Studies have been showing that schizophrenia is significantly associated with the risk of all-cause dementia. The neurobiological mechanisms underlying this association are not clarified, as well as, the role of antipsychotics mediating the risk of dementia.
The main aim of this work is, through the presentation of a clinical case, to show the evolution from symptoms of schizophrenia to dementia. The second aim is to present the challenges in the diagnosis and management of dementia in schizophrenic patients.
Along with the description of the clinical case we present a brief summary of a Pubmed search with the Mesh terms “schizophrenia” and “risk” and “dementia”. We selected clinical trials and review articles published in the last 5 years. From a total of 132 articles, we selected those who matched better our aims.
The patient is a 66-year-old man with a diagnosis of schizophrenia since the age of 40. In 2017 he began to develop episodes of temporal and spatial disorientation, followed by difficulties in naming and eventually functional impairment for daily activities. The initial mini mental test quoted 26/30, halving in less than two years.
The lumbar puncture revealed a Tau/Amyloid beta42 ratio compatible with Alzheimer dementia. Since language was clearly the first domain affected, it was diagnosed a logopenic variant of Alzheimer dementia.
We associated to the antipsychotic treatment galantamine 10mg and then raised it to 16mg. The loss of language was progressive, and the patient started to show psychomotor slowing and abnormal gait. We reduced paliperidone from 75mg/ml 50mg/ml but after two years of functional deterioration and apathy we eventually stopped the antipsychotic.
In the last six months the patient has been stable with galantamine 16mg, memantine 20mg, although dependent for daily activities.
Whether schizophrenia independently increases dementia incidence, or whether this correlation is confounded by traditional dementia predispositions (cerebrovascular disease, substance abuse and others) is unclear as studies have shown inconsistent results. On the other side, the cumulative use of antipsychotics for schizophrenia patients was related to cognitive decline in an observational follow-up study.
Further studies should explore whether treating schizophrenia is a potentially modifiable risk factor for dementia.