| G30 | Alzheimer's disease |
| G30.0 | Alzheimer's disease with early onset |
| G30.1 | Alzheimer's disease with late onset |
| G30.8 | Other Alzheimer's disease |
| G30.9 | Alzheimer's disease, unspecified |
| G31 | Other degenerative diseases of nervous system, not elsewhere classified |
| G31.0 | Frontotemporal dementia |
| G31.01 | Pick's disease |
| G31.09 | Other frontotemporal dementia |
| G31.1 | Senile degeneration of brain, not elsewhere classified |
| G31.2 | Degeneration of nervous system due to alcohol |
| G31.8 | Other specified degenerative diseases of nervous system |
| G31.81 | Alpers disease |
| G31.82 | Leigh's disease |
| G31.83 | Dementia with Lewy bodies |
| G31.84 | Mild cognitive impairment, so stated |
| G31.85 | Corticobasal degeneration |
| G31.89 | Other specified degenerative diseases of nervous system |
| G31.9 | Degenerative disease of nervous system, unspecified |
| G32 | Other degenerative disorders of nervous system in diseases classified elsewhere |
| G32.0 | Subacute combined degeneration of spinal cord in diseases classified elsewhere |
| G32.8 | Other specified degenerative disorders of nervous system in diseases classified elsewhere |
| G32.81 | Cerebellar ataxia in diseases classified elsewhere |
| G32.89 | Other specified degenerative disorders of nervous system in diseases classified elsewhere |