There is controversy in some neurodegenerative disorders whether the presence of aberrant aggregates in a neuron could have a toxic or a protective effect. In some disorders like in encephalopathies (prion disease), protein aggregates are toxic for the neuron. In other disorders, like Huntington disease, a protective role has been suggested for the aggregates of huntingtin. In this paper, we review the role of tau aggregation and hypothesize that tau aggregates could have an insufficient protective role in damaged neurons.