diagnoses in more than 70% of the patients. Functional Imaging A positron emission tomography study was conducted to address the question of a specific organization for behavioral and affective behaviors in the frontal lobes (M. Sarazin et al, conference paper). A previous study of brain activity at rest had shown a double dissociation between cognitive performance and behavioral scores in patients with frontal lobe lesions. 6 Performance in executive tasks was correlated only with the regional glucose metabolism of the dorsolateral prefrontal cortex, whereas behavioral disturbances scored by a family informant were specifically associated with the orbitofrontal cortex. In this study, a total of 27 patients, or 15 with the behavioral presentation of FTD and 12 with focal frontal lobe lesions (4 right, 5 left, and 3 bilateral), were included. Behavioral disturbances were evaluated by administering the Lhermitte and colleagues’ scale 7 to the patient informants; the scale consists of 80 questions regarding 16 behavioral items. When 18 F-fluorodeoxyglucose high-resolution positron emission tomography was performed at rest, significant negative correlations were found between glucose metabolism in the orbitofrontal cortex and Brodmann’s area 10 bilaterally, and behavioral deficits such as apathy (with a correlation coefficient that reaches 0.93 in right medial area 10), stereotypy, euphoria, disinterestedness, dependence on the social and physical environment, indifference to rules, attention and programming deficits, and loss of intellectual control. Metabolic values in amygdala highly correlated with impulsiveness, personality disturbances, and loss of emotional control. The right frontal lobe was more implicated than the left one in behavioral and emotional control. Social and mental disinhibition, corresponding to stereotypy, indifference to rules, and loss of intellectual control, were strongly associated with hypometabolism in right orbitofrontal cortex. Impaired affective and emotional control, corresponding to impulsivity, personality changes, and loss of emotional control (including irritability, increased anger, and fre