Rare genetically defined causes of dementia.

Several genetic disorders, though rare, are associated or present with dementia. Developments in the field of genetics are contributing to clarify and expand our knowledge of the complex physiopathological mechanisms leading to neurodegeneration and cognitive decline. Disorders associated with misfolded and aggregated proteins and lipid, metal or energy metabolism are examples of the multifarious disease processes converging in the clinical features of dementia, either as its predominant feature, as in cases of Alzheimer's disease (AD) or frontotemporal dementia (FTD), or as part of a cohort of accompanying or late-developing symptoms, as in Parkinson's disease (PD) or amyotrophic lateral sclerosis with dementia (ALS-D). Awareness of these disorders, allied with recent advances in genetic, biochemical and neuroimaging techniques, may lead to early diagnosis, successful treatment and better prognosis.