Alzheimer's disease - neurological or psychiatric disorder?

Abstract

Alzheimer’s disease (AD), a progressive neurodegenerative disorder, is the most common form of dementia in the elderly. The clinical manifestations of Alzheimer’s disease evolve from an initial discrete impairment of recent memory to severe cognitive loss, in time behavioural and psychiatric symptoms becoming obvious and disturbing. The cause of this complex clinical picture is the gradual functional deterioration and eventually loss of all brain cell types, with severe alteration of neuronal networks supporting cognitive processes. The aim of this paper is to examine different features of AD and to formally establish whether it belongs to the neurological or psychiatric group of disorders. A review of key literature in the field was performed for main attributes of AD neuropathology and pathophysiology. In this respect, we have compared AD with classical psychiatric disorders (schizophrenia, bipolar disorder, obsessive compulsive disorder) and with neurological degenerative disorders (AD, Parkinson’s disease, epilepsy, amyotrophic lateral sclerosis, Huntington’s disease). In brief, AD pathogenic mechanisms involve protein aggregation, synapse alteration, oxidative stress, neurotransmitter deficit, intracellular calcium dyshomeostasis and mitochondrial dysfunction, all together finally leading to cell death and brain atrophy. To some extent, some of these features are common for both psychiatric and neurodegenerative disorders. However, from the cellular and molecular pathology perspective, AD seems to be closer to other neurological conditions than to classical psychiatric diseases.