Other neurocognitive disorders. Major and mild NCDs due to other neurodegenera- tive processes (e.g., Lewy body disease, frontotemporal lobar degeneration) share the in- features of their own. In major or mild vascular NCD, there is typically history of stroke temporally related to the onset of cognitive impairment, and infarcts or white matter hy- perintensities are judged sufficient to account for the clinical picture. However, particu- larly when there is no clear history of stepwise decline, major or mild vascular NCD can share many clinical features with Alzheimer’s disease.
Other concurrent, active neurological or systemic illness. Other neurological or sys- temic illness should be considered if there is an appropriate temporal relationship and severity to account for the clinical picture. At the mild NCD level, it may be difficult to dis- tinguish an Alzheimer’s disease etiology from that of another medical condition (e.g., thy- roid disorders, vitamin B12 deficiency).
Major depressive disorder. Particularly at the mild NCD level, the differential diagnosis also includes major depression. The presence of depression may be associated with re- duced daily functioning and poor concentration that may resemble an NCD, but improve- ment with treatment of depression may be useful in making the distinction.
Most individuals with Alzheimer’s disease are elderly and have multiple medical conditions that can complicate diagnosis and inﬂuence the clinical course. Major or mild NCD due to
Alzheimer’s disease commonly co-occurs with cerebrovascular disease, which contributes to the clinical picture. When a comorbid condition contributes to the NCD in an individual with Alzheimer’s disease, then NCD due to multiple etiologies should be diagnosed.
A. The criteria are met for major or mild neurocognitive disorder.
B. The disturbance has insidious onset and gradual progression.
C. Either (1) or (2): 1. Behavioral variant: a. Three or more of the following behavioral symptoms: i. Behavioraldisinhibition.
ii. Apathy or inertia.
iii. Loss of sympathy or empathy.
v. Perseverative, stereotyped or compulsive/ritualistic behavior.
v. Hyperorality and dietary changes.
b. Prominent decline in social cognition and/or executive abilities.
2. Language variant: a. Promihent decline in language ability. in the form of speech production, word finding, object naming, grammar, or word comprehension.
D. Relative sparing of learning and memory and perceptual-motor function.
E. The disturbance is not better explained by cerebrovascular disease, another neurode- generative disease, the effects of a substance, or another mental, neurological. or sys- temic disorder.
Probable frontotemporal neurocognitive disorder is diagnosed if either of the following is present; otherwise, possible frontotemporal neurocognitive disorder should be di- agnosed: 1 . Evidence of a causative frontotemporal neurocognitive disorder genetic mutation. from either family history or genetic testing.
2. Evidence of disproportionate frontal and/or temporal lobe involvement from neuroim- aging.
Possible frontotemporal neurocognitive disorder is diagnosed it there is no evidence of a genetic mutation, and neuroimaging has not been performed.