This finding suggests that increasing age might be a major risk factor in FTD, as in other major neurodegenerative disorders such as AD and PD. It should be pointed out, however, that most Salvianolic-acid-B previous studies have used age at onset rather than age at diagnosis which was used in this study. Although the use of age at onset avoids problems of patient and doctor delay, the estimation of time from onset to diagnosis is notoriously difficult and might be subject to very different interpretation from case to case. Only cases diagnosed with FTD in each respective year are registered in SveDem, thus avoiding the risk of inclusion of patients with a previous diagnosis of FTD. While it is well documented that AD affects more women than men, and the reverse is true for DLB/PDD, there is conflicting data on the gender ratio in FTD. There was only a slight preponderance of women than men that received a diagnosis of FTD in the present study, supporting a more equal sex distribution in FTD than in AD, PDD or DLB. While data from SveDem reflects the distribution in the general population, previous discrepancies in gender ratio might reflect differences in recruitment strategy and the population studied. The presence of a first-Eleutheroside-E degree relative with dementia is common in both AD and FTD, suggesting that genetic risk factors are important in both these disorders. In FTD, several genetic mutations have been described that can lead to autosomal dominant hereditary disease. Previous estimates of the proportion of familial FTD has varied between 10�C40% of cases, although the high community prevalence of other types of dementia in the elderly might make estimates of the proportion of familial cases uncertain. The results of the present study confirm a high degree of positive family history in first-degree relatives of cases with AD and FTD. Cases with second-degree relatives were uncommon and autosomal dominant mutations have more recently been estimated to account for only around 10% of cases with AD and FTD. Data from SveDem also suggests that the proportion of cases with a positive family history is similar in FTD and AD. The presence of a positive family history in FTD might, however, have been underestimated, especially in second-degree relatives. The questions used in SveDem do not specifically address the symptoms specific for FTD, and a significant proportion of responses were either ����Not known���� or data was missing. On the other hand, previous estimates of a high prevalence of positive family history in FTD might have been influenced by referral bias and research interest in familial cases as well as the high prevalence of dementia in the general population. Another possible explanation for the lower proportion of familial FTD cases in SveDem could be that the available data does not differentiate between cases with bvFTD and the primary progressive aphasias. Autosomal dominant mutations and a positive family history are more common in bvFTD than in either SD or PNFA. The main limitation of the present study is that the clinical data leading to diagnosis is not available. Consequently, it is not possible to control the validity of the diagnosis in each individual case. Furthermore, neuropathological confirmation of the diagnoses was not available.