In dopamine the key to predicting the disease two years earlier
di Paola Raschielli
21 May 2021 - A study conducted by IRCCS Santa Lucia of Rome, Università Campus Bio-Medico di Roma and University of Turin, recently published on Journal of Alzheimer's Disease, checked the link between Alzheimer's and dopaminergic circuit impairments in patients with mild cognitive impairment, an important risk factor for the development of the disease and other forms of dementia. The team composed by Dr. Laura Serra, by prof. Marcello D'Amelio and by prof. Marco Bozzali demonstrated that the reduction of the connections of the ventral tegmental area (VTA) to other areas of the brain anticipates brain damage and the appearance of the first clinical symptoms by about two years. A window of time within which drugs can be used e therefore counteract the evolution of the disease in advance. The clinical study is the result of translational research that began in 2017, when the group coordinated by Prof. D'Amelio, Professor of Human Physiology at Ucbm, identified in the VTA, linked to the production of dopamine, one of the first events in the course of disease development through a pre-clinical trial. "In this study we focused on the connections that are established between the VTA and the rest of the brain - explains D'Amelio - and how these, due to damage to the VTA, change in the course of the disease. The result was the surprising ability that lesions of the VTA have in predicting the development of Alzheimer's disease."
Through the use of functional neuroimaging and neuropsychological tests, two painless and non-invasive techniques, the activity of the VTA was analyzed in 35 patients with mild cognitive impairment and the evolution of the patients' condition was monitored for 24 months. In 16 of the 35 patients the mild cognitive impairment converted to Alzheimer's disease and this conversion was anticipated by a significant reduction in VTA connectivity to brain areas critical for disease symptoms. In patients who did not develop the disease, however, the VTA maintained its function unchanged.
The study also confirmed the greater specificity of this method in diagnosing the disease. In fact, patients with atrophy of the hippocampus, an area of the brain responsible for memory, but without a reduction in VTA activity, did not develop Alzheimer's disease, confirming previous studies that found the synergistic presence of brain atrophy and VTA disconnection events related to the early presentation of clinical symptoms of the disease.
