Objective-To test predictions that frontotemporal dementia and semantic dementia give rise to distinct patterns of behavioural change. Methods-An informant based semistructured behavioural interview, covering the domains of basic and social emotions, social and personal behaviour, sensory behaviour, eating and oral behaviour, repetitive behaviours, rituals, and compulsions, was administered to carers of 41 patients with semantic dementia and with apathetic (FTD-A) and disinhibited (FTD-D) forms of frontotemporal dementia. Results-Consistent with prediction, emotional changes diVerentiated FTD from semantic dementia. Whereas lack of emotional response was pervasive in FTD, it was more selective in semantic dementia, aVecting particularly the capacity to show fear. Social avoidance occurred more often in FTD and social seeking in semantic dementia. Patients with FTD showed reduced response to pain, whereas patients with semantic dementia more often showed exaggerated reactions to sensory stimuli. Gluttony and indiscriminate eating were characteristic of FTD, whereas patients with semantic dementia were more likely to exhibit food fads. Hyperorality, involving inedible objects, was unrelated to gluttony, indicating diVerent underlying mechanisms. Repetitive behaviours were common in both FTD and semantic dementia, but had a more compulsive quality in semantic dementia. Behavioural diVerences were greater between semantic dementia and FTD-A than FTD-D. A logistic regression analysis indicated that emotional and repetitive, compulsive behaviours discriminated FTD from semantic dementia with 97% accuracy. Conclusion-The findings confirm predictions regarding behavioural diVerences in frontotemporal and semantic dementia and point to diVerential roles of the frontal and temporal lobes in aVect, social functioning, eating, and compulsive behaviour. (J Neurol Neurosurg Psychiatry 2001;70:323-332)

Prospective, population-based studies that recruit participants in mid-life are valuable resources for dementia research. Follow-up in these studies is often through linkage to routinely-collected healthcare datasets. We investigated the accuracy of these datasets for dementia case ascertainment in a validation study using data from UK Biobank—an open access, population-based study of > 500,000 adults aged 40–69 years at recruitment in 2006–2010. From 17,198 UK Biobank participants recruited in Edinburgh, we identified those with ≥ 1 dementia code in their linked primary care, hospital admissions or mortality data and compared their coded diagnoses to clinical expert adjudication of their full-text medical record. We calculated the positive predictive value (PPV, the proportion of cases identified that were true positives) for all-cause dementia, Alzheimer’s disease and vascular dementia for each dataset alone and in combination, and explored algorithmic code combinations to improve PPV. Among 120 participants, PPVs for all-cause dementia were 86.8%, 87.3% and 80.0% for primary care, hospital admissions and mortality data respectively and 82.5% across all datasets. We identified three algorithms that balanced a high PPV with reasonable case ascertainment. For Alzheimer’s disease, PPVs were 74.1% for primary care, 68.2% for hospital admissions, 50.0% for mortality data and 71.4% in combination. PPV for vascular dementia was 43.8% across all sources. UK routinely-collected healthcare data can be used to identify all-cause dementia in prospective studies. PPVs for Alzheimer’s disease and vascular dementia are lower. Further research is required to explore the geographic generalisability of these findings. Electronic supplementary material The online version of this article (10.1007/s10654-019-00499-1) contains supplementary material, which is available to authorized users.

Behavioural characteristics accurately differentiate FTD from AD and CvD. The findings highlight the particular importance of affective change in FTD, and underline the role of the frontotemporal lobes in emotion.