Cognitive Training and Neuroplasticity in Mild Cognitive Impairment

Inclusion Criteria: 1. Males and females 55 to 95 years of age (inclusive) at the time of informed consent. 2. Subjective cognitive complaints, i.e., memory or other cognitive complaints, e.g., naming/language. 3. Meets criteria for cognitive impairment defined as scores \> 1 below standardized norms on memory function as identified by the Wechsler Memory Scale (WMS) III Logical Memory immediate or delayed recall score. 4. Folstein Mini Mental State score ≥ 23 out of 30. 5. A family member or other individual who is in contact with the patient and consents to serve as informant during the study; this can be a telephone informant in the case of patients who do not have a live-in informant or close significant other. 6. Access to a home desktop or laptop computer at acceptable internet speed for the study duration. Exclusion Criteria: 1. Diagnosis of dementia of any type. 2. Current clinical evidence of schizophrenia, schizoaffective disorder, major depression, psychosis, or bipolar I disorder (DSM-IV criteria). 3. Active suicidal ideation or plan. 4. Current or recent (past 6 months) alcohol or substance use disorder (DSM-5 criteria). 5. Clinical stroke with residual neurological deficits. While we will not exclude patients with cerebrovascular disease, we will not include patients who have had a stroke with residual clinical deficits because it is not clear that this type of patient is similar to the MCI (Mild Cognitive Impairment) patient generally, and clear-cut neurological impairment, e.g., hemiplegia/hemiparesis or speech impairment, may compromise the patient's ability to do the CCT or active control procedures and to complete the neuropsychological test battery. 6. Use of medications known to have a negative impact on cognition: benzodiazepines in lorazepam equivalents greater than or equal to 1 mg daily, narcotics, anticholinergics. Other patients receive medications that may be associated with cognitive impairment but are rarely considered the likely etiology, e.g., theophylline, nifedipine, beta blockers; they will not be excluded. Patients receiving other psychotropic medications not expected to have a material impact on cognition, e.g., SSRIs (Selective Serotonin Re-uptake Inhibitors) and SNRIs (Serotonin-norepinephrine re-uptake inhibitors) will be eligible. 7. Presence of any of the following disorders: a) Central Nervous System infection, with cerebrospinal fluid evidence of meningitis, encephalitis, or other infectious process; b) dementia of any type; c) Huntington's disease; d) Multiple sclerosis; e) Parkinson's disease; f) Other neurologic disorders with focal signs, e.g., amyotrophic lateral sclerosis; g) Mental retardation. 8. Acute, severe unstable medical illness. For cancer, acutely ill patients (including those with metastases) will be excluded, but past history of successfully treated cancer will not result in exclusion. 9. Contraindication to MRI scan: pacemaker, metal implants following surgery, any other contraindication to MRI. Eligibility for the MRI scan is a requirement for the study. 10. UPSIT (University of Pennsylvania Smell Identification Test) exclusions: current smoker \> 1 pack daily, current upper respiratory infection (retested as soon as the infection clears). UPSIT scores are reduced in schizophrenia, Parkinson's disease and Parkinson's related conditions; these disorders are exclusion criteria for this study. Patients with UPSIT exclusions, e.g., current heavy smoker (less than 3% of older adults in our experience), will not receive the UPSIT but will continue to participate in all other aspects of the study. 11. Patients lacking English-speaking ability as determined by self-report and clinical evaluation. 12. Regular online brain training or regular crossword puzzle user, defined as doing these procedures at a frequency of twice weekly or greater during the year prior to screening. Eligible participants who join the trial are instructed not to do these procedures on their own during the trial, i.e., independent of the study. 13. Participation in another intervention trial for cognitive impairment.