Early-onset Alzheimer's disease with depression as the first symptom: a case report with literature review

Abstract

Background: Alzheimer's disease is a common neurodegenerative disease, and patients with early-onset Alzheimer's disease (onset age < 65 years) often have atypical symptoms, which are easily misdiagnosed and missed. Multimodality neuroimaging has become an important diagnostic and follow-up method for AD with its non-invasive and quantitative advantages.

Case presentation: We report a case of a 59-year-old female with a diagnosis of depression at the age of 50 after a 46-year-old onset and a 9-year follow-up observation, who developed cognitive dysfunction manifested by memory loss and disorientation at the age of 53, and eventually developed dementia. Combined with neuropsychological scales (MMSE and MOCA scores decreased year by year and finally reached the dementia criteria) and the application of multimodal imaging. MRI showed that the hippocampus atrophied year by year and the cerebral cortex was extensively atrophied. 18F-FDG PET image showed hypometabolism in right parietal lobes, bilateral frontal lobes, bilateral joint parieto-temporal areas, and bilateral posterior cingulate glucose metabolism. The 18F-AV45 PET image showed the diagnosis of early-onset Alzheimer's disease was confirmed by the presence of Aβ deposits in the cerebral cortex.

Conclusion: Early-onset Alzheimer's disease, which starts with depression, often has atypical symptoms and is prone to misdiagnosis. The combination of neuropsychological scales and neuroimaging examinations are good screening tools that can better assist in the early diagnosis of Alzheimer's disease. Graphical Abstract.

Keywords: Alzheimer’s disease; case report; depression; magnetic resonance imaging; neuroimaging; positron emission tomography.

Graphical Abstract

Figure 1

(A) The score of neuropsychological scale. The patient’s depression and anxiety scores, are decreasing. The scores for cognitive, dysfunction are increasing year by year. (B) The score of each cognitive domain in MOCA. Visuospatial/executive function, delayed memory, attention, and orientation are declined year to year. (C) Time line.

Figure 2

(A) The brain volume changes in regions of interest. The patient’s hippocampal, amygdala, occipital, temporal, and insula brain area volumes have gradually decreased over the last 3 years. (B) MRI results (①–⑨). ① 2014.12 Coronal T2. ② 2017.7 Coronal T2. ③ 2018.3 Coronal T2. ④ 2014.12 Coronal T1. ⑤ 2017.7 Coronal T1. ⑥ 2018.3 Coronal T1. ⑦ 2020.11 Coronal T2. ⑧ 2022.3 Coronal T1. ⑨ 2023.2 Coronal T1. ①–⑥ No significant atrophy in the hippocampal region. ⑦–⑨ The degree of brain atrophy gradually increased.

Figure 3

(A) ① The 3D T1 MRI. ② the image ¹⁸F-FDG PET fused with MRI. ② Showed hypometabolism in the parietal, temporal, and posterior cingulate gyrus. (B) ③ The 3D T1 MRI. ④ The image ¹⁸F-AV45 PET fused with MRI. ④ Showed significant cortical Aβ deposition.